Jack Frost

Saturday, November 6th, 2010 by Jenny Watts
    • Bulbs, bulbs, bulbs! It’s time to plant tulips, daffodils, hyacinths, crocus and many other flower bulbs for beautiful blooms next spring.
    • Crimson clover, fava beans and rye grass will fortify your garden soil over the winter. Seed these crops as you compost your summer vegetables.
    • Choose shade trees for fall color now and plant them while the soil is still warm.
    • Wildflower seed broadcasted with the first rains will take root over the winter and burst into flower next spring.

Frost in the Garden

It is common to have our first frost around the first week of October in Willits. However, that will vary depending on where you live. Areas near a lake, in valleys, or in the foothills can have quite different temperatures and frost conditions.

Since cold air is heavier than warm air, it sinks into the valleys, while hillsides may remain frost-free. Similarly, some parts of a particular property such as low areas may be more prone to frost than areas near warmer pavement or buildings.

The first frosts usually happen on calm, clear nights. During the day the sun warms the soil, and if the night is calm, and there are no clouds, heat rises as cold air sinks into the valleys. The temperature near the ground becomes cold and frost forms. These frosts often follow the passing of a cold front.

Since often there are a couple weeks or more of growing season after the first frost, if you can minimize the effects of this frost you can get more enjoyment from flowers and a longer harvest season.  Here are several methods to protect tender plants from frost.

The key to good frost protection is to trap the warm air from the ground in a tent over the plants. Woven fabrics are better than solid ones such as plastic. “N-Sulate” is a special white fabric you can find at nurseries just for frost protection.

A lighter weight fabric, gives about 2 degrees protection, while the thicker one gives up to 5 degrees protection. If possible, support the material so it doesn’t rest directly on the plants.  Apply covers in early evening as winds die down, and remove the next morning as the sun warms the plants.

One easy method to afford some frost protection is irrigation. Moist soil can hold up to four times more heat than dry soil, keeping the air above it about five degrees warmer. So water well before a frost.  

Spray citrus and other tender plants with Cloud Cover to give them some protection from frosts. Cloud Cover is a product that holds moisture in the leaves and reduces stress caused by temperature extremes. Frost tender plants have about 3 to 5 degrees more frost resistance than untreated plants.

If you can’t protect sensitive crops like tomatoes, harvest them early.  They will ripen in the kitchen, or you can pull up the whole plant and hang it upside-down in the garage, and they will continue to ripen slowly.

Tender crops that can’t withstand frost include tomatoes, eggplant, peppers, beans, cucumber, sweet corn, squash and melons. Cool-season crops such as cabbage, broccoli, onions, parsley, radish, spinach, turnips, and Brussels sprouts will withstand a hard frost.

Plan ahead to be ready for the first frost and prolong your gardening season.