Take advantage of your greenhouse in April and May, before you plant your tomatoes and cucumbers, to give you an early crop of spinach or Asian greens!
Riley Brennan, of Dawson City, direct seeds spinach in her greenhouse as soon as the soil thaws in April. She leaves the greenhouse unheated and the seedlings don’t require any covering. By the time she goes to plant her greenhouse proper in late May, she has a crop of baby spinach to harvest.
France Benoit of Yellowknife, NWT, direct seeds lettuce and Asian greens in April in her unheated greenhouse. These vegetables require the ‘two cover technique’: once planted, she keeps them covered with row cover. The greenhouse acts as one layer of cover and the row cover acts as the second layer.
Even though it is often -10C to -20C at night, still snow on the ground and the seedlings sometimes freeze in the night under their row cover, as soon as the sun comes out they thaw again and continue growing without a blemish. The water is being taken out of the cell walls when they freeze and then comes back in when the warmth is back. By the time she goes to plant her tomatoes in the end of May, France has lettuce and Asian greens to harvest!
France learned these techniques from Eliot Coleman’s Winter Harvest Handbook.
You can find these and many more tips for growing in unheated greenhouses and cold season harvests in “The Winter Harvest with Eliot Coleman”