Don’t get tempted by planting bug or frost might bite you
The warm sunny days of early spring are a welcome respite from the long cold winter. But don’t let the warm daytime temperatures fool you into thinking that Mother Nature doesn’t have any more cold weather up her sleeve for central Ohio.
I urge you to think twice about planting annual flowers such as geraniums and impatiens or warm-season vegetable crops such as tomatoes and peppers before early to mid-may. I tend to think of Mother’s Day as the earliest that we should be planting these plants in central Ohio.
The potential for cold weather
The average date of the last spring frost in Columbus is April 29 but remember this is an average date based on historical climate data for Columbus. The probability of a frost occurring after April 29 is 30%, and many years we experience frost into mid-may. Last year, we experienced the last spring frost on May 9 and, in 2019, the last frost occurred on April 2, so as is always the case, variability is the rule with weather.
Frost occurs when air temperatures reach 32 degrees Fahrenheit, but because it is colder closer to the ground, a frost can occur even when air temperatures are above freezing. A light freeze (or frost) occurs from 29 degrees to 32 degrees and will damage or kill tender young plants. A moderate freeze occurs from 25 degrees to 28 degrees and will cause damage to many plants, including new growth on trees, shrubs and perennials. A severe freeze occurs at temperatures below 24 degrees and causes widespread damage to nearly all plants.
Plant cool-season crops now
As an eager gardener itching to plant something, you don’t have to wait until the danger of frost is past to begin planting certain crops. For early spring color, feel free to transplant pansies, viola and even snapdragons until it is safe to plant less-hardy summer annual flowers. Once the soil temperatures reach 40 degrees it is safe to direct-seed cool-season crops in the vegetable garden. Coolseason crops include lettuce, collards, spinach, beets, carrots, onions, peas, parsnips, radishes, turnips and others.
Transplants of other cool-season crops such as kale, kohlrabi, broccoli, cabbage and cauliflower can also safely be planted into the garden in April.
For warm-season garden favorites such as tomato, summer squashes, beans and sweet corn, wait until soil temperatures reach 60 degrees consistently before sowing seeds. Plan on waiting until three weeks after the last frost to plant very tender vegetables such as eggplant, watermelon, winter squashes and cantaloupe.
Protect plants in cold weather
Be ready to protect young plants when cold weather is forecast. Covering plants with fabric row covers available at garden centers, bedsheets, or even newspaper, can protect vulnerable plants from frosts and even light freezes. Plants in small containers can be moved into a garage or shed to protect them from the cold. Many times, microclimates around buildings and other structures serve as a buffer and protect plants from light frosts in late spring.
Gardening is like dancing with Mother Nature, and when you dance with Mother Nature you always let her lead! So be ready to adjust when that lateseason frost occurs.
Mike Hogan is an associate professor at Ohio State University and extension educator at the OSU Extension.
hogan.1@osu.edu