Question: We are anxious to plant some vegetable seeds, but our soils are still very wet and cold. Is there anything we can do to help them warm up and dry out?
Answer: Be patient! Tilling wet soil results in compaction and destruction of soil texture. Unfortunately, wet clay soil stays cold late into the spring. Covering the bare ground with clear polyethylene plastic film will help retain the sun's warmth and will often raise the soil temperature 10 to 15 degrees in a few days. A double layer of clear plastic with a small insulating airspace between the layers, will produce even higher soil temperatures.
Black plastic is not as effective as clear plastic in warming the soil and results in higher temperatures only when in contact with the soil.
Wavelength selective plastic film, which allows heat waves to penetrate the film but keeps light rays from entering, will also warm soil effectively in early spring. This type of material (marketed as infrared transmitting (IRT) plastic or under brand initials Al-Or) is used from early spring through the growing season.
Building raised beds 10 to 12 inches above the normal soil level have many advantages for short season vegetable production. Soil in raised beds dries out and warms faster in the spring, and drainage is better throughout the season, allowing for earlier planting and better plant growth. Soil in raised beds with a southern exposure will warm more than level soil. Add new soil, or amend native soil, during the formation of the beds. Make beds three to four feet wide so you can work from the pathways on either side, eliminating compaction from foot traffic.
Question: We added a lot of organic material (compost) to our garden last fall, and we can't believe the difference it has made in our soil. We have actually rototilled it already. Which vegetables can we safely plant now?
Answer: Cool season vegetable seeds can germinate in soil that is 40 F or cooler. They are also able to grow and mature when exposed to cooler day and night temperatures. Most can resist some frost and light freezes. Vegetables that will germinate at 40 F include: Fava beans, beets, broccoli, brussels sprouts, Chinese cabbage, cabbage, carrots, cauliflower, kale, collards, kohlrabi, leeks, parsley, peas, radish, and rutabaga.
Lettuce, onion, parsnip, and spinach will germinate at 35 F Direct planting of these crops is possible in most growing areas.
EDITOR'S NOTE: For answers to local gardening questions, contact Master Gardener Rachel Gana at 642-8723 or e-mail her at: email@example.com.