Summer Lawn Care Tips: Mowing, Weeds And water

By David Chalmers

Summer is finally here after a difficult winter, a late spring warm-up and a good bit of spring rainfall in some areas of the state. The spring lawn care practices of fertilization and weed control should have already been done to set the lawn up for a good summer. Let’s consider the areas of summer mowing, weed control and watering and some of the “dos and don’ts” of each practice!
Mow a Little Bit Higher!

• Mowing Kentucky bluegrass and fescue lawns at a mowing height 3 inches or more helps the lawn cope with summer heat stress and shades the soil surface to reduce weed germination.
• Mow frequently enough to not remove any more than 1/3 the total leaf area in any single mowing. If your mower is set to a 3 inch cutting height try to mow before the lawn reaches 4 1/2 inches.
• If you are away from home for a while and the lawn is much higher than normal upon your return, it is best to adjust the cutting height a notch or two higher so as to not try and remove all the accumulated growth in one mowing. Cut it at the higher height for a week or two then drop the height a notch the next time you mow until you reach the desired summer cutting height.
• Frequent mowing also helps grass clippings to filter back into the lawn and recycle fertilizer nutrients.

Controlling Weeds in Established Lawns

Summer is not the best time to control perennial broadleaf weeds.

• Many broadleaf herbicide product labels state to not apply if the day temperatures are 85° or higher as a precaution against injuring the lawn.
• Weeds also need to be actively growing to have the greatest likelihood for good weed control from herbicide applications. Weeds in non-irrigated lawns during dry periods are less likely to be controlled by herbicides. So summer weed control is often spotty at best and waiting until fall is probably your best bet!
• From mid-June on is also the time when crabgrass makes a good bit of growth and becomes much more noticeable. This time of year it may be difficult to control actively growing crabgrass with a single herbicide application. It may take two applications two or three weeks apart to get decent control. (You have to use a post-emergence crabgrass herbicide to control growing plants, crabgrass preventers will not kill already growing plants.)
• If crabgrass becomes a problem this summer make plans to use a pre-emergence herbicide (also commonly called a crabgrass preventer) next spring.
• Again, applying these products when temperatures are greater than 85° increases the risk of turf injury.
• Precautionary statements will be spelled out on herbicide product labels. It is the responsibility of the user to read and follow all label direction associated with any herbicide application.

Weeds in New Lawns

Lawns planted this spring are likely to have new weeds growing along with the new lawn grasses.

• Most herbicide label directions have a recommended waiting period before it is safe to apply them without a risk of injuring the newly planted lawn, however, product label statements can vary greatly in this regard. Products will recommend to delay herbicide application until after the new lawn has matured. This waiting period is typically linked to the lawn having made enough growth to have been mowed 2, 3 or even 4 times.
• Mowing the lawn can help keep the weeds in check if summer temperatures make it unsafe to try and control weeds until fall.
• Hand weeding is always an option.

Water

Most communities have sent out watering guidelines for summer water conservation. The very basic guidelines are where watering is only allowed every other day and is based upon the odd or even home street address. Efficient use of water is good for the community, your lawn and your budget!

• Homeowners vary greatly in lawn watering practices. Some will water to keep the lawn with a good green color while some will not water and allow their bluegrass lawns to go dormant, not watering much at all during extended dry periods.
• When lawns are allowed to go dormant in summer a light 1/4 to 1/2 inch watering every 3 weeks (if not supplied by an occasional rain event) will help the growing points stay alive to regrow with the cooler and moist fall conditions.
• If you do irrigate, the goal is to water deeply and infrequently.
• In the absence of rainfall in July and August applying about 1 to 1 1/2 inches of water per week will maintain good lawn color and growth. This weekly total should be broken up into 2 or 3 watering days per week.
• Soils vary greatly in how fast water can infiltrate into the soil. Water only as long as it takes for water to begin to runoff the lawn. Automatic sprinkler settings refer to this practice as “cycle and soak”. All zones are set for realistic, often shorter run times that avoid runoff. Then additional run times are repeated two or three times over the watering period that day to maximize the amount of water that moves into the soil.
• The best time of day to water is early morning (less wind for better coverage and less evaporation, and the grass leaves dry quickly).

Source:SDSU