To Plant or Not to Plant?
Anyone who has traveled with children knows it is inevitable that a sweet voice will come from the back seat and ask the question “Are we there yet?” Sometimes repeatedly. Sometimes within a mile of the driveway.
The gardener’s version of this scenario is “Can we plant yet?”, usually asked far too early in the season, but who can blame people when the seed catalogs arrive in mailboxes in January with the tempting pictures and enticing descriptions? We all get tired of the snow and cold and want to rush things by getting outside to work in the soil. However, rushing does not yield good results.
Over the years, gardeners have utilized many methods to determine when to plant. The modern soil thermometer was not invented until 1714. One indicator used by gardeners of old was, “If you can sit on the ground with your trousers down, it’s safe to sow your seed.” Neighbors and law enforcement officials tend to frown upon that method today.
The Calgary Horticultural Society recommends using the common purple lilac as a natural calendar for your vegetable garden. “The leafing out of the lilac is a signal to sow cool-season vegetables such as lettuce, peas and spinach. When the lilacs bloom, it is time to fertilize the lawn and plant warm-season crops such as bush or runner beans and corn. Conventional wisdom has it that lilacs do not bloom until the risk of frost has passed, therefore it should also be safe at this time to plant out tomatoes, peppers and tender annuals. When the lilac flowers fade it should be warm enough to plant out squash and cucumbers.”
Research begun in the United States in the 1950s in both Montana and Idaho support the fact that the bloom time of the common purple lilac does not correspond to daylight, but is temperature driven. Heat radiating from a building can affect the bloom time of a lilac, so observe a bush at least ten feet away from any wall.
The United States Department of Agriculture (USDA) has developed hardiness zones for North America and has established guidelines. Our area is considered a Zone 5a so the average date of the last spring frost is May 3rd–May 9th. My totally unscientific experience, based solely on 60-some years of gardening, is that when Easter is late, spring planting will be late. Since Easter is not until April 20th this year, I would plan on the last frost date this year being toward the later part of that time frame.
Most cool weather can be planted around April 15th, assuming the ground can be worked and is not too wet. These vegetables include beets, carrots, radish, lettuce, spinach, peas, carrots, potatoes, and any of the cole crops (broccoli, cabbage, kohlrabi, cauliflower, and Brussels sprouts).
Warm season crops should not be planted until the soil is thoroughly warmed, usually May 15th – June 1st. These crops include corn, cucumbers, beans, tomatoes, peppers, eggplant, squash, and pumpkins. Memorial Day weekend is a great time to plant these crops.
So, the bad news is that it is indeed too early to plant yet. However, the good news is that you still have time to order or buy seeds and try some of the newer items on the market. Experiment with something new every year.
Carol Shirk
Certified Master Gardener