Protect Frost-Tender Plants

From The Fresno Bee, November 26, 2009:

By Elinor Teague

Our first frost of the year was right on schedule. The average first frost date here in the Central Valley is Nov. 15; some low-lying valley areas experienced freezing temperatures on Nov. 16 this year.

In our dry, arid, desert climate, we can expect frost on winter nights when we can see the stars. Rain clouds that cover the stars and the fog that follows the rain here in the Valley act as heat-retaining blankets that prevent the Earth's surface heat from dissipating into the upper atmosphere so that temperatures drop below freezing.

Identifying those plants in the garden that are frost-tender and knowing at what temperatures they will suffer severe or irreversible damage helps us plan protective measures. Tropical plants such as canna [my cannas were nipped by the frost, see picture], elephant ears, hibiscus and some varieties of bougainvillea will be severely injured or killed when temperatures remain near freezing (32 degrees) for hours.

If the weather report indicates that early morning temperatures will hover around the freezing mark, cover tropical plants with frost blankets, burlap, or old towels before going to bed. Plastic sheeting does not provide frost protection.

Subtropical plants such as Australian ferns, some succulents (Jade plant) and avocado trees should survive a near-freezing night with minimal damage and can tolerate short periods of freezing or below-freezing.

Cover subtropical plants or use UL outdoor-related twinkle lights to keep them warm when temperatures are to fall below 32 degrees. Always remove any covering during the day. Irrigate the soil around frost-tender plants for a day or two.