The dry conditions that have persisted across Iowa in recent weeks have created extra chores for many home gardeners. It also has raised questions about proper cultural practices. The following questions and answers deal with the effects of the dry weather on lawn care practices.
Q. My lawn has been dormant for several weeks. Would it be advisable to start watering the lawn?
A. Generally, turfgrass can remain dormant for 4-6 weeks without suffering significant damage. However, lawns are in jeopardy of dying if dormant for longer periods. To insure survival of the turfgrass, it's best to water lawns that have been dormant more than 6 weeks. Apply 1 to 1 1/2 inches of water in a single application. Water again 7 days later. The grass should begin to green up nicely after the second application.
Q. Would it hurt the turfgrass to fertilize the lawn when it's dormant?
A. Fertilizing a dormant lawn will not harm it. However, the turfgrass may not receive the full benefit of the fertilizer application. If a granular fertilizer remains on the soil surface because of a lack of rain, some of the material may actually volatilize into the air. It probably would be best to wait until the weather pattern changes (hopefully soon) and it begins to rain before fertilizing the lawn. Fertilizer applications can be made anytime in September. Late October/early November is also an excellent time to fertilize the lawn.
Q. Are broadleaf herbicides effective when applied during dry conditions?
A. Broadleaf herbicides are most effective when applied to weeds that are actively growing. Because of the dry conditions, the leaves of some weeds have curled up, and others have wilted. Plus, granular broadleaf herbicides may have difficulty sticking to the weed foliage. As a result, granular applications of a broadleaf herbicide to drought stressed weeds will be less effective. Broadleaf weeds that are actively growing in dormant lawns can be effectively controlled with foliar spray applications of broadleaf herbicides. There is low risk of lawn injury when broadleaf herbicides are used on summer dormant lawns. Fortunately, there is still plenty of time to apply broadleaf herbicides to lawns. In Iowa, mid-September to early November is the best time to apply a broadleaf herbicide.
Q. Can I aerate my non-irrigated lawn this fall?
A. Lawns should be aerified when the turfgrass is actively growing. Also, aerification is most beneficial when the aerifier is able to remove soil plugs that are 2-3 inches long. At this time, it would not be advisable to aerate non-irrigated lawns. Most non-irrigated lawns are dormant. Plus, the aerifier's metal tubes or tines would have difficulty penetrating the hard, dry soil. It may still be possible to aerate the lawn this fall if the rains begin to fall or if you're willing to irrigate the lawn. Otherwise, it may be best to wait until spring.
Q. What can I do if my lawn has died or was in need of reseeding this fall?
A. Fall is the best time to renovate and reseed weak or damaged lawns. If you were waiting to reseed your lawn, the dry conditions may actually help you. The dormant, straw-like grass can easily be power raked or verticut to make a good seed bed. If the ground is too hard for the power rake to nick the soil, water the lawn two days before the verticutting and seeding operation. Verticut, seed, fertilize, and water before the end of September and you should be able to completely rejuvenate your lawn this fall.
This article originally appeared in the 9/12/2003 issue.