It’s almost Saint Patrick’s Day, the traditional planting date for peas. Should you sow on March 17?
Not if you live along the Front Range! While St. Patty’s Day may work fine for New England, it’s probably the wrong day to plant for much of the country.
If you live in a warm climate (E.g., parts of California, Florida, and Arizona), you are far too late. Peas should be planted as a winter crop, so they can grow while the weather is cool and humidity is higher.
And if you live here in the Pikes Peak area, mid-March is much too early. Sure, peas planted now may survive and grow and produce a crop. But they may also rot in too-cold soil, waiting for temperatures at which they can germinate.
As I write this, the high today is predicted to be in the mid 60s. I intend to dig out a t-shirt and go outside to muck around in the garden. But the upcoming weekend is expected to be cold—with lows around eleven and highs in the 20s. Plus, the forecast includes snow. Any pea seeds in the garden will just sit there and shiver.
Instead of relying on the calendar, try using a soil thermometer. Soils are much slower to react to spring’s weather extremes, and usually maintain an average of the dramatic swings air temperatures take at this time of year. Besides, you are planting seeds in the dirt, not in the air. Soil temperatures are a much more reliable indicator of when to plant.
There is an “official” way to take your garden’s temperature. If you don’t have a soil thermometer, you can buy one for under $10 at most garden centers. They are long, sturdy, and respond quickly. You don’t have to have a dedicated thermometer; it just makes the task easier.
According to Oregon State University, soil temperature should be measured at midday, while the Wisconsin extension service recommends taking readings in early morning. Whenever you measure, insert the thermometer about two inches below the soil surface for small and early seeds (including peas) and four inches for warm season crops such as squash and corn. (If it won’t go in that far, you have more serious problems than when to plant your peas!—or your soil is still frozen.) Wait a minute or two and read the results.
Peas can germinate in soils as cold as 41 degrees, but it takes them an average of 36 days (more than a month!) to do so. In the meantime, they can be eaten by birds and rodents, not to mention fungi and bacteria. By waiting until the soil reaches 50 degrees, that germination time is more than halved, to two weeks, and a higher percentage of the seeds will actually sprout. (Interestingly, peas sown in 77 degree soils germinate in only six days. However, the plants don’t grow well in days that warm.)
If your cold winters quickly turn into hot summers, squeezing in a pea crop can be difficult. In addition to choosing varieties that mature quickly, you can significantly reduce the time that peas have to be outside in the garden by germinating them indoors. Simply dampen some paper towels, spread the pea seeds across them, and roll them up. Slide the roll into a baggie to keep it damp, and place it in a nice snug spot. Here’s an opportunity to take advantage of that speedy sprouting at 77 degrees.
Check every day until the roots start to emerge from the seeds. Then plant them immediately. The roots are extremely brittle, so it’s vital that you place each seed carefully by hand. Orienting the seeds so that the roots point downwards is helpful but not essential—the plants will figure it out. The seeds should be buried 1 – 1½ inches deep.
Another option is to plant later in the season, and choose more heat-tolerant varieties. Read the packet or catalog descriptions to find which pea is best for your area. Peas can also be grown as a fall crop.
St. Patrick’s Day is an opportunity to have fun, watch a parade, and eat sugar cookies with green frosting on them. But you’ll probably have more peas from your garden if you find another day to plant them.