From a record setting, hottest summer in recorded history, drought, and now to the coldest December and winter to date in central Texas – what conditions could better test the endurance, hardiness, and tolerance of plants to extremes than this? The garden this past year has been somewhat of a laboratory, teaching gardeners some important lessons about plant choices and the benefit of using native and adaptive plants and also how to deal with extreme climate contingencies.
So, let’s address the deep freeze aspect. Most gardeners like to push the limits of plant tolerances in order to grow a wider variety of plants. I am definitely in that category. If this is you too, you need to develop a strategy for dealing with extreme contingencies in our climate. Here are some suggestions – learned through actual experience and from others.
1. Know your plants!! This is vital information that will help you get them through tough times. Studying about each plant in your garden through books, articles, and from trusted sources on the internet will give you the knowledge to know how and when to protect your plants from harmful conditions such as below freezing air and ground temperatures, frost and icing.
2. Don’t grow more plants requiring special care and protection than you can reasonably accommodate. That will only result in discouraging plant losses each year.
3. Plants placed in garages during freezes will be subjected to very low lighting (if any at all), and the possibility of subfreezing temperatures even when not outside. Never water plants under such conditions as the lower the light levels, the lower the water requirements, and certainly, you don’t want roots to freeze in containers . This could also lead to disease problems. Use lamps that generate heat to provide a micro-warm environment around plants in your garage.
4. Outdoor plants that are subject to freeze damage should be covered with thick blankets or coverings, never plastic touching the foliage. Coverings that are subject to rain prior to freezing are also not recommended. You can put plastic over blankets in such conditions. Always weigh coverings down so they won’t blow off during a freeze period. If you can’t cover the whole plant, protect the core area. Damaged foliage can always be trimmed off and regenerated.
5. Don’t water in-situ plants subject to freeze damage prior to arrival of a freeze condition. If the ground freezes the moist soil, it could kill your roots and plant entirely. If a plant absorbs water prior to freeze, the water expands within the plant and plant cells literally explode. Most hardy plants that don’t die back have hardwood and bark as thermal protection.
6. Never prune plants during periods subject to freezing. That will encourage new growth which will lead to further dieback when the next freeze hits.
7. Try using large 10 gal or larger nursery containers turned upside down as covers for smaller plants or for larger plants pruned back to 12” or less. Also mulch heavily around the base of plants that dieback to protect the ground from freezing around the roots. For example, I know my Duranta shrubs will die back in winter so I cut them back in early winter to 12” and use this technique to protect the base of the plant which will grow back in spring if roots are prevented from freezing.
8. Freeze damage often not noticed immediately and often takes a week or so to become evident. Monitor your garden daily during stressful conditions.
9. When pruning damaged or dead branches, never cut back to live tissue but cut to just above the live area. This seals the plant from further dieback or exposure. To find where live tissue begins, just use your fingernail to scrape the bark and you can find where the live green and dead brown tissue meet.
10. Consider the presence of micro-climate conditions. For example, ground under the heavy canopy of a live oak tree would be much less likely to freeze. Any area with a canopy or near a building which absorbs heat during the day, or is protected from northerly wind exposure can be a few degrees warmer during a freeze.
11. Remember that outdoor potted plants are at much higher risk of being killed in sub-freezing conditions due to above ground exposure of soil and roots to freezing temperatures. Pots with wet or moist soil can crack easily during hard freezes due to the expansion of water as it freezes, so protect your clay and ceramic pots as well as plants.
12. If you can divide or take an offshoot of a plant that may not make it through winter on it’s own, and keep the smaller piece protected in case you lose it outdoors, this is a form of plant insurance to make sure you don’t totally lose a favorite plant that might be hard to replace.
Finally, Never anticipate what weather conditions will be in the future, but monitor forecasts throughout the winter period. Weather is very unpredictable beyond a week in advance, so you must be prepared to deal with any climate conditions on short notice that could kill or damage your plants. “Be Prepared” as the Boy Scouts would say.
I am fortunate to have a hobby greenhouse, be it small, to provide protection for tropical and plants that are tender to freeze and frost. If you are really into gardening and find it affordable, there is no better tool for dealing with extreme conditions and providing good growing conditions for plants during the 3 months of winter we experience in central Texas than to have a greenhouse. Ours is only about 80 sq. ft. and can be heated with one space heater, a second one on standby for extremes, to maintain 50 degrees or higher. The purpose is to not get plants through winter as though nothing has affected them, but to just get them through alive and healthy so they can regain their vigor in spring.
Most important, keep your spirits up, don’t let winter damage to your plants discourage or dishearten you but just accept that as a gardening reality that can’t be avoided. Spring is coming – things go uphill from the depths of winter – ever so slowly but in the right direction as we look forward to our spring garden and plan for another successful gardening year. This is a great time for the gardener to be learning, studying, planning, and DREAMING!