From Dennis Patton:
Gardeners often try to get a jump on the season by planting tomatoes as early as possible. There just seems to be something about being the first in the neighborhood to pick a red ripe tomato. Caution should be taken if you are one of those season jumpers. Early planting can be successful if there are certain precautions that are followed, especially this year with the cool spring conditions we have been experiencing.
Tomatoes need adequate soil temperature before they will even start to grow. Tomato roots do not do well until soil temperatures reach a fairly consistent 55 degrees F. You can use a soil thermometer to check the temperature at 2 inches deep during the late morning to get a good average temperature for the day. As of last week most soil temperatures in Kansas are now in the upper 40's. Plastic mulch can be used to warm soil more quickly than bare ground. Plastic mulch should be laid at least four to six weeks prior to planting to warm the soil. Simply rolling out the plastic and planting does not provide any advantages. If your plants develop purple leaves it is a sign of phosphorus deficiency due to cool soils.
The first step in planting tomatoes is to harden off the plants. Plants moved directly from a warm, moist greenhouse to the more exposed, cooler conditions outside will undergo transplant shock. Transplant shock causes plants to stop growing for a time. It is sometimes difficult to kick-start the plants and get them growing again. Plants can be acclimated to outside conditions by placing them outdoors in a location protected from wind and full sunlight for a few days before transplanting.
When planting early there should be some protection from frost. Tomatoes cannot tolerate frost. Though we are past the average date of the last frost, watch the weather and cover the plants if frost threatens. Remember a couple of years ago it snowed in early May. A floating row cover or light sheets can be used for protection. Actually a floating row cover can be left on the plants for two to three weeks to increase the rate of growth and establishment.
Here are a few other tips for getting tomato plants off to a fast start:
1. Use small, stocky, dark green plants rather than tall, spindly ones. Smaller plants form roots rapidly and become established more quickly than those that are overgrown.
2. Though tomatoes can be planted slightly deeper than the cell-pack or pot, do not bury the plant deeply or lay the stem sideways unless the plant is very leggy. Though roots will form on the stems of tomatoes, this requires energy that would be better used for establishment and growth. I know a lot of old-time growers swear by burying the plants but it is not proven to provide any benefits and slows establishment. Slowed establishment means a longer wait for the first harvest.
3. Use a transplant solution (starter solution) when transplanting to make sure roots are moist and nutrients are readily available.
4. Do not mulch until the plant is growing well. Mulching too early prevents soil from warming up.
Get ready, tomato planting is just a few weeks away. I personally like to plant my tomatoes on Mother’s Day weekend. What a great gift.