In the 1975 Farmstead Magazine “Commonsense Planting Calendar,” the first “Planting Tip” on dealing with Maine’s short growing season was to “sprout early.” By that is meant starting vegetable seedlings weeks or months before it is time to set them out in the garden. Here at Wildfire Fellowship Farm we have constructed a “Propagation House” for that purpose and it is the center of farm activity at this time of year.
Our propagation house is the front third of a well insulated barn. Triple wall polycarbonate glazing allows ample light and solar heat gain while retaining warmth at night. We use a pellet stove for nighttime heat and automatic ventilation fans for daytime cooling. During the very cold, but sunny days of late, temperatures in the propagation house reach 90o by mid-day unless the house is vented. On cold nights we burn 40-80# of wood pellets to keep temperatures above the 65o threshold for tender plants like peppers and eggplants.
High quality seedlings begin with quality seeds. We buy from three suppliers: Johnny’s Selected Seeds (www.johnnyseeds.com), Fedco Seeds (www.fedcoseeds.com), and Highmowing Organic Seeds (www.highmowingseeds.com). The second key to success is the potting soil. We have been very impressed with Lite Mix produced by Living Acres in New Sharon, Maine (www.livingacres.com). Lite Mix is available at retail from Johnny’s as their “512 Mix.” We began using this potting mix because it was recommended for making “soil blocks” and experience has shown that it grows strong, healthy seedlings that hold well if transplanting must be delayed.
Most of our seeds are sown into soil blocks, made by forming a very moist potting mix using “block makers” that compress the mix into two inch cubes. Fifty of these fit just right into a standard greenhouse tray facilitating production count. The benches in our propagation house were sized to accommodate the trays with no waste of space. We have enough bench space to hold 6,000 soil blocks. We also seed directly into loose Lite Mix in deep flats (onions and leeks) and use three inch square pots for direct seeding of cucurbits (squash, cucumbers, melons) and “potting up” of peppers, eggplant, and tomatoes. Electric heat mats under the flats and trays are used to speed germination for the heat loving plants like peppers and squash.
Our first year of using the propagation house in 2013 taught us that conditions are so ideal that the seedlings grow very fast, so this year we have delayed the planting schedule. It is very important that seedlings not be so mature at transplanting that they will be set back. The trick is steady, active growth from seed to garden soil. We use an Excel spreadsheet to schedule and track greenhouse and garden activity and keep things flowing smoothly. For me, working with seeds and potting mix in a toasty greenhouse while the wind howls and the snow is still deep on the hillside is one of my favorite seasonal activities.