Greenhouse Manual

Organic Greenhouse Management, 1994 – 2018

Please note that this manual is written in the present tense, but that we no longer grow commercially.


  1. About Room To Grow
  2. Structure / Placement Considerations
  3. Growing Conditions – light, heat, air, water, etc.
  4. Compost, Nutrients and Growing Mixes
  5. Pests and Diseases – prevention and treatment
  6. Seeds – sourcing, germination
  7. Transplanting Options
  8. Organic Standards – Organic Producers Assoc. of MB
  9. Resources

Much of the information in this manual is written with organic and low-input greenhouse growers in mind. The material comes from our efforts to develop a low cost, quality-plant producing process in our greenhouse. Growers interested in appropriate (using-what-we-have) technology should find it useful. Also, the processes and opinions published here represent only the tip of the knowledge heap. Please press me with questions. (Visiting on-site is best. Phoning works at 204.305.0528. Texting that number or emailing at is fine if you want to make a connection.) These pages represent an approach to problem solving that responds to specific situations with specific resources – and so romancing your greenhouse becomes a collaborative process. Enjoy.

1.  About Room To Grow


We grow mostly herb, vegetable and perennial flower varieties for spring bedding plant sales. We’ve developed a unique growing system based on compost and compost tea. Our insect and disease management processes have matured nicely but could benefit from more research/experimentation. I’m quite satisfied with the growing process (propagating mostly by seed and root division) we’ve developed over the years. The learning process has been a bit ponderous and painful at times because we haven’t had mentors nearby to consult with. What we have is a growing method based on local conditions and resources. Because we were certified organic, there are certain requirements we needed to follow that a non-certified organic greenhouse owner could ignore. Certified Organic or not, it seems most important to let customers know what’s being used in the greenhouse.


At Room To Grow we:


  • Specialize in a diversity of medicinal and culinary herb bedding plants. My preference would be to concentrate and expand on the 40 herb varieties we now grow, but growing for a local, rural market necessitates we grow vegetable and flower bedding plants as well. We carry an assortment of open pollinated vegetable, some native perennial flower and a few annual flower varieties. The whole list can be found on our website. Because we have a large garden I have limited experience growing vegetables or herbs to harvest in the greenhouse – although I have done some experimenting with this.


  • Continue to be the only commercial greenhouse in Manitoba that offers certified organic bedding plants – since 1994. We’re certified by Organic Producers Association of Manitoba.


  • Blend our own growing mix using mostly local ingredients. (Commercial soil mixes have wetting agents that are not acceptable for organic growers.) We use compost (made from our horse manure and plant residue), flax shives (a waste material from the flax straw rendering process), MB peat moss and local sand and compost tea.


  • Base the business at home on our Turtle Mountain property so that we can have a fairly sane family life. Our location makes it possible to heat with wood that we harvest from the poplar forest around us.

2.  Structure / Placement Considerations


Because of a. the distance to some of our markets, b. fierce price competition in the bedding plant industry and c. our decision not to operate as a year-round greenhouse, we initially opted to build low cost greenhouses – mostly gothic hoop style structures with double layer plastic coverings. I have also built a 200 square foot lean-to greenhouse onto the south side of our house in which we start our plants every spring. I’ve also built two styles of ‘straw bale’ greenhouse – one of which we will be using for the first time this year. This straw bale greenhouse has bale walls on the east, north and west with a 4 inch sand wall (tin covered and painted black) along the inside north wall for heat retention. 


My primary complaint with hoop style greenhouses is the difficulty in getting natural air flow through them with the consequent need to either use large exhaust fans that pull air across the entire length of the greenhouse or engineer roll up sides – that take away sealing/insulating capacity. In both the lean-to and the straw bale greenhouses I’ve installed inlet vents at the bottom and sides and outlet vents on top allowing for easy, quiet and inexpensive cooling. 


If all that is being grown is spring bedding plants – especially short term vegetable varieties – the need for elaborate heat retention and cooling technology may be minimal. But if the greenhouses are to be used to significantly lengthen the season, or to be used in summer or winter, I feel it’s worth designing extra retention, insulation and cooling features. My inclination is to first consider the lower cost features like hand operated vents rather than gas-cylinder triggered ones, wood heat rather than propane/natural gas, gravel rather than concrete floors and passive solar heat retention rather than active (water or air) systems. These decisions are influenced by the labour available and the income expected.


East-West or North-South Orientation? We’ve done both and prefer East-West due to the potential for insulating the long north and short east and west walls from winter winds. Because most greenhouse plants like to see the sun as soon as they wake up, it’s best to have as unobstructed an east side as possible. Also, most of our strong winds come from the west, southwest and northwest, so protection from those sides (either with coniferous trees or buildings) is preferred.


“Traditionally, commercial greenhouses have tended to favour a north-south orientation to achieve even exposure throughout the greenhouse. Recent research has shown, however, that particularly in more northern latitudes the overall illumination and temperature levels are higher in an east-west oriented greenhouse . . . if one of the primary aims is to maximize solar heat gain then the east-west orientation still remains preferable. It is then possible to have a solid north wall which reduces heat loss considerably while reducing illumination levels only slightly.” P18, The Complete Greenhouse Book, Clegg and Watkins.


Shade can be provided by buying a removable shade cloth cover that blocks as much as 50% of the sun’s light and heat. It’s important not to put this on too early. The plants want all the light they can get so the shade cloth is put on mainly to provide a more tolerable working environment and more pleasant temperatures for customers. When you think long term, it makes sense to plant trees – coniferous at a distance so as not to block light but near enough to provide wind protection and deciduous near enough to provide shade in summer but not close enough so that branches will break and fall on the covering.


Work spaces / Customer spaces. It’s good to think through the view you want your customers to have of your greenhouse – because selling is as much entertainment / aesthetics as it is functional.    Depending on how much customer traffic you expect, you may want to separate the input work area (where soil, water, plants, etc. come into the greenhouse) from the output area (where people take plants away). If the areas overlap, I’ve found that I need to make a physical and mental shift during the first week of May and make the front space welcoming to visitors and customers.

3. Growing Conditions – light, heat, air, etc.


Humidity. Although it’s assumed that greenhouses are by nature humid places, it’s best in organic systems to keep the relative humidity as low as possible – preferably 60% or less. The amount of moisture the air can hold increases rapidly as the temperature in the greenhouse rises. If the greenhouse is very humid when the temperature drops in the later afternoon, all the surfaces in the greenhouse including leaves will become wet from condensation which increases the risk of fungal diseases. Drier plants will also withstand frost better (if the temperature falls to that level for some reason) and will put down more vigorous roots. Most of our homes are around 30% RH and most plants function well with 40% RH as long as they have adequate moisture in the soil. It is best to vent the greenhouse during the heat of the day – allowing the moist air to exhaust – and then close the vents before the outside temperature drops. (Humidity is the water content in the mixture of water vapor with other elements found in the air while relative humidity is the percentage of water vapor in the air at a given temperature.


Carbon Dioxide. If the air is not allowed to freshen (by opening vents) plants will slow their growth as they use up the C02 around them. C02 levels can be improved by workers breathing and moving around the plants (either by their natural movement around the tables or with circulation fans). Also, a raw compost pile in the greenhouse (under the tables but accessible enough to turn) will slowly break down and emit C02. If it is possible to attach an enclosed livestock pen to the side of the greenhouse, the air from that space can be circulated with the greenhouse air to the benefit of both.


Light. When growing most flowers, almost all herbs and all vegetables, the more light the better. Rafters, side and back walls can be painted bright white to reflect more light. It usually is not too difficult to find shaded and partly shaded areas for those flowers that need less light. Against the East, West and North walls and under the variously oriented tables provide possibilities.


Temperature. Each plant variety has its temperature range preference but generally, if you are growing northern climate varieties, plants prefer the day time temperature to be between 20 and 25 degrees Celsius and the night temperatures between 10 and 15 degrees. The range in our greenhouses is wider than this and we still have wonderful plants. If all the other conditions are right (nutrient, C02, humidity, friendly company, etc.) most plants will persevere through a lot. All that is required of us is that we do our best – with what we have. I believe doing our best involves our relationships with the soil and plants. A nurturing, caring attitude does communicate – whether directly or through our management or both. It’s a good idea to learn what we have – where our micro climates are by using thermometers (a high-low thermometer is a good investment) and our own sensitivities. See the Appendix for an example of Greenhouse climate zones.


Water. In our experience, it is more common to over-water than to under-water. When we under-water, the plants will tell us with drooping leaves that they are nearing the end of their ability to cope – but if caught in time, will revive within minutes of being watered.


(This is actually a strategy we use if we feel certain plants are growing too quickly we will deliberately not water them during the regular watering but will keep a watering can near by so we can spot water as they show signs of stress – leaves start to curl and show their undersides. This forces the plant to put more energy into its roots and less into its leaves and branches. This strategy does not work as well for plants that like wet feet all the time – most plants in the mint family for example – and carries with it the down side of potentially drying out the root mass to the extent of making it hard to re-wet. When a pot dries out too much the root mass will pull away from the sides of the pot so that when you water it, the water will mostly flow down the sides and out the bottom. Therefore it’s important to be alert if using this strategy and do the watering as soon as the plant shows signs of stress. If the water does flow right through, you will need to water it repeatedly – every 5 minutes of so for a ½ hour – or set the pot/tray into water for a time to soak.)


When we over-water, it usually takes some time for the plants to tell us something is wrong – by turning yellow with green veins, refusing to grow, looking sickly. Proper watering is one of the more important skills/sensitivities to teach greenhouse workers. I wait for the top soil to be dry, I try to know whether a plant prefers it dry, moist, wet, wild swings between dry and wet or more constant moisture and whether the plant is in a growth spurt or resting time. If I am concerned about a particular plant or group of plants, I will put a brightly coloured stake in the tray to alert me to be particularly attentive as I pass by. I keep in mind what the outside weather is predicted to be for the next day or two, I readily stick my finger down the side of the occasional pot (all while watering) and I will turn off the water long enough to pull a few plants out of their pots to check out the conditions in the root system. That’s a lot to keep in mind if I’m trying to get the watering done as fast as possible. But therein lays the biggest problem – doing the watering too quickly. The watering time is one of the best times to be attentive to what plants are telling us – pure magic when we allow ourselves the time/potential to bless and be blessed.


When we transplant seedlings into their final growing pots we ensure the containers are not quite full of growing mix when we’re finished. Then as we water we ensure each pot is filled to the top without spilling too much to the side. I also prefer to use a meter long metal reaching arm at the end of the hose without a sprayer nozzle. This gives me good reach and gets the water where it is needed and also avoids excess water lying on the leaves – which, I expect, contributes to our lack of disease difficulties. In general, if we decide to water, we water generously so that enough water is offered to wet the pot to the bottom of the roots.


In general, it is best to water in the morning so a. plants have enough water during the heat of the day and b. the humidity caused by the watering can dissipate and the leaves that get wet can dry out. If you try to keep your greenhouse as dry as we do ours, you may need to do a secondary spot watering later in the afternoon if you observe or suspect some plants to be too dry. It’s best to keep watering during cloudy days to a minimum.


We use snow melt water when the seedlings are very young. When this becomes impractical, we use well water. Our well water is high in minerals and comes out quite cold, and so is not best for the plants. In a previous greenhouse, I put well water in a tank and then used a small pressure system to pump this room temperature water to the plants. (This process is also useful if you want the chlorine from a town system to dissipate.) I can’t quantify how helpful this is for the plants. I’m planning a large rainwater collection system to correct our water situation.


Ventilation. The conventional ideal, a greenhouse with adequate and responsive heating and ventilation capacity to keep the temperature and humidity, etc. at the optimum for plant growth, is costly to implement and may not be the best for overall health. My experience is that, what we’re taught to be the ideal for the greenhouse stage of the plant’s growth, may not be the ideal when looked at over the total life of the plant. I find that plants that have been grown in ‘ideal’ conditions are not well suited for conditions in the real world. Our plants get quite a range of experiences in our greenhouse and our customers tell us they don’t even need to harden them off, that they thrive from the moment they are planted. And so I get to thinking that the ‘ideal’ conditions are set to serve the interests of the large conventional growers (providing the lushest looking plants – ie. tops not roots – in the shortest time possible) and not the interests of the plants or the gardener. But back to the issue at hand . . .


A generous ventilation system is certainly needed for a healthy greenhouse environment. It is generally accepted that for ‘fanless’ structures the total vent openings should equal about 1/5 th of the total floor area of the greenhouse. Our 900 ft2 greenhouse has 70 ft2 of venting on the lower south side and 90 ft2 on the upper north side. This is a bit undersized but I can open three large doors – one on each of the east, west and north sides – if I need more air. It is also commonly thought that 40 to 45 % of the vent opening should be low and 55 to 60% should be high – so that air is more naturally drawn up and out even if the wind is not exactly favorable.


If you have a hoop greenhouse without roll up sides, you will need to install an exhaust fan that will draw cooler air from one end of the greenhouse and out the other. The inlet and outlet are best equipped with louvers so that the openings automatically close when the fan is not working. The fan should be able to replace all the air in the greenhouse every few minutes. (Fans are rated for their cubic feet (or meter) per minute capacity) We found that having large door openings on each end of our hoop greenhouses helped us to minimize the use of exhaust fans. But then when the fan started up we would close the fan-end door to ensure the air was sucked right across the greenhouse instead of through the nearest opening. Usually the fan is placed on the east or north ends of the greenhouse so that it doesn’t suck against the prevailing winds.


The decision needs to be made whether to screen these openings or not. If you plan on using imported beneficial insects, you’ll want to ensure they don’t all get sucked out by the wind or the fan.

 4. Compost and Growing Mixes


All winter we feed hay to our horses and donkey. In spring I push the manure and trampled left-over hay, along with any kitchen and garden scraps we’ve dumped there, into a pile with our tractor. The fresh pile is two to three meters wide, about two meters high and ten meters long. A compost thermometer helps me read the temperature in the middle of the pile. When it reaches 60 degrees C / 140 degrees F in at least two places I turn the pile with the tractor loader. The pile needs to reach at least 55 degrees C / 120 degrees F to kill most of the weed seeds but if it goes over 65 degrees F it begins to burn away nutrients. When this happens the hot spots turn gray – a sure sign we’re losing the vitality of the compost. When the thermometer isn’t handy, I wiggle my arm into the pile (less messy when dealing with a more advanced pile) and if it feels uncomfortably hot I know it’s time to turn it. (A bath that is hard to get into is usually about 50 degrees C)


I land up turning the pile 6 to 8 times (at first every few days and then it tapers off to be every week or two) until it cools off and has become a fibrous black pile of goodness. Because I pile up the compost just after the snow melts and because the pile sits in a sheltered location, I find I don’t need to add any water to the pile. I sieve the compost in fall or early spring through a half inch mesh and put full containers in the greenhouse. The only down side I see to using compost as our growing base is the occasional weed population we get in the greenhouse when we don’t manage to kill the weeds that go to seed around the compost pile. Most years we have next to no seeds in the compost.


We’ve made plant residue compost and we’ve used pig, chicken and goat manure and various combinations of the above in our compost heaps. For the greenhouse, I find horse manure compost to be perfect because it’s so fibrous, so available and has the balance of nutrients we need. We mix the compost with local sand (we sieve through a 1/4 inch sieve), Manitoba peat moss and sieved flax shives (a by-product of the flax rendering process). We do the mixing by hand in a sieving/mixing box made for the greenhouse.


Our standard growing mix is:

2 parts composted horse manure – ½ inch sieve (Ensure it’s certifiable organic, check with OPAM)
1 part well aged flax shives – ½ inch sieve (Aged in the weather for two years or more)
1 part peat moss – ½ inch sieve (Make sure there is nothing added to the pure peat moss)
½ part sand – ¼ inch sieve (Make sure the supplier has not sprayed the sand pile)

Notes. Flax shives are increasingly hard to get, so I use 2 parts peat moss instead. Also, I’ve found that if sand has a bit of dry (so it sieves well) clay in it, the plants are happier. There are mineral nutrients in clay and the mix will hold moisture longer. This is something you can experiment with, as some plants need more drainage than others.


I sieve these ingredients in layers so that the lightest materials (peat and shives) are on the bottom, then the compost and then the sand on top. Having the heavy items on the top makes the mixing (by flat spade or shovel) easier. If the finished mix is too dry for transplanting, I will either add enough water or compost tea (depending on what the plant needs are) and mix it so that a handful is damp but I can’t quite squeeze a drop from it. During a day of steady transplanting, it feels good to occasionally move vigorously at the end of a spade. Sieving and mixing one batch (about 5 x 16 lt pails in volume) takes me 10 to 15 minutes. If the compost is very wet, it could take longer to do the sieving.


The standard mix needs to be adjusted if similar ingredients aren’t available or if the particular plants require a richer or lighter growing medium. Some examples are:

  • If chicken source compost is used, less is needed because it is so rich in nitrogen. Pig and cattle source compost is less rich than chicken compost but richer than horse compost.
  • According to organic standards, perlite and vermiculite can be used instead of sand. (These are mined and transported from the Rocky Mnts. And so are less sustainable for the long term.)
  • Some herbs – Echinacea for example – need a sandy, low nutrient growing medium and so I double the sand and ½ the compost.
  • Tomatoes are fine in 100% horse compost – as long as drainage is maintained by not consistently over watering.


Scientist tell us when soil temperatures fall below 12 degrees Celsius, organic fertilizers either break down very slowly or not at all as the soil organisms relied on to break down and make available nutrients are not active below this temperature. Compost tea can be used sparingly to help out with added nutrients during a cold spell but care must be taken not to saturate the soil and cause an over-watering problem.


Compost Tea. When we transplant into the growing mix (beginning at the end of March) we soak the transplants in a compost tea solution. We make tea by putting about 12 liters (3 gallons) of horse compost into a grain sack and hanging the sack in a 75 liter barrel or plastic garbage container. We leave it to steep for 24 hours or so (pulling the sack out of the water occasionally and jostling it a bit helps) and then lift the sack out and let it drain over the container for a couple hours before using the tea. I have two batches going so I can use one while steeping in the other. It’s best to use it within a day or two – or keep it cool and in a shady area.


I usually use the tea straight if I need to treat damping off in the germination chamber, or one to one with water in the soaking tray or two parts water to one part tea when fertilizing the plants with a watering can later in the growing process. I can’t provide any scientific data to prove the value of the tea – although the Soil Soup website has some of this. What I have learned, though, is that I no longer need to use any imported nutrient in the growing process. I used to bring in fish emulsion and kelp products. Compost and compost tea do it all now. The plants hold their colour and vigour to the end of June. Some growers and researchers say that compost tea is more effective if stirred / aerated before being used. We don’t do this consistently and find the tea works well. If you are using cattle, pig or chicken compost tea, the ratios need to be adjusted.


I’ve twice submitted our growing mix for scientific analysis. This is only good to do if you know how to use the numbers given. Once I called the tester and was told the nutrient balance was better than he had ever seen in a home made mix. This did more for my confidence than the statistics. We see that it works well, and so we no longer test it.

5. Pests and Diseases


Over the last 11 years we’ve had very little insect stress in the greenhouses. We expect this is so because we grow a wide diversity of plants in our greenhouses and so any insects that take a liking to any specific plant have to contend with a bunch of plants they don’t like as well. Most years we use no insecticide (only a bit of insecticidal soap if tested by aphids) and so we rarely harm the beneficial insect population in the greenhouse. In warm weather we leave the doors wide open for any insect that wishes to visit and have had few destructive callers. We don’t push nitrogen in our growing mix, which encourages slower growth and allows the plants more resources to combat insect and disease challenges. New studies are showing that plants need to be tested by insects in order to develop the antioxidants we need to fight off the diseases we are challenged with. When we use pesticides on our crops we may get more productive crops but we may also suffer more disease because of it. So we consider the insects’ world to be a friendly place – most of the time.


The best approach is to predict and prevent problems. Some of the following suggestions come from our experiences and some from the experiences of other greenhouse growers we’ve spoken with. We’ve also used some suggestions from ‘Horticultural Management of Solar Greenhouses in the Northeast’ by Miriam Klein.



1. Natural Growth rather than Forcing. Most greenhouses manipulate the growth rates of plants by providing nutrients (like nitrogen for vegetative growth and potassium for flower development) that force advanced maturity or by stunting with chemicals that slow or ‘freeze’ the growth. Although these manipulations can create greenhouses that look lush and beautiful, the plants are not necessarily healthy and can be more vulnerable to diseases and pests and therefore may need more chemical treatment. Conventional greenhouses are some of the most toxic environments on earth when the amount of synthetic agricultural chemical used per square meter of space is measured. Organic greenhouses require a more thoughtful approach that is in tune with each plant’s natural needs. The growing mix should be rich enough to encourage plant growth but not so rich as to force the plant. See ‘Growing Mixes’ for more on this.

2. Diversity of Plants. The greater the diversity of plant varieties in the greenhouse, the less likely a disease or pest can take hold. If faced with an entire greenhouse with one variety of plant, the grower can expect a simple problem to expand into a major problem quickly. Therefore organic growers are more likely to arrange for diversity.

3. Cleanliness. Forests and gardens take care of dead material by returning it to the soil quickly. Greenhouses are separate from many of the natural processes that have active life cycles in place and so are more prone to molds and mildews. Prevention involves putting all cuttings and culls in a compost heap immediately.

4. Humidity. To help avoid disease problems, keep the greenhouse as dry as possible by watering only as much as is needed to maintain steady plant growth and by avoiding water spills or open sitting water. Disease is more readily transferred when the leaves are wet.

5. Hose Care. Keep the nozzle of your hose off of the ground. It’s possible to pick up soil diseases and spread them with the hose.

6. Clean Recycled Pots. Consider disinfecting used pots that come in from outside the greenhouse with a solution of 1% Hydrogen Peroxide. H202 is available in bulk as a 35% solution compared to the more expensive 3% solution found in drug stores. I get mine from a nutritionist/veterinarian friend.

7. Remove old and/or diseased plants. The three rules of prevention are observation, observation and observation. If you see a problem when it is only affecting one or two plants, you can deal with it in a matter of minutes and move on. If it is affecting 100 plants, you will spend all day taking care of the problem. Remove or isolate the affected plant(s) and consider what else is needed to prevent the problem from reoccurring. Over time we learn which symptoms require forthright action and which require patience. (See the Appendix for specific afflictions.) I use the watering time to take a quick overview of the health of the plants making mental notes of which areas I need to return to for closer scrutiny. I also take leisurely walks through the greenhouse – particularly in the morning before I get caught up in the tyranny of the to-do list to observe and to be observed – for often the problems that need to be prevented and attended to are within me.

8. Check any plants brought into the greenhouse. It’s a good idea to have a transition space in which to keep all imports for a few days until you are fairly certain there are no stow-away pests and diseases.

9. Wash hands and tools used in dealing with diseased plants.

10. Don’t smoke tobacco in the greenhouse. Also wash your hands if you’ve handled rolling tobacco. The tobacco mosaic virus is a nasty visitor – especially for tomatoes and peppers.

11. Rotate the crops – if you are using growing bins or the ground soil.

12. Keep records of pest and disease stresses. Note the problem, the plant variety and stage of growth, date and what was done to address it. Over the years you may see patterns (you don’t see when in the thick of the growing season) that can trigger lasting changes in your management approach. For example, I learned that I get aphid problems when the grass turns green in spring. So I now ensure the grass around the greenhouse is cut short in fall and I become increasingly attentive when fresh grass greets me in spring. I installed screening on all lower vents and this helped immensely. 

13. Get to know your own greenhouse. This takes time. So be patient and deal with stresses calmly when they arise.


The Pest and Disease Control pages in the Appendix come from Horticultural Management of Solar Greenhouses in the Northeast by Miriam Klein. Although this is not a book written specifically for organic greenhouse growers, it is consistent with organic principles.

6.  Seeds – Germination


Generally, vegetable plants that grow readily on the prairies have seeds that germinate easily in a moist medium at about 20 degrees Celsius with a moderate covering of peat moss within a few days to a week. Please see the Resources section for books and websites with more detail on specific varieties. Herbs tend to be a bit fussier and flowers are all over the map. We use three processes for germinating – each requiring its own soil mix. Most small seeds require a moist, friendly place to sprout and require no nutrient until they get to the first true leaf stage.


a. Standard Germination. The vast majority of our seeds are sown in a medium made of 6 parts peat moss (1/4 inch sieve) mixed with 1 part sand (also ¼ inch sieve). This mix is moistened with snow melt water or rain water to the point where I can squeeze out a drop or two when I make a fist. I place the mixture in germination pots or trays (depending on how much I need to plant) filled to the top without packing it at first (it’s important to keep the mix airy so that the new roots can easily penetrate down into the pot/tray) I lightly settle the mix down with a clean block of wood (mine is cut to exactly fit into the top of the containers I most often use) so as to make a level surface on which to sprinkle the seed and so that there will be room to water the surface later. The seed is sprinkled on the surface (making sure I don’t plant too thickly because the damping off virus enjoys close quarters). I use my block of wood to press the seeds gently into the surface of the peat moss and make sure to wipe off any seeds that stick to the wood. If the seeds need to be covered, I make note of the depth the seed prefers and sprinkle dry sieved peat moss on top of the seeds. I then pat this down gently with the block of wood and then generously spritz the container with rain/melt water making sure I don’t spritz so aggressively that the covering or the seed is disturbed. If the seed does not require covering, I simply press them gently into the peat moss and spritz. (I use 1200 and 600 series containers for most of my plantings – which is industry lingo for containers that will either fit 12 or 6 per standard tray. If you need less than a case of these you can buy them at Lindenbergs (Brandon) or at large garden centres in Winnipeg.)


I place the containers in a germination shelf where I can keep the temperature constant and easily check and spritz as needed. I do this in a temporary chamber in our home because human room temperature is perfect for most seeds. If I am concerned about the containers drying out with too much air movement, I will place a sheet of plastic over them. I spritz only those containers in which the top surface is drying out. I do a good spritzing in the morning (as needed) and then check a few times during the day, trying to avoid spritzing late in the day. Try to ensure by judging weight that the containers remain moist to the bottom so that the sprouting seeds will readily send roots down rather than hang around the surface. This is not a problem if you remain attentive to spritzing just as the containers begin to dry out. It’s also important not to spritz too much, so look for the signs rather than doing it by routine.


If you cannot do the germination in your home, you may need to fashion a simple germination chamber that basically gives the seeded containers a place where the temperature can be controlled and a place out of cold gusts of wind. We’ve used car warmers, space heaters, hot water and furnace pipes to supply the gentle regulated heat. Be creative with what you have. Although you don’t want too much air movement, you do want a gentle movement of air to avoid the damping off virus taking a liking to your chamber. This can be achieved by making openings around and on top of the chamber that you can cover if need be.


As soon as the seeds begin to pop, move the container into the light – either sunlight (in a warmish, sheltered place in the greenhouse) or artificial lights. I find window sills are only good for a few days. The sprouts are looking for light that is directly above them and will stretch their bodies toward the window in the hope of finding a vertical path to the light – making for weak seedlings. When using grow lights (any florescent bulb will do) try to position the light as close as possible just above the plants so they don’t feel they need to stretch. Make sure you have enough bulbs to provide adequate light for the containers you expect to have in the sprouting to transplant stage.


Until the seedlings get to the true leaf stage they do not need nutrients. They feed off of the food their parent plant put into the seed. I will sometimes water a container with compost tea if either a. I can’t get around to transplanting the sprouts as soon as I feel they should be or b. if I see signs of damping off.


Damping Off. If sprouts begin to turn a dark green colour and fall over as if slashed at soil level and this condition progresses like a slow moving wave to other sprouts, I immediately scrape away the affected soil and a bit more along the edge of the ‘wave’. I struggled for years to find a way to strengthen the sprouts and treat the damping off – on the odd occasion that it would appear. I tried chamomile tea and misting with 1 % H202 – both of which had some effect. But a friend who works at a golf course told me he uses fine compost to prevent and treat snow mold on the greens. This alerted me to the possibility that compost tea may be good for other molds and fungi. Again, I’m not aware of any science behind this but it works well for me when I lightly water the affected container with full strength compost tea. The best approach is prevention though – enough air, not too humid or wet and space between the sprouts.


b. Bunch Plantings or Transplant-Phobic Varieties. Some sprouts don’t like to be transplanted or are best planted in bunches that make them difficult to transplant – and so these are planted directly into plug trays – or sometimes as in the case of very large seeds – directly into 3 ½ “ pots. This requires that the seeds germinate into a medium that has nutrient already in it – usually the standard growing mix. I fill the plug tray or 3 1/2” pots with moist standard growing mix, make a depression in the middle and sprinkle the seeds into the depression and then cover with extra growing mix and gently pat it down to ensure good contact between the seed and the medium. With large seeds I simply push the seeds down into the growing mix and pat it down a bit. I then wet the containers well and put them in the germination chamber or in a consistently warm place in the greenhouse.


c. Echinacea. Either through force of habit or because I was so pleased to find a method that would trick the Echinacea seed into thinking it was spring, I haven’t experimented with less complex processes. I place a couple of layers of paper towel into a solid tray or sealable plastic container and spritz the towel so that it is wet but not dripping. I cut a few smallish chunks of apple (which provide a gas that aids the process) onto the towel and then sprinkle the seed on the rest of the towel surface. You can spread the seed fairly thick if you need to as long as they don’t overlap. I spritz the seed to ensure everything is good and moist. Cover the container with clear plastic and place in a cool place like a fridge or cold storage in which the temperature is between 2 and 8 degrees Celsius. Make sure there is a light on 24 hours a day above or near to the container and leave it alone for 3 or 4 days. Then place the container in a warm place (room temp.) with a light on 24 hours per day, up close to the container, and make sure the seeds and towels are still moist and covered with clear plastic. In 4 to 10 days the seeds will pop fuzzy root tails and then send out green sprouts. When the green sprouts are 1 cm. you can transplant them into plug trays and use natural light.


Stratification and Scarification. The process explained above for Echinacea is an elaborate form of Stratification – forcing seeds through experiences that convince them spring is here. Many perennial flowers and some herbs will germinate much better if mixed with a small amount of moist peat moss or sand and placed in the fridge for a week or a couple months depending on their preferences. When the seeds are taken out of the fridge and planted into containers, they respond like other seeds. Scarification is the process of tricking seeds into thinking they have gone through the digestive tract of a bird or animal. What the digestive process does is break open the hard seed pod allowing the seed to germinate. I take two pieces of medium to rough sand paper and roll the seeds around vigorously between the sheets for a minute or two (holding it all over a large bowl so I don’t lose the seed) depending on how hard the seed hull is. The seeds can then be planted as in a. above.

7.  Transplanting


Some plants get transplanted once, some twice and a few three times depending on their preferences and the size of plant I want to grow. If I want to grow large tomato plants for example I transplant the seedling sprouts into plug trays (one plant per cell) that are filled with standard growing mix. They will grow until they start crowding each other at which time I transplant them again into 3 ½” pots almost filled with sieved compost or a rich growing mix. They grow in these pots until they again get crowded and then I transplant into their final large pots. Other plants grow best if the seed is planted directly into the final pot.


For organic systems the important thing is that compost tea is ready for use when the transplanting is done. The standard procedure is: loosely fill the plug tray or pots with growing mix, making sure the mix isn’t compacted. Loosen a bunch of seedlings by prying up with a pencil (or equivalent tool) from the bottom of the container. Pick up a seedling with thumb and index finger, make a hole in the growing mix with the pencil – large enough so the seedling just fits – and settle the seedling down into the hole so that the root is facing down and the green part of the plant is upright. Settle the soil down gently around the root ensuring there is about 1 cm of space between the soil and the top of the container. Fill the tray in this way and then place it into a bath of compost tea cut with an equal part water (half strength). The containers will soak up the tea/water through the drain holes and provide a nutrient charge to get the transplant going. Once the top of the growing mix in the containers looks wet, the tray can be lifted and allowed to drain for a minute or so and then placed in its growing-on location.


I make a soaking ‘basin’ in which I can soak 4 standard trays at one time. I lay out the 4 trays and screw together pieces of 1 x 4 on end into a rectangle around these trays. (Or you can use a measuring tape I guess) I then drape two layers of good plastic over this rectangle tucking the plastic down into all four corners before stapling the plastic to the top edge of the rectangle. I try to keep this basin more than ½ full at all times as the deeper the tea/water the faster it will be soaked up. When we had a greenhouse with a hot water heater and we were in a hurry we would use warm water in the mix as it is soaked up faster. Some plants are very tender when transplanted and others are robust from the start. Soaking from below ensures that water is not poured over the most delicate seedlings so they don’t have to weather another stress so early on. When transplanting established plants to larger containers it isn’t as feasible to soak the containers so compost tea is used to water the plants from above.

8.  Certification


The question needs to be asked whether the expected certified organic sales are worth entering into a fairly rigorous inspection/certification process. We applied for certification in order to become part of a community of growers – for the personal and business support, the information and the larger educational effort to change agriculture processes across the board to become sustainable. The first few years our certification did not bring us new customers because we were selling everything we grew in our small rural town where we were the only greenhouse. Well, yes, there were two or three customers who drove from some distance because we were certified, but this wasn’t a large part of our business. At one point we began marketing medicinal herbs to farmers, researchers and homemakers at some distance from us. Our certification then became valuable. Certification is foremost for those who are marketing organic food, plants and seeds to people who are not intimately familiar with the person doing the growing – where there is a potential trust gap. Assuming a non-certified organic grower can get the information he/she needs on an equal footing with the certified grower, there is no reason why one should be better than the other. In certain markets, the certified organic grower can ask for and get a premium price that the non-certified organic grower would have difficulty getting. Each grower has to weigh these options on their own.


The other aspect of becoming certified is that there is a fair amount of paperwork to do in early spring – just when life for a greenhouse grower is already busy. The paperwork is most onerous the first year. It can be eased by keeping a well ordered paper trail of all inputs throughout the year – and by copying and filing your application so you can simply repeat yourself from year to year – while noting changes you make to your management process.


We can only legally use the word ‘organic’ to describe our plants or our farm practices if we choose to get certified. 


The National Draft Standard of Canada for Organic Agriculture can be found online – along with lots of great info and links on the Canadian Organic Growers website. I assume you will get the standard with a Permitted and Not Permitted Material List once you contact a certifier with a request for certification. 


Because there are too many products out there that you feel may be of use to you in your greenhouse, I can’t begin to list and comment on them all. Fish fertilizer, for example, might easily be thought of as inherently organic. But the regulation has changed so we can’t use it unless it comes from a certified organic source. It wasn’t available in Canada a few years ago. This change compelled me to experiment with compost tea – so good can come from tighter (even seemingly irrational) regulations.



Parting Notes:


I would like to develop a growing medium that totally eliminates peat moss. Peat bogs take 1000 years or more to grow. Greenhouse, nursery and landscape businesses are dependent on these bogs in a big way. We are destroying so much life every year when we support that dependency. We have managed to phase out half of the peat moss we used a few years ago by blending in flax shives. The reason we can’t eliminate the peat at this time is because the shives take up more nitrogen from the mix than the peat does. We find the shives need to age in the rain and sun for a year or two before we can use them effectively in the greenhouse. Once the shives have broken down they absorb water better and use up less nitrogen in the growing pots.


Finally we would like to cut down on and eliminate the plastic we use in our production and even in the construction of the greenhouse. Once we are serving a more local market, we may be able to make this move. At present we need the plastic pots and trays to transport the plants. We also need a bit more income to be able to afford a glass covered greenhouse.

9.  Resources


Structures and Equipment – If you are certified organic you will need to ensure equipment and inputs are acceptable. Check with myself or OPAM – contact info below.

  • Wholesale Horticultural Supplies – HJS, 330 Transport Rd, (NE corner) Wpg. R2C 2Z2
    Phone: 668-8360, Fax: 667-1775, Email:
    For Greenhouse frames, plastic, pots, trays. Doug or Caleb. Catalogue Available
  • Woven Greenhouse Plastic – Northern Greenhouse Sales – Box 1450, Altona, R0G 0B0
    Phone: 327-5540, Fax: 327-5527, Email:
    Website: Ask for Bob or Margaret Davis
    Catalogue Available
  • Wholesale Greenhouse Supplies – Greenleaf Products – 200 Devos. Ft. Gary, Wpg.
    Phone: 275-5747, Catalogue ?
  • Wholesale Greenhouse Supplies – Cary’s Ltd. – 1555 Inkster, Wpg.
    Phone: 632-4481
    Similar stock as HJS, Catalogue ?
  • Custom Plastic Tags – C. Frensch Ltd. – 4774 Hinan Dr., Beamsville, ON, L0R 1B1
    Phone: (905) 563-4774, Fax: (905) 563-5053, Email:
    You email them a data base of what you want on the tags. Catalogue Available
  • Pre-printed Plastic Tags – JVK – Box 910, St Catherines, ON. L2R 6Z4
    Phone: (905) 641-5599 or (800) 665-1642, Fax: 684-6260, Email:
    Website: Ask for local rep. and catalogue.
  • Organic Inputs – Peaceful Valley Farm Supply – Box 2209, Grass Valley, Calif. 95945
    Phone: (530) 272-4769, Fax: 272-4794, Website:


Seeds and Plants – If you are certified, you need to try to source your seeds from a certified seed distributor. If you cannot find the varieties you need or the amounts you need at a reasonable price, you can ask your certifying agency in writing for permission to use non-certified seed. In the letter give at least three examples of companies (that carry the varieties you need) you have approached. This can be sent in along with your annual inspection application.


If you want to buy plugs (plants that have been started) for your certified greenhouse, you cannot buy non-certified organic annual plugs, raise them in organic soil and then sell them as certified organic. In fact, you risk losing your certification unless you keep these imported plants in a totally separate facility. If you buy non-certified perennial plugs and keep them in separate organic facilities for one year, you can then sell them or use them for cuttings as organic. I’ve stopped importing anything due to these new regulations. This is forcing me to raise my own mother plants (non-hardy types like rosemary and some mints) which is hard to do without a year-round greenhouse. So mostly I do without or try to protect as much of the marginally hardy plants through the winter in our garden as possible so I can take root divisions in spring.


OPAM also expects you to get assurance (either in a letter or from catalogue quotes) that the seeds you have ordered/bought are GMO free.



T + T Seeds Free Catalogue 895-9962 Headingly South
Lindenberg Seeds Free Catalogue 727-0575 Brandon
Sage Garden Herbs $3.00 Catalogue 257-2715 Winnipeg South
Prairie Habitats $2.00 Catalogue 467-9371 Argyle
Prairie Originals Free Catalogue 1-866 296-0928 East Selkirk
McKenzie Seeds Free Catalogue 1-800 205-7111 Brandon

Also, there are many wholesale outlets for plugs in Wpg, Bdn, Portage la Prairie



Prairie Garden Seeds $2.00 Catalogue (306) 386-2737 Chochin, SK



William Dam Seeds Free Catalogue (905) 628-6641 Dundas, ON
Richters Herbs ditto (905) 640-6677 Goodwood, ON
Terra Edibles ditto (613) 961-0654 Foxboro, ON
Agrestal Org. Heritage ditto fax: (905) 888-0094 Gormley, ON



Horizon Herbs – Medicinal $2.00 (541) 846-6704 Williams, Oregon
Johnny’s Seeds –  Free

These are the companies we’ve used or have ordered catalogues from. I buy primarily from Prairie Grown, William Dam, T+T, and Terra Edibles.


Growing Information

Perennials for the Prairies – U of Alberta and Saskatchewan
Annuals for the Prairies – ditto
Wild Flowers and Grasses of the Northern Plains and Black Hills
Herbs and Edible Flowers – Lois Hole
Northern Flower Gardening – Lois Hole
Perennial Favorites – Lois Hole
Tomato Favorites – Lois Hole
Ball Culture Guide – The Encyclopedia of Seed Germination – Ball Seed Co.
Prairie Propagation Handbook – See Prairie Habitat Seeds phone number above.

Compost Tea sites:


Pests and Diseases

Insect Pests of the Prairies – U of Alberta


Organic Standards

Organic Producers Assoc. of MB – Phone: 748-1315, Fax: 748-6881, Email:, Website: – Certification/Marketing/Information

Canadian Organic Growers – (local chapter is Organic Food Council of MB- OFCM)
OFCM: Amy Hawkins-Bowman, Phone: 878-2839, Email:
COG: Laura Telford, Phone: (888) 375-7383, Email:, Web:
– Information, Mail-out Library, Networking, Lobbying, Research
– Draft Canadian Standard:

OCPP/Procert Canada – Phone: (306) 382-1299, Email:
Website: Certification Services based in Saskatchewan and Ontario.

Organic Agriculture Centre of Canada (OACC)
– Prairie Coordinator: Brenda Frick – Ph: (306) 966-4975, Email:
– National Centre – Truro, NS.: Ph: (902) 893-6679, Website:

Organic Materials Review Institute – Info on Permitted Materials for certified systems:



I suggest you pick up a copy of Down To Earth – Guide to Organics in Manitoba, look through the Index of Sources and start by making phone calls or knocking on doors. Who you call on depends on what you are growing. We’ve sold bedding plants through, T+T Greenhouse, Humboldt’s Legacy, Organza, Harry’s Foods, F.O.O.D., and Red River Ex. Park. We could not supply T+T consistently from our location. Other locations decided bedding plants – with their light needs – didn’t suit their situations. We’ve settled into selling through Humboldt’s and direct deliveries to homes in central Wpg. So it’s an experimental process that depends on your production/delivery system and the host’s abilities. Please make your own plan and feel free to call me to discuss your approach. We also sell at block parties and folk festivals. Take a look at everything that is happening within your community (self defined) during the time you have plants to sell and figure out ways of making partnerships with those who want to help you because your success benefits their event/location as well. Or go it alone. Marketing is as much about personality (yours or your organization’s) as it is about product.



Horticultural Management of Solar Greenhouses in the Northeast by Miriam Klein – info on smaller scale greenhouses.

Bubble Greenhouse Design – Ross and Kat Elliott –

The Complete Greenhouse Book – Clegg and Watkins – Garden Way Publications

Manitoba Hydro c/o Ray Boris, Phone: 474-3582, is involved in research on Greenhouse Designs for Manitoba. They have helped fund a year-round greenhouse in Elie – Wenkai Oriental Vegetables. They publish Profiles in R&D. Nov ’02 and Jan ’05 feature designs.


The Romancing Part (I’ve leant these out and don’t have the author, etc. handy)

Secret Life of Plants
Secrets of the Soil
The Findhorn Garden

10.  Appendix


Solar Greenhouse from China, Manitoba Hydro Profiles in R&D Jan. 05, 3 pages
Bubble Greenhouse Technology, Canadian Organic Grower Winter 05, 4 pages
Climate Areas, Horticultural Management of Solar Greenhouses, 1 page
Specific Germination and Growing Needs – Vegetables, 1 page
Pests and Diseases, Horticultural Management of Solar Greenhouses, 20 pages
Misc. Pricing and Marketing, 4 pages
Request for Permission to use Non-Certified seeds, 1 page