Lynda Ellis, Extension Master Gardener in Anoka County, February 25, 2015
You can’t afford a greenhouse. You don’t have room for an inside seed-starting area. You don’t have much time. But you (and/or your children) would like to grow plants from seed. Help is here.
Do you have a one-gallon plastic jug? Milk, juice and water come in these. If yes, you can do winter sowing. Make a seed-starting greenhouse out of the jug, place it outside in the ice and snow, and, in the spring, get sprouts to plant in your garden.
Decide on your seeds. Seeds for perennials (astilbe, butterfly weed), annuals (cleome, marigold), and vegetables (tomato, lettuces) can all work. Most people use one type of seed per container and make several containers.
Make your greenhouse. Materials needed: clean, one-gallon, food-grade, translucent plastic jug; sharp paring knife or scissors; clear, 2” wide, plastic mailing tape; permanent marker. Take the cap off the jug and turn it upside down. Tape a strip of tape to the bottom, and write the name of the seeds you will be planting using the marker. Turn the jug right side up. Cut a small vertical slit at the bottom, in the middle of each of its four sides. With your marker, draw a horizontal line around the jug below the handle, about 3” from the bottom; start and stop the line at the label. Carefully cut through the jug, following the line. Do not cut through the label; it will be your hinge.
Plant your seeds. Materials needed: seeds; about 5 cups of seed-starting or potting soil; water; same tape as above. Open the jug and fill the bottom part with soil, to within about an inch of the top. Add water to moisten the soil, until it drains through the slits. Do this in the sink or other place where the jug can drain. Plant your seeds, as many as you want. Add a small layer of soil to cover them if needed, and pat it down. Close the jug. Use a small piece of vertical tape to close the side of the jug opposite the label. Wrap a longer strip of tape around the jug to completely seal it. Keep the top open.
Place the jug outside. When? January, February, or March for perennials. Early April for annuals and vegetables. Where? North or east locations are best. It doesn’t matter if the jug gets snowed in. When the snow melts, it will water the seeds. You should see condensation in the jug. If there is no snow on top and no condensation, add water to keep the soil moist. When temperatures start to warm, remove the tape and open the jug. Keep it open during warm days, and close it (use the vertical piece of tape) during cool nights. Seeds will remain dormant until the right time for them to sprout. When the sprouts are big enough to transplant, they will have hardened to the outside air. For further information see: http://www.wintersown.org/.