With a normal amount of rainfall this year, it is hard to imagine that summer Alabama weather will likely begin to get back to normal – hot and dry. The month of August is typically the second driest month on record, after October. This change can have a direct effect on lawns and gardens. Most plants had been spoiled with the abundance of water and not had to deal with the dry weather and heat stress until now. The change in weather patterns means they may get thirsty. The only chance for survival may be through supplemental irrigation.
Water is essential for a top-notch garden. Vegetables are made up of 80 to 95 percent water and because they contain so much water, their yield and quality suffer rapidly when subjected to a drought. Thus, for good yields and high quality, water is essential to the production of most vegetables. If water shortages occur early in the crops’ development, maturity may be delayed and yields reduced. If a moisture shortage occurs late in the growing season, quality is often reduced, even though total yields may not be affected.
Most vegetables are rather shallow-rooted. Even short periods of two to three days of moisture stress can damage yields. Irrigation is likely to increase the size and weight of individual fruit and to prevent defects – such as toughness, strong flavor, poor tip-fill and pod-fill, cracking, blossom-end rot and misshapen fruit. On the other hand, too much moisture can have adverse affects on the plant incluidng slow plant growth, yellowing of the leaves, fungal diseases, smaller fruit and rotting of fruit.
Most homeowners don’t irrigate their vegetable gardens but often wait too long to begin irrigation, assuming it may rain the next day. This often results in severe stress. Drought and heat stress can begin in as little as three days after a 1-inch rain or irrigation; thus, frequent watering is necessary to maximize yields.
Up to 1-1/2 inches of water is needed each week during hot periods to maintain vegetable plants. During long dry periods, soak the garden thoroughly once a week; don’t just sprinkle daily. Light, frequent irrigation helps only during seed germination. Overhead irrigation, especially late in the afternoon, is likely to spread certain diseases. If using overhead irrigation, do it earlier in the day so plants can dry before night. Lastly, remember to always place mulch around vegetable plants, as it will help hold the moisture in the soil and keep the plants cooler.
Lawns are a major investment, and turfgrasses, like all plants, require water for growth and survival. There is an even bigger investment to replace them. This means there is a time to drag out the hoses and irrigation sprinklers. In my opinion, a higher water bill each month is much better in the long run versus the headache and expense of having to replace the lawn.
The most efficient way to irrigate or water a lawn is to apply water only when the lawn starts to show signs of drought stress from the lack of moisture. There are several ways to help determine when the time has come.
The visual condition of the turfgrass blades can be used to evaluate drought stress. The first sign of drought stress is the color of the turfgrass, as it turns from green to a bluish-gray to even a white cast. Turfgrass blades respond to drought stress by folding, rolling and/or wilting. Centipedegrass lawns, in particular, are not drought tolerant and can be the first to show signs of suffering.
Another indication is the footprints on the turfgrass. Walk across the lawn late in the afternoon and look back. If the steps have left any footprints, the lawn may need watering. When feet compress the leaf blades of the turfgrass, the low water levels in the plant tissues prevent the leaf blades from recovering or springing back up after being pushed down. If the footprints remain for an extended period of time, water the lawn to prevent the turfgrass from turning brown and becoming dormant.
Another means of evaluating drought stress on a lawn is the screwdriver test. To do this, push a screwdriver down through the stressed lawn patches and into the soil. If the soil is very dry, it will be difficult to push the screwdriver down into the ground. Use this test to confirm the results of the other visual indicators above to help determine when a lawn should be watered.
If a lawn exhibits the visual symptoms of drought stress, apply about 1/2 to 1 inch of water, which will moisten the soil to a depth of 4 to 6 inches, depending on the soil type and degree of soil compaction. Then, after watering, use the screwdriver test to determine the depth of water penetration. This will prove valuable for the future in determining how much water should be applied.
Unless the lawn has received a significant amount of rain lately, as a general rule, apply about 1 inch of water per week. Increase the amount to 1-1/2 inches during severe dry periods. And it is also best to divide the irrigation time into two 1/2-inch applications per week. When watering, avoid applying water to the point of runoff. Allow the water to soak into the lawn and soil. If needed, apply less water and allow it to soak in before continuing with the watering process.
Once the lawn has been watered, do not water again until similar drought stress symptoms are observed. Irrigating every day is not recommended. Never water a lawn every day, except during the establishment phase or renovation. Frequent watering only encourages shallow rooting of the turfgrass plants, making the lawn less drought-tolerant.
Automated irrigation systems and timers are convenient but can have flaws. Make sure the system is working properly and is applying the correct amount of water of 1 inch per week. Irrigation systems should be set or manually turned on twice per week in the early morning hours to meet this need; however, if significant rainfall has been received for the week, turn off those automated timed irrigation systems, so water is not wasted.
The best time of the day to irrigate or water is early in the morning because it minimizes the potential for water loss through evaporation. In addition, watering in the morning will not create the environmental conditions that promote the occurrence of diseases.
For additional help with home and garden information, contact the local county Extension office or visit aces.edu.
~ Shane Harris is the Tallapoosa County Extension Coordinator for the Alabama Cooperative Extension.