Small Acres – Part 4

The "Greenhouse"Basics of Transplant Production – Setting Up Your Greenhouse

The third session of the Putting Small Acres to Work brought us to this talk by Hans Bishop of PrairiErth Farm, in Atlanta, IL.  I was very impressed with how large Hans and his Wife, Katie, grew their small farm business in a relatively short period of time.  They plant between 7 and 9 acres of vegetables that they sell at a farmers market in Springfield.  One of my notes is “specialize in diversity.”  They don’t just grow carrots – they grow orange carrots, yellow carrots, purple carrots.  They grow beets in red, white, and orange.  And more.  Diversity!

The difference between a greenhouse and a high tunnel (see Part 1 of this series) is heat.  A high tunnel (or hoop house) relies on the heat that can be captured from the sun.  A greenhouse has an added heat source.   The greenhouse is used to get plants started.  When the greenhouse gets too full and the plants are larger, they move some into unheated hoop houses until it’s time to transplant them into the field.

So, here are my notes:

Set up.  You need to figure out how many transplants you want to make in a year.  You don’t want to outgrow the greenhouse too fast, or have too few transplants and waste money on heating a greenhouse that is too big.  You need to figure out how many plants will be in there at any one time.  This is where having hoop houses, too, comes in handy.  Different plants need to be started at different times.  You may be able to have a smaller greenhouse for starting some plants, and then move them into a hoop house when it’s time to start something else, but the first plants aren’t able to go outside into the field just yet.  What will your heat source be?  Propane, electric, etc.  And what is the greenhouse going to be covered in?  Plastic sheeting, polycarb, glass, or something else?

What’s important?  Have systems ready to go.  Have backup systems.  Plan, plan, backup, backup.  Keep records from year to year so you can see what works and what doesn’t.

Air circulation is very important to prevent disease and produce stronger plants.  They need some exposure to gentle wind to grow strong.   You can use fans, open doors, roll up the sides if you have plastic sheeting.  Air circulation also makes the temperature inside more constant and prevents hot and cold spots.

Effective use of heated space (to save money).  Use of a germination chamber  is more practical for starting seeds in the early months.  Heat mats with a thermostat are very helpful.  You can also hang a sheet of plastic from the ceiling of the greenhouse to create a germination chamber so you’ll need to heat only that small part of the greenhouse.  A bucket heater can be used to increase humidity and moderate the temperature.

Benches.  They use 2×4’s and sawhorses to set boards on to make benches.  They’ve obtained bread trays to put the soil blocks in and those trays sit on the benches.  He believes that building your own benches is best – cheaper and you make them the size you want them.  Plywood on the top can be used to add a flat work surface where you need it – and is easily moved to another area as you work.

They make their own soil blocks to put the seeds in.  Currently they buy a mixture from someone else, but they started by mixing their own.  It’s basically 3 parts peat, 2 parts compost, 2 parts perlite or vermiculite, 1 cup of sand, blood meal, cottonseed meal, and a dash of lime.  For germination, he uses 50-cell trays and places 7 seeds per cell.  Then I wrote, “heavy duty white plastic.”  I don’t remember why…  Is it for covering the trays to keep moisture in until germination occurs?  For seeds that are difficult to germinate, he sows them in 10×20 flats or broadcast sows them in a tray.  They use bottom heat to speed up germination time.  The plants are separated into one of three different sized soil blocks when the first true leaves appear.  Most go into 1 2/3″ blocks – chard, fennel, lettuce, kale, broccoli, cauliflower, kohlrabi, herbs, cabbage.  These are smaller plants and plants that need a shorter start time.  In 2″ blocks go tomatoes, peppers, eggplant, cucurbits, okra – larger plants, anything that will be in the greenhouse a longer time.  He doesn’t use 3″ blocks much, except for plants that he doesn’t think he’ll be able to plant very soon, and crops with a higher value.

To prepare the plants for the field you need to harden them off by exposing them to some wind, changing temps, and water stress.  Check for diseases.  It’s better to transplant a smaller, more vigorously growing plant than an older, stunted one.

Record keeping is crucial.  Use a field journal and then transfer that information to your computer.  Record your plans, at least what you want and how many you want in the greenhouse.  Record the germination dates, how many germinated of each variety.  That tells you what kinds do best and how many you need to restart to meet your goals.  Create a spreadsheet.  Make sure each tray is labeled clearly.  You’ll never remember all the details.

I appreciated hearing the details of greenhouse growing.  Some of the things he mentioned I wouldn’t have thought of.  He had pictures of his greenhouse, the plants, the soil, and blocking tools – which is good because I had no idea what he meant when he first talked about using a “blocker”.  There’s always new terminology to learn in this farming thing!  I don’t have a greenhouse, so I have no picture of one.  The picture above is our seed-starting table in our dining room last year.  So far this year we have only tiny cauliflower leaves and a lot of dirt.  Not a fun picture.

PrairiErth Farm is another place I’d love to visit one day.  If you live in or around Springfield, you could buy their produce from the farmers market they go to.  Check them out at their website: