Tomato plants need lots of sun to thrive

Jeanne Crisp and Julie Kelly

Summer just isn't summer without the juicy vine-ripened tomatoes, a favorite for gardeners everywhere, whether grown in a garden or container on the deck. Here are a few tips for a successful harvest.

If you started tomatoes from seeds, you should transplant the starts when nighttime temperatures stay above 50 degrees. In this area, that is typically around the middle of May to early June. If you buy plants, look for short season varieties with "days to maturity" of 75-80 days or less. Resist those tempting giant varieties – you'd be lucky to have 2-3 reach maturity in our climate.

There are two basic types of tomatoes. Determinate varieties are bush-like with fruit that ripens over 4 to 6 weeks, while indeterminate varieties are vine-like and continue to grow and produce tomatoes until the end of the season. Dwarf indeterminate tomatoes are a recent introduction that provide a long season of tomato production on a shorter and stockier plant and are great for growing in containers.

Whether planting into the ground or into containers, choose a site where they will receive a minimum of 6 hours of sun per day. Set plants 2 to 3 feet apart in well-drained soil and water well to promote deep roots. To encourage root development and a healthier plant, bury up to 6 inches of the stem as you plant the tomato. Black 5-gallon buckets are great containers to grow tomatoes because the black soaks up heat and tomatoes thrive in warm soil. Be sure to drill 4 to 6 drainage holes in the bottom of the buckets before planting. 

When you plant you should also provide stakes or cages to support the plants as they grow heavier with increased leaf canopy and fruits.

Staking the vines also promotes good air circulation and keeps slugs and snails from damaging the plants. Inserting stakes or cages after planting will only damage the tomato plant.

Water your tomato plants thoroughly at the base twice a week. Tomatoes in containers may need more frequent watering. Try to keep the foliage dry to prevent the spread of disease.

Once the heat of summer arrives, mulch the tomatoes to discourage weeds, retain moisture, and reduce disease. Prune axillary shoots (suckers) for a more manageable plant size and larger fruit.

Suckers are the leafy shoots that emerge from the joint between the branches and the main stem of the plant. If left on the plant, suckers divert water and energy that would otherwise be used for fruit development. Also, regularly monitor plants and promptly remove any diseased plant material.

Starting in mid- to late-August, remove blossoms and small fruit to encourage ripening of the remaining tomatoes. You can also reduce or stop watering to stress the plant and encourage ripening.

Success with tomatoes varies from year to year, usually in relation to the weather, so just have fun and don't get discouraged. Try different varieties and record the results, so you can replicate your success or avoid any failures when the next season comes around. If you have specific questions about your vegetable, contact us at gardenadvice@mukilteogarden.org.

Happy planting!