It’s best to wait for 55-degree nights to plant tomatoes

Home gardeners often seem to be in a race to see who plants their tomatoes first. If the weather in March is warm enough, tomatoes and other heat-loving summer vegetables that get an early start can be ripe by mid-May. But if the weather remains cool through March, early transplants and seedlings will not grow well and may take a little longer to recover their vigor. Waiting a few weeks to plant, until nighttime temperatures are reliably above 55 degrees, guarantees better crops and healthier plants.

Tomato drop their flowers when nighttime temperatures are less than 55 degrees or days are above 90 degrees. Hormone sprays help set flowers when temperatures are too low but not during hot weather. Keep hot caps or water walls (plastic cells that are filled with water and wrapped around transplants) at hand to shelter tomato transplants on cooler nights or use heat-retaining row covers to trap daytime heat.

Cold wet soil will rot bean seeds or really slow germination. Sow bean seeds when soil temperatures remain above 50 degrees and when the soil is slightly moist, not wet.

Bush beans mature earlier than pole type. This is important to remember because beans stop setting or drop flowers during hot weather and our first long hot spell often occurs in early May.

When buying bean seeds for spring planting look for varieties that mature earlier. Burpee’s Early Bush Italian matures in 50 days; Blue Lake pole beans are ready to eat in 55-65 days. Pole beans produce over a longer season and take up less space in the garden since they are planted on trellises or poles. Plant a row of bush bean seeds every two weeks to extend the harvest.

Seeds for a second crop of early maturing beans can be planted in late August as summer temperatures moderate. The second crop should be ready to eat in late October.

Most cucumber varieties require pollination by bees (as do melons and squashes). Cucumbers also drop flowers during hot weather. Parthenocarpic varieties do not require pollination-the flowers are all female and the fruit is seedless unless cross pollination occurs. Parthenocarpic varieties including John Scheeper’s ‘Silor Mini” (60-65 days) can be planted earlier in spring when bees are less active. ‘White Wonder’ is an heirloom cucumber, not self-pollinating, that tolerates high heat and matures early (35-60 days). It will be ready for pollination when the bees are.

Eggplants and peppers thrive in hot weather and produce fruit throughout a long growing season. Setting out transplants in cooler spring weather will slow or stop root and plant growth. Use row covers to maintain a warmer micro-climate and hot caps to keep eggplants and peppers warm at night if planting during cooler spring weather.

Eggplant seeds germinate quickly when daytime temperatures are between 70 and 90 degrees. Maturation dates for both peppers and eggplants tend to be about 70 to 90 days. Seeds for peppers and eggplants can be started indoors now and will be ready for transplant in 6-8 weeks.

Pest insects are attracted to stressed plants and planting too soon in the season will stress your summer vegetables. Monitor plants for aphids and whiteflies and wahs them off plants or apply insecticidal soaps to control pest insect populations.

This story was originally published March 16, 2017 at 12:31 AM with the headline "It’s best to wait for 55-degree nights to plant tomatoes."