Lettuce is a cool season crop. Transplanting lettuce to your garden will get a jump-start on the season. However, the soil temperature needs to be warm enough for the roots to grow. This segment shows how to help cool season crops become well established.

Produced by the Department of Communications at Kansas State University. For more information, visit our website at: http://www.kansasgreenyards.org

Transplanting Lettuce to the Garden

The main advantage of transplants is that they’ll mature earlier. Therefore, if you have a cool season plant that doesn’t do well in the summer, a transplant will mature and produce before the hot part of the summer where the cool season plants will go downhill.

The black plastic is designed to warm the soil. I’m putting the plants in early, and I want to make sure that the soil temperature is at the point where the roots can become established. If they aren’t, and the soil temperature is too low, the plants will just sit there, and the roots won’t grow.

I’ll be planting a plant every twelve inches. Later, a second planting will be placed in-between the original plants. First, cut the plastic with a knife in an “X” shape, and make an opening for the plant. Dig into the soil, place the plant into the hole, and firm the soil around the plant. And finally, add about a cup of transplant solution to make sure that you have good contact between the soil and the root system. The added moisture also helps make the roots can grow.

The soil temperature is determined by using a soil thermometer. A soil thermometer allows you to determine what the soil temperature is with an instrument that has a metal core so that it doesn’t break when you push it into the soil. By using the black plastic, it increases the soil temperature higher than without the protective cover.

The easiest way to check that is to push it through the black plastic and into the soil. It may take a short time to equilibrate, but the temperature it’s showing is 65 degrees. When the thermometer is moved to normal soil, the temperature will be much lower – somewhere between 55 and 60 degrees. So, we have a warmer temperature under the black plastic that will allow the roots to become established quicker. The normal ground temperature between 55 and 60 degrees is warm enough to establish roots, but it changes during the day. In he morning, the temperature will be much cooler on normal soil, and much warmer under the plastic – and that’s what makes the difference. It’s important to have a warm temperature for the roots.

Later, if we still have plants here during the warm part of the summer, it’s a good idea to cover the plastic with organic mulch because it may get the soil too warm. The energy from the sunlight needs to be cut off, and an organic mulch will help to block the sun.

This feature story prepared with Ward Upham, Kansas State University Research and Extension Research Assistant. For more information, visit your local county extension office or visit our website at KansasGreenYards.org.

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