Peppers require patience -- and warmer soil

These young plants need warm soil to thrive and produce peppers. (Photo: Kathy Morrison)

There’s a reason you should hold off transplanting peppers until April (or May): It’s too darn cold!

Many local gardeners have been tempted to plant peppers, tomatoes and other summer stalwarts. These seedlings have been appearing in local stores and nurseries – it must be planting season!

But wait; your peppers will thank you for your patience.

Even though the sun has been shining and Sacramento saw several recent days in the 70s, overnight lows and soil temperatures remain chilly. After all, it’s still winter (for a few more days).

Tuesday’s low temperature dipped down to 34 degrees in Sacramento. Neighboring communities, particularly in the foothills, saw late frost.

Pepper seedlings will die at 32 degrees. So even if they didn’t freeze this week, they’re not happy outdoors.

It’s not just the air temperature that affects their health and growth; it’s the soil temperature that can make all the difference.

According to UC Cooperative Extension master gardeners, pepper plants need warmer soil and air temperatures to thrive. Air temperatures below 55 degrees can stunt pepper growth and development. As of 2 p.m. Tuesday, it was only 55 degrees in Sacramento, even under sunny skies.

And the soil temperature? According to Farmer Fred Hoffman (who keeps track at his www.farmerfred.com website), Sacramento’s soil temperature is still about 50 degrees; 46 degrees in the foothills.

Peppers need soil temperatures above 60 degrees to grow healthy roots. Transplanted into such cold soil, pepper seedlings just sit there and sulk. In fact, a cold start may be detrimental to the pepper plant’s overall health and keep it from producing up to its potential.

The answer? Besides waiting to plant in April when the soil is warmer, give your extra-early seedlings some added warmth.

Surround them with mulch (making sure to leave a 4-inch circle of clear space around the main stem to prevent rot). The mulch acts like a big heavy blanket over the soil, soaking up heat during the day and holding it in overnight.

Also, give your peppers their own little greenhouses with “hot caps.” Available at nurseries, hot caps are waxed paper or plastic tents that can be placed over individual plants to hold in warmth. Plastic row covers serve the same purpose, covering multiple plants at once.

Clear (not white) plastic one-gallon milk or water jugs can work as mini-greenhouses, too. Cut off the bottom of the jug and place it over the plant with the neck side pointed up. Keep the lid off the jug so the plant can breathe.

Peppers planted in containers warm up quicker than in soil, so that’s another option for early-bird pepper planters. But an extra-early start usually will not produce extra-early peppers in Sacramento – unless they’re growing in a greenhouse.

For more master gardener tips on peppers: http://ipm.ucanr.edu/PMG/C604/m604yi01.html