• BROOKINGS, S.D. - After a long winter, gardeners can be a bit too eager to get their vegetable gardens planted. Patience will pay off this gardening season said, Rhoda Burrows, Professor and SDSU Extension Horticulture Specialist.
• "Retail stores are filled with transplants of all types, and everyone is eager to get a head start on those homegrown tomatoes or the flower beds out front. But spring weather is often capricious, as is evidenced by the cold and even snow of this past week," Burrows said. "Even if night temperatures stay above freezing, clear nights can lead to frost, especially if the garden is in a low area."
• But frost is not the only consideration, explained Burrows pointing to the fact that warm season vegetables such as tomatoes, peppers and beans are chill-damaged at temperatures below 50 degrees, especially if the daytime temperatures also stay below 50.
• "Wait to plant these warm-loving crops until mid- to late-May, when night temperatures don't drop much below that 50 degree mark in your location. Watermelon and pumpkins can be planted in early June," she said.
• Burrows added that even most cool season vegetables such as peas, lettuce, or radishes don't grow well at temperatures below 45 to 50 degrees Fahrenheit. And if lettuce or cole crops such as broccoli or cauliflower are too large (stems bigger than a pencil width) when exposed to these lower temperatures for a few days, they may bolt rather than producing heads.
• The challenge explained Burrows is the fact that South Dakota gardeners must balance the slower growth at colder temperatures with the risk of hotter weather as the crop matures, which may decrease yield, cause bolting, or lead to bitter taste.
• "Bedding plants can also be damaged by spring frosts," she said. "You may want to leave them at your local garden center where they will be protected from the cold and buy them after the weather warms up again. Of course you can buy them and keep them in a protected location, like a garage, until the weather warms up."
• Graper reminded gardeners to be careful in selecting transplants, especially late in the season. "Avoid overgrown plants, with roots so dense that the soil is not visible along the sides when you gently remove the plant from the container. These plants will take longer to become established in your garden, and often have reduced yield," said David Graper, Director of McCrory Gardens and SDSU Horticulture Specialist.
• Burrows added that any transplant that has been growing in a greenhouse needs to be hardened off before planting into a garden.
• "This is accomplished by exposing the plant to full sun for gradually longer periods of time over about a week, so that it develops a thicker cuticle and is less likely to become sun- or wind-burned," Burrows said.
• More information on planting temperatures for your garden as well as recommended temperatures and the use of season extenders to protect plants from frost and cold temperatures can be found at iGrow.org, just click on the gardening tab and look for publication entitled "The Spring Warm up Begins."