Unexpected Freeze?
What can a gardener do when the weather is anything
but typical? Unexpected freezes can devastate landscapes and gardens. How do we protect our plants from freezing
and what is the best way to cover and keep plants from freezing? First lets look at how plants react to the cold.
At What Temperature Do Plants Freeze?
When cold weather is on its way, your first thought will be at what
temperature do plants freeze, or how cold is too cold?
There is no easy answer to this.
Different plants freeze and die at different temperatures. That is why
they are given a hardiness rating.
Some plants produce special hormones
that keep them from freezing, and these plants have a lower hardiness
rating (meaning they can survive colder weather) than plants who produce
less of this hormone.
That being said, there is also different definitions of survival. A
plant may lose all of its foliage during a freeze and the plant can
regrow from the stems or even the roots. So, while the leaves cannot
survive a certain temperature, other parts of the plant can.
How to Protect Plants from Freezing
If you are only expecting a light freeze, you may be able to protect
plants in a freeze simply by covering them with a sheet or a blanket.
This acts like insulation, keeping warm air from the ground around the
plant. The warmth may be enough to keep a plant from freezing during a
short cold snap.
For added protection when you protect plants in a freeze, place plastic over the sheets or blankets to help keep warmth in. Never cover a plant with just plastic, however, as the plastic will damage the plant. Make sure that a cloth barrier is between the plastic and the plant. Remove the sheets and blanket and plastic first thing in the morning after an overnight cold snap. If you do not do so, condensation can build up and freeze again under the covering, which will damage the plant.
When protecting plants in a longer or deeper freeze, you may
have no choice but to expect to sacrifice all or part of the plant hoping that the roots will survive. Start by heavily mulching the roots
of the plant with either wood mulch or hay. For added protection, you
can nestle gallon jugs of warm water into the mulch each night. This
will help drive off some of the cold that can kill the roots.
Insulation Barriers
If you have time before a freeze happens, create insulation
barriers around your plants to protect them from freezing.
Tie up the plant as neatly as possible. Drive stakes that are as tall as
the plant into the ground around the plant. Wrap the stakes in burlap
so that the plant appears to be fenced in. Stuff the inside of this
fence with hay or leaves. Again, you can place milk jugs of warm water
on the inside, at the base of this fence each night to help supplement
the heat. A string of Christmas lights (not the LED ones) wrapped around the plant can also
help add additional heat. As soon as the freeze passes, remove the
covering so that the plant can get the sunlight it needs.
Watering the soil (not the leaves or stems of the plants) will also help
the soil retain heat and can help the plant’s roots and lower branches
survive.
A Freeze Experiment
Shame on me for starting a garden too early! Next weekend temps are predicted to drop to the 20′s. In an attempt to try to save this newly planted garden by setting up an patio umbrella in the center of the garden and draping blankets and plastic to the ground. Hopefully, this will create an impromptu green house. Hanging a low wattage lighting string from the umbrella should help keep the heat in.
