Sacramento Digs Gardening logo
Sacramento Digs Gardening Article
Your resource for Sacramento-area gardening news, tips and events

Articles Recipe Index Keyword Index Calendar Twitter Facebook Instagram About Us Contact Us

Threat of widespread frost threatens new growth

Flavor of oranges may actually get a boost from 'kiss of cold'

Our warmer afternoons have prompted some fruit trees to push out blossoms already, such as on this multi-grafted fruit salad tree, photographed Feb. 11 at the Fair Oaks Horticulture Center. But freezing temperatures could threaten any eventual crop.

Our warmer afternoons have prompted some fruit trees to push out blossoms already, such as on this multi-grafted fruit salad tree, photographed Feb. 11 at the Fair Oaks Horticulture Center. But freezing temperatures could threaten any eventual crop.

Kathy Morrison

Our afternoons may feel like spring, but frost danger is still in our forecast. And that creates some challenges for Sacramento-area gardeners: All that tender new growth may need protection.

The National Weather Service warns of “widespread frost” on Thursday and Saturday morning in the greater Sacramento area and foothills. Overnight lows are expected to dip into the low 30s if not below freezing.

Frost threatens not only new shoots but tender blossoms and buds. Sacramento reached 71 degrees on Sunday, Feb. 12. Such warm weather coaxed out early blooms on some fruit trees. Frost can cause those blossoms to fall quickly without setting fruit.

Likewise, frost can burn newly rooted cuttings or transplanted seedlings – even if the temperature stays above 32 degrees. Protect these babies with row covers or “hot caps” – mini-greenhouses made of waxed paper or improvised with plastic milk jugs (with the bottom cut out).

A clear night with no wind can actually produce more frost damage than a windy night at the same temperature. According to university research, foliage temperatures on citrus trees were three to four degrees lower than surrounding air temperature on clear, windless nights. So, 34 degrees could actually feel like 30 to a tender lime or lemon. Young trees are most susceptible to cold damage.

Most citrus is OK down to 30 degrees. Some “chill hours” – time spent under 45 degrees but above freezing – may actually improve the flavor and quality of ripening oranges. That “kiss of cold” brings out the sugars while toughening the skin, extending the fruit’s longevity on and off the tree.

One of the easiest ways to protect sensitive plants: Water. Irrigate your garden before a frost warning; moist soil radiates heat and offers some frost insurance. (The exception are succulents; they soak up that extra moisture and can actually burst if their cells freeze.)

What if a tree or shrub has already suffered frost damage? Leave it on the plant for a few more weeks; it can protect the plant from further damage.

This frost warning is later than usual for Sacramento. After decades of recommending a “last frost” date of mid March, most experts now cut off our frost period at the end of January. According to the Sacramento County master gardeners, our average last frost date is Jan. 27.

But in 2022, Sacramento hit 32 degrees on Feb. 24 and dipped down to 35 degrees on March 6. Our latest ever freeze on record (30 degrees) hit March 27, 1898.

Surrounding communities need to watch out for frost and freeze much later than Sacramento with some areas under threat well into spring. The master gardeners list last frost dates for Marysville (March 16), Lodi (March 31), Woodland (April 1), Auburn (April 13), Davis (April 18), Placerville (May 18) and Nevada City (June 4).

For more tips on frost protection:


0 comments have been posted.

Newsletter Subscription

Sacramento Digs Gardening to your inbox.

Local News

Ad for California Local

Dig In: Garden Checklist

For week of March 26:

Sacramento can expect another inch of rain from this latest storm. Leave the sprinklers off at least another week. Temps will dip down into the low 30s early in the week, so avoid planting tender seedlings (such as tomatoes). Concentrate on these tasks before or after this week’s rain:

* Fertilize roses, annual flowers and berries as spring growth begins to appear.

* Knock off aphids with a strong blast of water or some bug soap as soon as they appear.

* Pull weeds now! Don’t let them get started. Take a hoe and whack them as soon as they sprout.

* Prepare summer vegetable beds. Spade in compost and other amendments.

* Prune and fertilize spring-flowering shrubs after bloom.

* Feed camellias at the end of their bloom cycle. Pick up browned and fallen flowers to help corral blossom blight.

* Feed citrus trees, which are now in bloom and setting fruit.

To prevent sunburn and borer problems on young trees, paint the exposed portion of the trunk with diluted white latex (water-based) interior paint. Dilute the paint with an equal amount of cold water before application.

* Cut back and fertilize perennial herbs to encourage new growth.

* Seed and renovate the lawn (if you still have one). Feed cool-season grasses such as bent, blue, rye and fescue with a slow-release fertilizer. Check the irrigation system and perform maintenance. Make sure sprinkler heads are turned toward the lawn, not the sidewalk.

* In the vegetable garden, transplant lettuce and kale.

* Seed chard and beets directly into the ground.

* Plant summer bulbs, including gladiolus, tuberous begonias and callas. Also plant dahlia tubers.

* Shop for perennials. Many varieties are available in local nurseries and at plant events. They can be transplanted now while the weather remains relatively cool.

Contact Us

Send us a gardening question, a post suggestion or information about an upcoming event.