After a Freeze, What Should a Gardener Do?

After several days of bone-chilling mornings with temperatures dipping into the low-to-mid twenties, should shivering gardeners:

a) remove all plants that look frost-bitten; 

b) prune away all freeze-damaged plant parts;

                   

c) Purchase and plant again this weekend those same varieties of trees, shrubs, perennials and annuals;

                 

d) If it isn't raining, water the garden, even if the plants resemble toast;

            

e) fight the urge to prune and plant by staying indoors, next to the wood stove.

The answers happen to be the easiest to accomplish on a cold weekend: d) and e).

Even if plants in your garden look blackened and wilted now, new growth may emanate from the base of the plant when the weather warms up in a couple of months.

New growth beneath the frosted branches of a geranium.

Pruning away the dead portions now exposes buds that may still be alive; another frosty morning could wipe out those survivors. 

The average frost season for Sacramento is about two months, primarily December and January. But temperatures below 32 have been recorded as early as the first week in November; as late as the third week in March.

So, keep the shears in the garage and let the dead portions of the plants protect the understory. It may take until mid-Spring before you see new growth; patience is key before you pick up the pruners.

Make sure your garden and potted plants remain moist. Water gives off heat, and this can protect plants from freezing, especially borderline citrus trees, such as lemons and limes. Damp soil retains heat better than dry soil, protecting roots and warming the air near the soil.

It's dead, Jim.

Some of those dead plants may be summer annuals, such as this impatiens, which took its sweet time to croak. Mornings hovering around 25 degrees can do that to a summer annual. Put them in the compost pile; plant more in the spring, after all danger of frost.

Frosty the Ficus

And what about those plants that have frozen past the point of no return? Should you replace them with the same varieties? That frozen ficus may be Mother Nature's way of telling you: "Hey! This ain't San Diego! Pick outdoor plants that can take colder temperatures!"

Dead Foliage? Leaf It Alone!

 



When this...










 

Becomes this...









Don't be too quick to prune out the dead stuff this time of year. Lurking below all that dead foliage on geraniums, pelargoniums, alstroemeria and hydrangeas, there may be this...



 


New growth, emanating from near the base.









It's still winter; more frosts are possible. In Sacramento, there's a 10% chance of frost until March 23. And that dead foliage offers some protection to that new growth from freezing temperatures.

So, although the temptation is great to "tidy up" in February, give those plants a chance, even if you don't see new growth right now. Some perennials won't sprout new growth until mid-spring.

And "plant insurance" for tender perennials can be purchased in late summer-early fall. 

 

Start cuttings of those plants and keep them in a warm, well-lit area until planting time the following spring. Then, if that perennial in the ground does bite the dust, you have a quick replacement. 





A good book on the subject is The American Horticulture Society's Plant Propagation book.

Frost date range (10% chance) for select California locations:
 

Bakersfield: Nov. 20-Mar. 3
Chico: Oct. 30-Apr. 23
Eureka: Nov. 15-Mar. 14
Fresno: Nov. 7-Apr. 1
Lakeport: Oct. 10-May 10
Livermore: Nov. 3-Apr. 27
Lodi: Nov. 2-Mar. 31
Los Angeles: Jan. 2-Jan. 3
Marysville: Nov. 14-Mar. 16
Modesto: Nov. 10-Mar. 20
Napa: Nov. 9-Apr. 20
Nevada City: Sept. 24-June 4
Placerville: Oct. 22-May 18
Sacramento: Nov. 14-Mar. 23
San Francisco: Dec. 1-Feb. 9
San Jose: Nov. 23-Feb. 19
Santa Rosa: Nov. 5-May 1
Sonora: Oct. 26-May 10
Stockton: Nov. 5-Mar. 30
Truckee: July 31-July 27
Ukiah: Oct. 25-Apr. 29
Vacaville: Nov. 4-Apr. 24
Willows: Nov. 8-Apr. 23
Winters: Nov. 13-Mar. 27
Woodland: Nov. 5-Apr. 1

And for those that feel lucky, the frost date range when there is a 50-50 chance of freezing temperatures:

Bakersfield: Dec. 11-Jan. 31
Chico: Nov. 15-Mar. 20
Davis: Nov. 24-Mar. 4
Eureka: Dec. 15-Jan. 30
Fresno: Nov 25-Feb. 22
Lakeport: Nov. 2-Apr. 20
Livermore: Nov. 13-Mar. 29
Lodi: Nov. 16-Mar. 6
Los Angeles: rare
Marysville: Dec. 2-Feb. 9
Modesto: Nov. 29-Feb. 21
Napa: Nov. 26-Mar. 20
Nevada City: Oct. 15-May 17
Placerville: Nov. 6-Apr. 25
Sacramento: Dec 1-Feb. 14
San Francisco: Jan. 5-Jan. 8
San Jose: Dec 25-Jan. 22
Santa Rosa: Nov. 19-Mar. 25
Sonora: Nov. 12-Apr. 14
Stockton:Nov. 22-Mar. 1
Truckee: Aug. 16-July 11
Ukiah: Nov. 10-Apr. 3
Vacaville: Nov. 18-Mar. 19
Willows: Nov. 23-Mar. 14
Winters: Nov. 27-Feb. 17
Woodland: Nov. 26-Feb. 28

Prune Tomato Flowers? No!

One question I have been getting a lot of lately: Should I prune off  (snip off, pinch out) the first tomato flowers that appear, in order to get more tomatoes later?

Those early tomato flowers, especially if the weather doesn’t cooperate, will fall all by themselves, thank you. Your assistance is not needed.

Flower drop and tomato fruit set failure can happen in May and June for a number of reasons, including night temperatures below 55; daytime temperatures above 90; excess nitrogen fertilizer, too much shade, too much smog, plants set out too early in spring, or planting the wrong variety for your area (Beefsteaks and San Francisco is not a match made in heaven).

However, by removing those flowers once they are in a situation where they can be pollinated successfully, what is accomplished by removing those flowers? FEWER TOMATOES! And, unless you are trying to stop production, it would be counterproductive to your ultimate goal: shoving that beautiful red orb into the face of your non-gardening neighbor on the Fourth of July, singing, “Nyah, nyah, nyah!”

Wow, where did this fallacy begin? One caller to the radio show offered a clue when he prefaced that question with, “Last night, the local TV Weatherman said…”

Bad move, taking gardening advice from a person who guesses for a living.

Still, that piece of  poor advice must have some historic legs to it. And sure enough, there are many people at Internet gardening forums who are passing on this wrong-headed notion. And as far as I can tell, it’s the result of one gardener reading a piece of university-based research on tomato pruning, and mangling the retelling of that research.

For example, Texas A and M University offers these tips for tomatoes:

"Greenhouse/Hydroponic Tomato Culture (winter)
Single crop rotation-seeded in July or by early August.  Transplants set in greenhouse within 10 to 30 days of seeding.  Harvest begins from 85 to 100 days following date of seeding and continues into June or early July.  Cessation of pollination is six weeks before  termination of the crop.  Growing point is allowed to grow for at least five to seven leaves  above last fruit truss to help prevent sunburned fruit.  Remove flower buds above last fruit  truss to assure no additional fruit set."

Gardener A reads this, and then retells the story to Gardener B, omitting the fact that these were WINTER tomatoes grown in a GREENHOUSE, HYDROPONICALLY. Gardener B then tells Gardener C: “Pruning tomato flower buds is recommended by Texas A and M.” Gardener C then goes online and writes: “Remove flower buds on tomato plants to increase the number of tomatoes.”

Or something like that. And another digital gardening virus is born.

When and how should you prune tomatoes?
Very little, only when necessary, to keep the plants within bounds. If you grow your tomatoes in cages (recommended), you would only need to remove those branches that escape and are threatening to wrap itself around a nearby pepper plant.

If you grow your tomatoes using stakes for support, you may need to do some pruning, according to the University of California:

“Staked tomato plants usually require pruning to a few main stems. At the junction of each leaf and the first main stem, a new shoot will develop. Choose one to three of these shoots, normally at the first and second leaf-stem junction, for the additional main stems. Once a week, pinch off most of the other shoots, called suckers, with your fingers, to keep the plants from becoming to large for their support.”

And, it should be pointed out, that if you follow those pruning guidelines for staked tomatoes, you are sacrificing about 25% of your eventual tomato crop. Yet another good argument to cage, not stake your tomatoes. Cages can be made from sheets or rolls of concrete reinforcement wire with a six inch mesh (the six inch opening makes it easier to reach those tomatoes). The sheets are usually 42” by 84”. Snip off the vertical bars on one of the 42” ends, bend it into a circle, attach the horizontal arms from the snipped end around the other  42” side and you have a tomato cage that’s 42” tall and about 27” in diameter. And it will last for decades. Want a bigger cage? Turn the sheet sideways, snip one of the long ends, bend it into a circle, and you have a cage that’s 84 inches tall and about a foot wide. But I would only do that if I am trying to grow tomatoes as per the instructions of a square foot garden.

Cornell University says hacking back your tomato plants is not necessary:

“…you can grow perfectly fine fruit without pruning your plants. But if you want to prune, here are a few guidelines. For determinate types, there is no need to prune at all. For indeterminate types, allow one, two, or three suckers to grow from the base of the plant. Each of these will become a main stem with lots of flowers and fruit. Prune off all the others suckers and provide the plants with strong support. Research has shown that the best time to remove suckers is when they are about 3 to 4 inches long. For the semi-determinate types, limit your pruning. When the plant is 8 - 10 inches high, look carefully and observe the first flower cluster on the stem. Remove all the suckers below the flower cluster except for the one immediately below the cluster. You may have to go back and give these a second pruning 7 to 10 days later. Remove no more than that or you run the risk of pruning too much. The amount of pruning among these varieties to produce optimum yields varies. Some varieties would do better if you left 2 suckers below the flower cluster. Experiment and see which works best for the variety you are growing.”

The book, 
“Ortho’s All About Tomatoes”, puts in more succinctly, quoting the late Dr. Phillip Minges of Cornell: “Tomato yields per plant may be lowered by pruning. Removing the leaves or shoots does not conserve food for the crop, it tends to reduce the total food supply…use training methods that require little pruning.”

A final hint when searching for garden answers on the Internet. Be leery of advice from gardening forums, unless that advice is linked to a study or research that you can also access. When using a search engine, include the words to identify a prominent agricultural school where the advice is reviewed by multiple parties before publication: UC (University of California), WSU (Washington State), Cornell, TAMU (Texas and M), etc.
For example Googling the phrase “tomato worm UC” will lead you to the University of California Integrated Pest Management website first. If you were to just enter the words, “tomato worm”, well…good luck.

Now, if only I could figure out how to (on my Mac, using Firefox) move the images in Blogger to where I want them....