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RECOVERING FROM A HARD FREEZE – BOTH GARDENER AND PLANTS

Damage to Calamondin Orange and Variegated Oleander from 20 degrees in Austin.

Leaves will drop and plants will be pruned back to live wood for spring recovery.

To us gardeners in central Texas, despair generally follows a hard freeze when the first effects on our beloved plants are noted, but deeper despair follows a week or two later when the real damage is finally revealed. Some effects may take a month or more to become noticeable. Before despair leads to depression, let’s look at the bright side.

Those dead looking plants most likely aren’t really dead – they’re just playing “possum” and waiting for spring conditions to revive. It’s their natural defense mechanism to shut down under such conditions.

   With shrubs, use the fingernail test – scratch progressively downward until dead brown tissue becomes green live tissue. Then they can be pruned back to just above that point for regeneration. Although we are advised not to prune back more than one third of a shrub at any time, hard pruning beyond that level may be required to remove dead wood. With perennials, cutting back an inch or two from ground level will help regenerate them in spring. Root freezing is their worst fate, not death of foliage. In the case of Yuccas, Agaves, they most likely will send up pups in spring from the surviving base if top foliage dies, unless the entire plant froze, roots and all from soil being too moist.

The deep freeze kills many of the harmful insects that invade and harm our gardens so it’s natures way of keeping everything in balance. Dead growth should be removed however to prevent the introduction of disease organisms in decaying matter.

The occasional loss of some of our plants provides the opportunity to rethink our garden design and content. It is good to try different plants in different growing seasons. The garden becomes a research laboratory of sorts. Perhaps the loss of some plants has provided some additional space to do just that. Perhaps there are lessons learned from which we benefit. For example, my large 18”x24”ceramic pot that contained hardy water lilies didn’t survive whereas the lilies did! I forgot about the expansion of water as it becomes ice – duh!  So, my lesson learned is to use a galvanized metal container for this water lily garden in the future.

It also pays to keep records of plant performance under different stressful conditions, a journal or sort to refer to if those conditions occur again. Note micro-environments that provided just enough protection to help a plant survive beyond it’s normal expectation. Also note those plants that were totally unaffected by the sub-20 degree cold and use these as base plants (the bones) for your garden.

Often, conditions other than the cold cause death to plants. I had a native Claret Cup Cactus croak (say that fast 10 times) that is supposed to be hardy to 20 but cacti can only handle lower temps when the ground is dry – so I knew what did it in and will try to provide a dryer growing condition for similar plants. Let’s face it. We don’t get a lot of rain per year in our area, but when it rains, it rains, and often at the worst possible time – just before a freeze which can be a much deadlier combination that just the freezing temperature.

The most agonizing thing for a gardener is the long wait to see if a plant that has died back to the ground will emerge as a healthy plant in spring. This doesn’t always happen. Often disease organisms attack a weakened plant when in dormancy. If a plant doesn’t emerge at an expected time in spring, it is best to dig and examine roots for any signs of life, buds, live roots, etc. Any dead portions should be trimmed off before replanting. Do not fertilize any plants in spring until healthy shoots emerge and begin to mature, as without leaves for photosynthesis, chemical fertilizers can become toxic to the plant. If shrubs are just tip burned from a freeze, don’t trim back until spring as that would just encourage new vulnerable growth to emerge prematurely.

Rather than seeing the damage a hard freeze brings to your ornamental garden, look at the bright side. If nothing else, you can look forward to seeing the resurrection of life anew in spring as you stroll through your yard. Also see the opportunity to improve your garden from the previous year based on what you have learned from this winter. Don’t jump the gun though but wait for the right time to begin that renewal. You can cultivate soil, build up and enrich your beds, do any additional hardscaping you want to do to your garden infrastructure, research new planting possibilities for the coming year while waiting for any danger of frost and freeze to pass, generally around April 1st in central Texas. This way, you will be raring and prepared to jump into another wonderful year of gardening pleasure.

So don't despair.  It is psychologically tough for us as gardeners to see what old man winter does to our gardens, but it could be worse - you could be the poor plant out there  trying to survive it! 

FROM SCORCHING HEAT TO DEEP FREEZE

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!