It is that time of year when we play chicken with Mother Nature. Will it really get that cold? Am I in a little pocket that’s warmer/colder/somehow different than the forecast? Some of us are in perpetual denial, while the rest (like me) run around like Henny Penny thinking the sky is falling.
Depending on the source you check, the average first frost here in Austin is said to be anywhere between November 28 and December 5. We didn't follow the norm this year - with one of the earliest freezes for some areas last week. Regardless of when winter arrives, there are many things you can do protect tender plants from frosts or freezes.
First, water moderately before the freeze. Water loses its heat more slowly than air throughout the night. Combined with covering plants or even a heat source, watering can help make a real difference by a few critical degrees.
Sheets, blankets and heavyweight row cover can all help protect plants from a freeze. But it’s important to note that it’s not the cover that keeps the plant warm, it’s the radiant heat coming up from the ground that is held in by the cover. Drape the cover all the way down to the ground and secure it like a tent with rocks, bricks or my favorite – canned vegetables (lighter than rocks, easier to find in a pinch, and they don’t mess up your sheets and blankets).
Do not, however, drape something over the top of the plant and then tie it around the trunk like a giant lollipop. This is pointless, because you are actually keeping the heat away from the plant. If you have plants that can’t withstand the weight of a blanket or sheet, you can plan ahead and use tomato cages, large boxes or PVC hoops or frames – really, anything to hold up the cover.
For particularly tender plants or a really cold night, you can also add a droplight or the large-bulb Christmas lights under the cover to create some additional heat. Be careful not to let the bulb touch either plant or cover.
When temperatures rise above freezing – remove covers the next day to allow the plants to absorb the next day’s heat and recover as necessary.
Protecting container plants is a little trickier. Their roots are much less insulated than plants in the ground and will get much colder. To protect them, you can group them against your house and use the same techniques as you would for in-ground plants. Even the littlest radiant heat from the house can help make a difference on a cold night.
Having spent years putting big pots of plants in the garage, this is also a great way to overwinter them, with a few conditions. Remember, plants need light, and overhead light won’t cut it. If you don’t have windows in your garage, make sure you open the garage door to let in sunlight and fresh air when temperatures allow. In the garage, some plants will go dormant for the winter reserving their energy in their roots for the next spring. Water them sparingly and let them rest for the winter. Once indoors, these plants require less water since there is no wind, and winter
daylight hours are shorter and lighting levels lower. When their leaves drop, don’t worry and don’t fertilize them to try to push them into growth while they are inside.
So, plan now – collect your sheets and blankets, find some tomato cages, lights and canned goods and you’ll be ready to go when a surprise weather forecast sets you scurrying in the dark at 6 p.m.