Wednesday, March 9, 2011

Have You Taken Your Temperature?

The temperature of your garden soil is key to successful seed germination in your garden. As different types of seeds germinate at different temperatures, measuring the soil temperature can guide your vegetable planting schedule.

Bill Mansour, retired vegetable crops specialist for the Oregon State University Extension Service, recommends the following method for taking an accurate temperature reading of your garden soil.

Use a probe thermometer, available at garden supply stores.

Insert the thermometer to two inches into the soil for early season and small, seeded vegetables including arugula, fava beans, beets, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, kale, leeks, lettuce, many of the oriental greens, onions, parsnips, peas, radicchio, radishes, spinach, Swiss chard and turnips.

Insert the thermometer four inches for warm season vegetables such as tomatoes, eggplants, peppers, cucumbers, squash, corn and melons.

Take the temperature at the same time each day for several days in a row and average them out. The best time to take the temperature is mid-day. If you can't take the soil temperature each day, agricultural weather reports give out soil temperature information taken mid-day.

"You can have fun graphing the maximum, minimum and mean temperatures and get a feel for how soil temperatures fluctuate daily," said Mansour.

"Start thinking about planting cool season crops when soil temperature averages at least 40 degrees and warm season crops when the average is 50 degrees or more," he advised. "But remember, you also have to consider is the risk of killing frost after your seeds emerge."


Aer Conditionat said...

This is a great article. Thanks for taking the time to write it. I never knew that you have to take the soil’s temperature in order to plant some seeds. Thanks again.

Elaine said...

I hate to say it, but living where I do we don't really have to worry about the temp of the soil for seed germination. I am sure the rest of the country does though and it is a great post! I like you you can use a tool that you probably already have in your kitchen.

mike509 said...

I refrigerate cleome and morning glory seeds before "starting".... and keep others on a heating pad. Great article - important stuff! I "don't" use a thermometer though.... :)