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With winter comes frost and freezing temperatures.
While manyplants are winter-hardy, others can be damaged by as little as one night of frost.
How Frost Damages Plants
When temperatures reach freezing or below, ice crystals grow within plant cells.
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The ice may rupture the plant’s cells, damaging parts of the plant or killing it.
Frost can also damage plant roots.
Frost and freeze events are different.
A frost is generally when the temperature reaches 36F, and the plants may be able to recover.
A freeze is 32F, and a hard freeze is 28F or lower.
Plants may not be able to recover from a freeze or hard freeze.
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Plants already in containers can be moved intact to asunroom or other suitable placein the home.
Like a blanket, mulch insulates the soil and keeps temperatures stable.
The besttime to apply mulchto the plants is in late fall.
A cold frame is a low structure built over and around the plant but not touching the plant.
You canbuild a DIY cold frameout of pressure-treated wood and plexiglass.
Greenhouses
You canuse a greenhouseto bring your plants safely through the winter, even during hard freezes.
Cloches
Cloches are transparent or translucent caps for your plants.
Traditionally, a cloche was a glass bell jar placed over each plant.
Just remember to remove the cloche the next morning after the frost danger is over.
That’s where row covers come in.
Elevated with hoops, the row cover runs the entire length of the plant row.
For a large-scale garden, it’s worthwhile investing in a set of row covers.
A full kit capable of covering 25 feet costs about $200.
Irrigation
Irrigate the soil around your frost-sensitive plants soon before a frost arrives.
Moist soil retains more heat than dry soil.
Deeply watered soil is dense and has sufficient mass to retain more heat than dry soil.
Container Wraps
Plant containers lack sufficient insulation to protect the roots during frost and freeze events.
In these cases, wrapping is the answer.
Zippered thermal plant container wraps cost $15 to $20 each.
A drawstring at the top lets you cinch the top of the wrap closer to the roots.
Frost cloths made from fabric-like synthetics are lightweight enough to be placed directly on top of the plants.
The cloths trap heat but allow sun and air to flow through.
Instead of frost cloths, it’s possible for you to use old sheets, blankets, or towels.
Since they’re heavier than frost cloths, they should be elevated from the plant.
Heat Banks
Place heat banks or heat retainers near the plants.
Your plants benefit from the dissipated heat.
Ideas for heat banks:
Plant Shelters
Add large sheltering structures or trees near the plants.
Just be careful not to block sunlight or airflow.
Phase out or reduce the number of plants easily damaged by frost.
This also helps reduce the number ofgardening tasks you should probably do before winter.
A plant exposed to frost can possibly be saved, depending on the extent of the damage.
An extended freeze, though, may rupture the plant’s cells and cause irreversible tissue damage.
Do not immediately cut off frost-damaged leaves.
Leave the damaged leaves on the plant at first.
Give the plant several days in warm weather so you’ve got the option to assess its health.
If the plant survives, even dead leaves can remain on the plant for insulation against future frosts.
Leaves may grow back after only a light frost.
However, wilted, droopy, or blackened leaves will not grow back.
But this doesn’t necessarily mean that the entire plant is dead.
Growth on other parts of the plant may be possible, even if certain parts are frost-damaged.
Frost and freezing temperatures and ways to protect plants.
How to Protect Plants from Frost and Freeze.
Iowa State University Extension and Outreach.
Using Row Covers in the Garden.
University of New Hampshire Extension.
The science of frost and frequently asked questions.
Government of Western Australia.
Winter Protection for Potted Trees and Shrubs.
University of Nebraska, Lincoln.
What to do with plants after a freeze.
Louisiana State University College of Agriculture.
Recognizing and Caring for Frost Damaged Plants.
Cold and Freeze Damage to Garden Plants.
Iowa State University Extension.
