We are in the midst of a serious prolonged draught. As the temperatures increase any stress factor that affects your lawn and landscape will become more evident. If you take the time and make the investment now to reduce these stress factors, your landscape will profit all year long.
Here are 14 important suggestions to reduce heat and drought stress.
1. Set your mower to a high setting so the lawn has nice long blades. This will help shade the soil and moderate the temperature. More importantly it will encourage a deeper root system. Roots and shoots are always kept in equilibrium and grass mowed too short will have an insufficient root system for finding precious moisture. St. Augustine varieties should be allowed to reach 3.5-4 inches tall during the draught.
2. Only mow with sharp blades. To reduce leaf stress the blades must be cut, not ripped. If the blades are not sharp enough you will notice a white appearance across the top of the lawn. Close inspection will reveal irregular ragged edges instead of nice clean cut. Ragged edges will allow the leaf blades to dry out faster.
3. Irrigate deeply on your watering days. In this drought your irrigation system is only able to keep your lawn alive, it will not promote much, if any, new growth. The soil moisture level is just too low and even a good irrigation system can not overcome the deficit in the time your county may give you to water. You need to apply at lease 3/4 of an inch of water per square foot. The best way to tell if you are getting enough water is to purchase about 10 collection cups from your irrigation service or supply company. Space these around to cover the entire area of each irrigation zone, one zone at a time, run the system normally, and check how much water was applied on average across that zone. You can use this information to increase or decrease the time that zone is on. You must apply this amount of water during each irrigation cycle, not accumulated over the days you are allowed to water.
4. Make irrigation system repairs. Using the information you learned above adjust heads or add new heads to provide uniform coverage over each irrigation zone. Dry spots will show up quickly now. Each sprinkler should overlap all the way to the adjoining sprinkler. A little overlap, or even 50% overlap will not provide enough water this time of year. Good coverage will mean you can run the system for shorter periods of time since you are not over watering some areas to cover the dry spots.
5. Do not run your sprinklers in the heat of the day. You will lose too much water to evaporation and wind drift. Although it increases the risk of leaf disease when foliage is allowed to remain wet overnight, it is better to water during the night if that is your only option. The best hours for irrigation are 4 AM to 9 AM. Leaves that are wet for more than 4 hours provide an excellent environment for fungal spore germination which allows for an increase in disease establishment and spread.
6. Keep your lawn and landscape well fertilized without using too much Nitrogen. Rock powders or fertilizers containing the mineral elements Calcium, Potassium, Copper, Iron, Manganese, Boron, and Molybdenum will help roots grow deeper and find elusive water. Do not use more than 10% nitrogen in a draught.
7. Keep lawn traffic to a minimum. Playing soccer on a droughty lawn will cause die back.
8. Use liquid nutrients that are absorbed through foliage to give lawns and landscape an extra boost. While the soil is dry plants will not be able to acquire all the nutrients they need. We suggest monthly foliar spray applications in the summer months. 9. Make sure all landscape beds are mulched. Mulch will regulate the soil temperature and prevent extreme heat. It encourages beneficial soil microbes which will quickly die in bare soil. Mulch in beds and around trees should be 3" deep for the best water and weed control. Use a coarse mulch that will allow water to quickly penetrate instead of running off. Fine mulches or those with a high percentage of thin wood strips or sawdust will form an impenetrable barrier to water and even exclude air allowing CO2 to build up in the soil. Pine bark mulch is the best mulch for air and water penetration. Shredded hard wood is the most damaging. Coarse Cypress mulch of any color works pretty well but tends to solidify into a nonporous mat over time.
10. Consider drought tolerant plants and ground covers. Your only alternative to St. Augustine lawns suffering from draught in times of water restrictions may be hardy ground covers, mulch, or xeroscaping. Jasmine ground cover, Trachylospermum asiaticum, is a very drought tolerant ground cover but it will require regular watering to get established after planting. Liriope varieties also do well. Ivy works well but is very slow to get established and you will probably get tired of pulling weeds before it ever fills in! African Iris beds make a beautiful mass planting and are very draught resistant. Keep the well fertilized or they will be attacked by scale insects. Expanding beds and adding a minimum number of drought resistant shrubs can be an attractive alternative to large lawns. You can also add beds and ground cover allowing the lawn to frame your landscape instead of being the dominate feature.
11. Keep your shrubs pruned to reduce leaf surface area. You don't have to shear them, in fact frequent shearing will expose open wounds that are subject to water loss, disease and insect infestations. Just keep long whips cut back and remove all suckers that may arise.
12. Consider planting shade trees in areas where the lawn is in full sun and drying out is a problem. Too many trees will make growing grass impossible but a few well placed Live Oaks can reduce your water needs (an AC bill) considerable. As they grow just prune off the lower branches so there is enough light for good turf growth.
13. Top dressing your lawn with a high quality LIVING compost will add much needed organic matter to lawns and landscape beds which will help hold moisture and reduce insect pressure. Bag compost products that have been sterilized will still add organic matter but provide no beneficial soil microbes which help roots resist chinch bugs and acquire water and nutrients. Do not add more than 1" at a time. In most cases a light spreading of 1/2" is sufficient and can be done every year until your soil test shows 3-5% organic content in the soil.
14. There are good spray adjuvants, usually long chain polymers, that help the soil hold and retain water. These should be added to your monthly spray program. You can also add granular polymers that absorb and slowly release water to your soil. This is a more expensive alternative.
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