Summer Proofing the Lawn
Lawn grasses in our region can flourish even in drought conditions if you provide proper care.
By Thomas Christopher
Summer is settling in, bringing with it the period of greatest stress your lawn experiences all year. There are a number of precautions you can take, though, to help your turf through the combination of summer heat and dry spells.
Dr. Sidney Bosworth, an extension agronomist at the University of Vermont, recommends a number of measures you can take to safeguard your lawn. To begin, with, he says, sharpen your mower blade – a dull blade shreds the ends of the grass blades. Such a ragged cut not only invites the entry of diseases, it also allows more water to evaporate out of the grass plants, increasing your lawn’s need for water at a time of year when moisture may be in short supply.
Dr. Bosworth also recommends raising the blade on your mower to a height of three inches – he personally mows his lawn at that height all through the growing season. There is a direct correlation between the height of the grass, he explains, and the depth of its roots’ penetration into the soil, so that lawns consistently clipped shorter remain shallow-rooted and less able to withstand summer drought.
The lawn grasses popular in our region of the country, so-called “cool season grasses,” naturally go dormant when the temperatures rise to 80°F and higher. So, if the color of your lawn dulls in July and August, it’s not a sign that your lawn is dying; it’s just taking a break. Trying to force the lawn back into active growth by fertilizing is a mistake. Watering, too, is usually unnecessary, unless a period of drought extends to 4 weeks or more. Even last summer’s drought, which reached historic proportions in southern New England and parts of upstate New York, didn’t permanently harm most healthy lawns in the region. If left un-watered in the spring, in my experience, a lawn will gradually acclimatize to heat and dry weather so that it needs less water in the summer. If you do water, Bosworth recommends that you do it in the morning, as early as 5:00-6:00 A.M., as that schedule minimizes the amount of water lost to evaporation. Evening watering, which may leave the grass wet all night, increases the risk of fungal diseases infecting the lawn. When considering irrigation, though, keep in mind that moist soils in summertime attract egg-laying Japanese beetles and increases the risk of a grub infestation.
I am an enthusiastic fan of white clover, which is more drought-tolerant than most grasses and remains a lush green right through the dog days of summer. It also fertilizes the lawn, absorbing nitrogen from the atmosphere and converting it into natural plant food, and its blossoms provide nectar for pollinators. However, homeowners who are allergic to bee stings may not wish to allow this bee-attracting plant in their lawns, and clover can creep from turf into adjacent flower beds to become a weed.
In general, a robust lawn will be better able to withstand summer stress. Avoid fertilizing in June, July, and August, but if a soil test reveals that your soil lacks nutrients, fertilize at the recommended rate in late August or early September. Using a mulching mower that shreds grass clippings and returns them to the surface of the soil reduces the need for fertilizer, especially phosphorus and potassium (the second and third numbers in a fertilizer’s formula). This practice also reduces the lawn’s need for nitrogen, and if your lawn includes clover, its need for this nutrient (the first number in the fertilizer formula) may be low. Dr. Bosworth also recommends core aerating the lawn annually, in late September or early October.
Following these healthy practices will not only keep your lawn looking better, it will help it cope with the stresses of summertime. A thick, vigorous turf is less prone to weeds, better able to ward off diseases and pests, and better able to subsist on the natural budget of rainfall.
Thomas Christopher is the co-author of “Garden Revolution” (Timber Press, 2016) and is a volunteer at Berkshire Botanical Garden. berkshirebotanical.org
Be-a-Better-Gardener is a community service of Berkshire Botanical Garden, one of the nation’s oldest botanical gardens in Stockbridge, MA. Its mission to provide knowledge of gardening and the environment through 25 display gardens and a diverse range of classes informs and inspires thousands of students and visitors on horticultural topics every year. Thomas Christopher is the co-author of Garden Revolution (Timber press, 2016) and is a volunteer at Berkshire Botanical Garden. berkshirebotanical.org.