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Sub-freezing temperatures in Sacramento forecast

Protect your sensitive plants from frost

Sacramento Digs Gardening
BY Debbie Arrington PUBLISHED JAN 25, 2021

Small citrus tree with frost blanket and lights

This display from the Fair Oaks Horticulture Center a few years ago illustrates how to protect

citrus trees, especially smaller ones, from frost damage. The frost blanket of course would be pulled over the tree to the ground in practice. The chart on the right is a guideline that lists temperatures below which mature citrus trees can be damaged. See the note below for details. (Photos: Kathy Morrison)

Time to pull out the frost blankets!

After months of expecting “possible” frost, the threat of subfreezing overnight temperatures is finally real. According to the National Weather Service, Sacramento could see 29 degrees just before dawn on Tuesday morning. That follows a very chilly night with an expected five to six hours under 32 degrees.

Frost damage occurs when temperatures stay below freezing for more than two hours. So, take precautions this evening:

* Cover your sensitive plants with frost cloth, blankets or cloth sheets (not plastic). Ideally, do this before sunset so radiant heat will help keep plants cozy.

* Remember to uncover plants during the day (especially if it’s sunny) or they can be smothered by their frost protection.

* Harvest ripe citrus that may be harmed by frost. Don't let oranges, lemons and other fruit freeze on the tree.

* Citrus trees (particularly young trees) tend to be susceptible to frost damage. Limes are the most frost-tender. Make sure they get some protection before frost hits.

* Wrap trunks of young citrus trees to insulate them from frost.

These C9 Christmas lights can help protect citrus trees.

* Holiday lights – the old-fashioned kind that get hot, not LEDs – can help keep plants warm, too. Wrap a string of lights around the trunk and branches. Keep the lights on all night.

* With some exceptions, keep plants watered. Frost injury occurs when ice crystals form on leaf surfaces and draw moisture out of the leaf. The damage from dehydration is what causes frost burn.

* The exception to this rule are cactus and succulents, where saturation can cause more damage. Also, such tropical plants as bananas and hibiscus may rot if over-saturated before frost, so they prefer to be kept on the dry side.

* Don’t overprotect. Plants are more frost resistant if they’ve experienced some cold weather and winter hardening.

* If frost damage occurs, wait until March or April to prune off browned branches. That injured area will help protect the rest of the plant from further frost burn.

Note: Mexican limes are the most vulnerable (29 degrees), followed by Bearss limes (28), Eureka or Lisbon lemons (26), grapefruit (25), Meyer lemons (22), sweet oranges such as navels (21), mandarins/tangerines (20) and kumquats the hardiest (19 degrees). Damage also depends on the duration of exposure to cold.

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succulents gardening Sacramento frost tropical plants frost blankets tender plants citrus trees January irrigation weather

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Garden Checklist for week of May 19

Temperatures will be a bit higher than normal in the afternoons this week. Take care of chores early in the day – then enjoy the afternoon. It’s time to smell the roses.

* Plant, plant, plant! It’s prime planting season in the Sacramento area. If you haven’t already, it’s time to set out those tomato transplants along with peppers and eggplants. Pinch off any flowers on new transplants to make them concentrate on establishing roots instead of setting premature fruit.

* Direct-seed melons, cucumbers, summer squash, corn, radishes, pumpkins and annual herbs such as basil.

* Harvest cabbage, lettuce, peas and green onions.

* In the flower garden, direct-seed sunflowers, cosmos, salvia, zinnias, marigolds, celosia and asters.

* Plant dahlia tubers. Other perennials to set out include verbena, coreopsis, coneflower and astilbe.

* Transplant petunias, marigolds and perennial flowers such as astilbe, columbine, coneflowers, coreopsis, dahlias, rudbeckia and verbena.

* Keep an eye out for slugs, snails, earwigs and aphids that want to dine on tender new growth.

* Feed summer bloomers with a balanced fertilizer.

* For continued bloom, cut off spent flowers on roses as well as other flowering plants.

* Don’t forget to water. Seedlings need moisture. Deep watering will help build strong roots and healthy plants.

* Add mulch to the garden to help keep that precious water from evaporating. Mulch also cuts down on weeds. But don’t let it mound around the stems or trunks of trees or shrubs. Leave about a 6-inch to 1-foot circle to avoid crown rot or other problems.

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