By Tom Barrett
Drought! It’s do or die time for your landscape. Landscapes are one of the most valuable components of a property. Not only do landscapes make our physical environment more attractive, they can be as transforming as a fresh coat of paint on a house. More importantly, landscapes are critical to remediating our environment. Trees, shrubs, perennial, annuals and turfgrass all help to clean our air and create the oxygen we need to breathe. Preserving a landscape during a severe drought can be one of the most challenging crisis in the landscape industry. Recovering from a severe drought is frustrating to say the least. Implementing a comprehensive strategy to restore the balance of the landscape is vital to the soil and the industry.
The soil is the lifeblood of the landscape. Soil, when properly maintained, encourages deep roots. During a drought, plant roots, the storehouse of plant carbohydrates, are the survival mechanism of the plant. Too often good soil management practices are completely overlooked in landscape management. We pay too much attention to the leaves of a plant and not enough attention to what is going on below. The foundation of any living system is in the roots.
Preparation for a drought starts with good cultural practices in the soil. Good soil aeration combined with proper fertilization encourages deep rooting. Plants will have greater success in withstanding the devastating effects of a drought if their root system has been cultivated to grow a deeper, more extensive root system.
Good soil preparation is not reserved for new landscape installations. Soil cultural practices, like aeration can be performed at anytime. Spring time is best because for most plant material spring is when a plant’s root development is most active.
Soil fertility and salinity or the amount of salt found in the soil, are important. In the spring, it is important to get a soil sample and have it tested at a soil lab. Once results have been analyzed, correcting any nutrient deficiency is the first step.
For turfgrass a spring aeration is essential to encourage deep rooted turf. Ideally, turfgrass should have rooting depths of 6 to 12 inches. For trees and shrubs, drilling several holes 2 to 4 inches in diameter, 24 to 36 inches deep around the base of the plant will encourage deeper water penetration and deeper rooting.
Filling the holes with compost will encourage healthy soil mirco-biological activity.
Mow turfgrass higher and be careful about applying too much nitrogen fertilizer. Nitrogen encourages top-growth of grasses at the expense of developing a strong root system.
Deep infrequent irrigation cycles also encourage deeper rooting. Mulch, properly placed around trees and shrubs also helps to preserve soil moisture.
When a drought happens it is important to have a plan and priority. Trees come first. Trees are expensive to replace. The loss of a the shade from a tree will increase the evaporative water losses in the surrounding area.
After establishing a healthy root system, pay close attention to the leaves of all plants. The leaves are the best indicator of a plant’s water need. When turfgrass starts to turn bluish-green it is time to add water. The wilt symptoms of many trees and shrubs will exhibit leaf folding. Sometimes the leaf folding will also display a slight change in color.
Do not fertilize during a drought. All fertilizers contain salts that will rob the plants of any moisture in the soil. Avoid fertilizing the plants until they have recovered. Fertilizing after a severe drought will usually increase leaf and stem growth at the expense of root development.
Do not prune during or immediately following a drought.
Apply water slowly and deeply to the soil. Reduce evaporative water losses by watering after the sun goes down.
Most importantly, physically check the moisture level of the soil. The soil may look dry on the surface, however with a soil probe or a six inch screwdriver stuck into the ground you can accurately determine how deep and how dry the soil may be.
Recovery – Water, Water, Water
Recovering trees, shrubs, and turfgrass after an extended drought is different for each type of plant. Water, water, water is the key to successful recovery, however the proper watering cycle for each type of plant is different. Monitoring the soil water level during the process will help insure a more successful recovery.
Trees require deep infrequent watering. Gently soaking the soil to a depth of 36 to 48 inches is important. Allow the soil to dry out before watering again. It is critical to avoid light frequent waterings that will only penetrate the soil to a depth of a few inches. This will result in shallow roots.
For shrubs watering to a depth of 18 to 24 inches is important. Allow the soil to dry out before watering again.
Recovering turfgrass is the most demanding watering regimen. Initially, light frequent waterings are important. Continuously monitor the soil moisture level with a probe or a screwdriver. Once the turf has started to recover a deeper less frequent watering schedule can be resumed.
After severe water stress all plants types slow in growth because their metabolism has been significantly reduced for survival. The water initially applied will be slowly absorbed by the plant. Water absorption by the plant will be dramatically reduced until the plant starts to become healthy again. Once the plant material starts to regain its health, it will rapidly use water.
Understanding how a plant recovers from severe water stress is vital to recovery. Nutritional and watering needs vary widely from plant to plant and from location to location. Careful soil monitoring is key to returning plants to a healthy balance following a severe drought.
In nature drought is natural part of the environment. Most native and well established plants can withstand a considerable period of time without rain. Maintaining and protecting landscapes during a drought is worth the effort when compared to the cost and time required to reestablish a landscape. The best defense against drought is a strong offense. That offense starts with a solid plan, good preparation, and the desire to work with nature to restore the balance she intended.
Note: This article originally appeared in Landscape Management