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Garden Tips

Plant Drought Survival
By: Bob Beyer, Travis County Master Gardener

While we are hibernating in our air conditioned, climate controlled home environment when daily temperatures exceed 100 and one of our worst droughts is in progress, can we have a little sympathy for our outdoor plants who don't have such a luxury?  A gardener's biggest stress is worrying about them when the forces of nature are being so cruel.  I mean, we love our plants and do all we can to care for them, especially in their times of trial.  So, what can we really do other than worry?  First identify what their stresses are so we can act accordingly.  A plant's greatest stresses during drought and heat is light intensity and excessive transpiration. 

Especially between June 1 and July 31, near the summer equinox,  the longer daylight periods provide more intense light than most plants are accustomed to during the year causing some foliage to wither, die, or pale in color.  Plants affected in this way may need some temporary protection – container plants moved to a shadier area or perhaps a sun screening net placed over them to reduce the direct sunlight hitting them.  Remember that full sun in central Texas is much more intense than full sun in more northern regions of the country.  The light limestone soils in Hill Country also reflect light adding to the intensity.

Transpiration of moisture from ground through the plant into the air is accelerated by low humidity, high temperatures (heat rises), and wind.  Plants may show foliar wilting during the heat of the day but recover during the cooler periods of dusk through dawn, but once soil moisture runs out, they may have a real problem.  Transpiration also provides cooling for the plant as water is drawn through their system, in addition to being a vital element in growth, photosynthesis, and turgidity.  So a little help for many of your plants is needed unless the plant has built in adaptations to prolonged heat and drought, Cacti, succulents, and many desert shrubs which minimize foliage size, have pubescent foliage, waxy outer layers to reduce transpiration, or specialized cells for water retention Many desert plants put themselves into dormancy during summer as well as winter.  These plants need to be kept dry and excessive watering can be damaging to them in that state.

Knowing your individual plants, where they are native and the conditions they are adaptable to is essential to caring for them during tough times.  Placement of plants with similar care needs together makes it easier to maintain them well.   At the same time, we as gardeners must minimize our use of water during restriction periods.   So some tips on watering to achieve this follow:

  1. Water less frequently but deeply and thoroughly.  Hand water around the leaf line of the plant to concentrate watering where the roots are.  Water once, then again after the first watering has had a chance to soften the soil and penetrate.  The deeper the watering, the deeper the roots will grow to places where water retention is the greatest – at depth. Sometimes it helps to use a stick to poke a holes around the plant before watering which will allow water to penetrate deeper.  
  2. Water before 9 AM or after 6 PM to minimize evaporation.  Surface sprinklers are not effective due to evaporation.  Soaker hoses work well, but hand watering allows you an opportunity to observe the general health of your plants regularly to make sure your watering plan is effective.  It is possible to kill a plant by overwatering in summer as too much water will choke out soil air space needed for good root growth and oxygen uptake.  Cacti and succulents especially need soil that dries out thoroughly between waterings. 
  3. Don't prune or fertilize, during stressful periods.  The last thing you want to do is encourage the plant to produce new growth when it is struggling just to survive.  Wilting and cessation of growth are survival mechanisms and natural ways for plants to reduce stress during drought and heat.  Take a break from the summer heat just like the plants do.
  4. Don't plant or transplant during stressful periods.  Plants take a period of up to a year to establish themselves and adapt to a new environment, but once established, will hold their own.  Spring and Fall are the best times to plant and transplant depending on the plant.  Drought tolerant plants will not survive until good root systems are established so extra watering and care during the first year of a plant's life is necessary. 
  5. Perhaps the best solution of all is to plant native, drought resistant and adaptive plants to the greatest extent possible in your ornamental gardens.   Good plant choices – the ounce of prevention beats a pound of cure approach – reduces stress on the gardener as well as the plants having to endure.  Do your homework and research the best plant selections for the environment where they will live.  Remember your yard has micro-environments which affect plant choice. The trick is to find the right plant for the right spot.  By careful selection of plants, you will not only reduce your stress and that of the plant, but save money by not having to replace plants that don't make it.  Help abounds in Austin through many organizations, publications, and individuals such as Master Gardeners, the City of Austin 's Grow Green program, the LBJ Wildflower Center, just to name a few.  It always helps to get second opinions to see if the sources you consult are in agreement.  

Even the most drought tolerant plants may need a little hands-on help during our prolonged drought and severe heat, while we need to conserve valuable water resources at the same time. Some effective ways  for gardeners to recycle and save water is to keep a bucket near the sink or any water source and fill it while waiting for the hot water to emerge or waste water and use it to water some plants, and/or draw water from your rain barrels (you do have one or more I hope) for use on potted plants. Try to minimize water that will go down the drain or down a storm sewer and redirect it to help your landscape.  Only water in accordance with your local water restrictions. Hand water as much as possible.  I even wash my car on the lawn so run off water benefits the lawn!

Often the best approach is to do just enough to keep our plants alive, even though they may not aesthetically look good, knowing that during better times, they will recover and once again thrive -  and oh yes, KEEP PRAYING FOR RAIN!  

 
©Zilker Botanical Garden,
Austin Area Garden Council
512.477.8672
info@zilkergarden.org