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Garden

Warming up to cold blessings

With proper preparation, your plants will survive chilly spells. Mosquitoes and weeds won't.

By JOHN A. STARNES JR., Special to the Times
Published January 27, 2007

Frosts and freezes in Central Florida can be mixed blessings. On the down side, they endanger tropicals and tender crops like tomatoes and strawberries. On the up side, they wipe out lingering mosquitoes, summer garden pests and weeds. But that sends us back into the garden to do some overdue pruning.

More work for us, however, means rest for some plants. Cold weather brings a welcome dormancy to roses and stone fruits, such as nectarines and plums. And the koi and goldfish in our ponds enjoy the cooldown after another hot summer.

Let's review some easy, effective ways to protect frost-vulnerable plants. Clip and save this story!

- A time-honored first choice is to give your garden a deep soaking in the daytime before the freeze arrives that night. Well-watered plants resist freeze damage better, and thoroughly dampened soil holds more latent heat. Citrus and strawberry growers take this one step further and run sprinklers at night to coat their crops with ice as insulation against temperatures lower than 32 degrees.

- A second easy measure, just before sundown on freeze night, is to cover all your tropicals with sheets and blankets to trap the day's warmth. Don't use plastic; if it touches the plants, it conducts the cold directly to them. If you want to use plastic, build a frame out of lumber and tack the plastic to it. Use bricks and stones to hold the edges down, onto the soil, to keep cold air from seeping in.

- A variation on this theme is to invert plastic trash cans, 5-gallon plastic buckets, or cardboard boxes over plants before sundown to trap the heat released from the soil at night. If it's windy, a brick or stone placed atop them will hold them in place.

- Putting a heat source beneath these covers will do wonders to get tropicals through even a hard freeze like those of 1977, '83 and '89. A few gallon milk or water jugs filled with HOT tap water, tucked beneath a cover just before you hit the sack, can make all the difference in whether that begonia survives.

Some gardeners use strands of big Christmas lights (not the little twinklers) or a table lamp with a 100-watt bulb on an extension cord, or water bed heating pads.

Don't rig up anything that will be a fire hazard, i.e., light bulbs too close to fabric or open flames near sheets or blankets. Your garden and your house - and you - may be at risk.

- How to protect trees and other plants too big to cover? Again, copy the wise citrus farmer. A box fan on an extension cord aimed up into a citrus or papaya or banana on one of those perfectly still, cold nights will keep the air moving, and the electric motor releases some waste heat.

- Not the most energy-efficient solution, but here is another possibility: a heated pool or hot tub will warm the air nearby, providing steamy warmth for potted plants you range in its vicinity.

- Aim an infrared spot lamp up into the plant to warm the stems and leaves directly while the bulb heats the air rising past it.

With safety in mind, use your imagination in your garden to generate and trap heat and ward off cold.

Fast Facts:

Warm 'em up

Here are more tips to protect your plants when temperatures drop:

- Don't leave coverings (sheets, boxes) on longer than two or three days, even if you have to take the coverings off during the day and replace them at night. Plants need sun to photosynthesize and will start to yellow and fade if they're deprived for any length of time.

- In case of a light frost, hose the leaves of tender plants after the temperature rises above freezing but before the sun hits the foliage. The water removes the frost, which, if left in place, can act as a prism and magnify the sun, burning the plant.

- Once the danger of frost or freeze is past, check the plants for dryness. Plants can lose water vapor on a sunny day after a freeze. The wind that often accompanies brisk weather can also dry out plants. Water as needed.

- Delay severe pruning until new growth appears in the spring. Damaged foliage may recover on its own. Pruning encourages new growth, which is tender and vulnerable to damage from subsequent freezes.

Pinellas County Extension

[Last modified January 26, 2007, 11:05:26]