I’m planting my fall garden, but it’s so hot outside! What can I do to help seeds germinate when I plant them in hot summer soil?
Most annual vegetable seeds germinate readily in soil temperatures ranging from 70 to 90 degrees Fahrenheit. But in midsummer, soil temperatures can be at the high end of that range — or above it — making it tough to get good germination for some crops. That includes lettuce (ideal germination temperature is 75 degrees), spinach (70 degrees), peas (75 degrees) and beans (80 degrees).
To get an accurate read on how warm your soil is, try a soil thermometer (sold at garden supply centers). If your soil is too hot, cool it down with moisture and shade. Simply moisten the soil the day before you plan to plant. Also, sow larger seeds, such as peas and beans, a bit deeper than the recommended planting depth — the closer to the surface, the warmer the soil.
After sowing your seeds, cover the bed with shade cloth, or cover the planting area with a light layer of grass clippings, boards or cardboard. Moist soil is cooler than dry soil, and the covering will retain moisture while shading the soil, further reducing soil temperature. Keep the soil moist and covered, and check the planting daily until the seeds germinate; remove the covering immediately to let in light. (Shade cloth can remain on for a week or two to protect seedlings.)
You can also bypass direct seeding in hot soil by starting seeds indoors in pots. Transplant the seedlings to the garden several weeks later when the soil has cooled.
— Vicki Mattern, Contributing Editor
Photo by iStockphoto/Exxorian
Vicki Mattern is a contributing editor for MOTHER EARTH NEWS magazine, book editor and freelance magazine writer. She has edited or co-authored seven books on gardening, and lives and works from her home in northwestern Montana. You can find Vicki on Google+.