Protecting plants from the cold

Gardeners face myriad challenges, as rain and cold are a distinct possibility during an El Niño season. Good judgment on tree selection and pruning shows during and after major winter storms.

In certain Laguna climes, there is the possibility of frost damage to orna- mentals and fruit trees. Unantici- pated wet and cold weather conditions may damage strawberries, early tomatoes and basil. Cold temperatures damage or destroy certain plant tissues by causing the water inside the plant to crystallize and damage the cell walls.

Many of our tropical and subtropical plants can suffer cold damage once temperatures drop below 40°F. Maceration of the plant tissue causes the protoplasm inside the cells to burst out, causing the mushy look of soft tissue plants and the burnt, limp feel of leaves.

Many gardeners believe that they can keep plants warm by wrapping them up, just as we wear heavier clothing in cold weather. This, however, does not hold true. Plants have no body warmth. Within a few hours they will be just as cold as if they had no protection.

One should know the lowest temperature their plants can tolerate. Plants cannot be expected to survive outdoors with any amount of covering during freezing conditions. Only artificial heat indoors will sustain them.

What can you do if your non-hardy plants are too large to move into the garage? If the plants are movable, try temporarily relocating them under the eaves of your house. This location is warmer and less exposed to the elements.

You may reduce the loss of heat by completely covering plants with cloth tarps or burlaps. The corners are then pegged into the ground.

If this is undertaken at sundown, the radiant heat of the soil will keep space around the plants warmer than the outside air temperature.

As last resorts, portable heaters and fans can keep temperatures from falling too low around sensitive plantings. This isn’t very practical when it is raining, because of the danger of water near electricity.

During periods of clear, cold weather, sprinkling plants lightly with water will often save them. If the temperature is below freezing, however, sprinkling will do more harm than good. Perhaps the best solution is to know what zone you live in (the Sunset Book is an excellent guide) and how low temperatures might drop.

Finally, do not rush the planting of cold-sensitive flowers and vegetables winter ends.

Armed with this information, you can plant hardy perennials for your locale.

See you next time.

STEVE KAWARATANI is married to writer Catharine Cooper. He can be reached at (949) 497-8168, or e-mail to plantman2@mac.com .