OK, grass is probably on your mind. It's on my mind, particularly on how it can grow 3 feet in 24 hours. I'm exaggerating, but not that much. This is the weather for grass. And accordingly, many people want to know what to do to the lawn and when to do it. When in doubt, it's always a sure thing to turn to the experts at Penn State University. Peter Landschoot, who is a turfgrass specialist at the college of agricultural science there, has obligingly come through with lawn advice you can depend on.
Didn't put that crabgrass treatment on yet? Landschoot says those of us in Pittsburgh should apply crabgrass treatment yearly between March 15 and April 15. Once you can see crabgrass growing in the lawn, it's too late. Don't waste your money. So we've missed the deadline for that, but there are plenty of other things to do.
Landschoot gives the following yearly calendar for lawn management.
Seeding. Establishing a new lawn from seed should be done in late summer to early fall because there are fewer competing weeds in the fall and the soil may be too wet in the spring for good seeding. Also, the grass will have the cool of the fall and the spring to establish itself before enduring the stress of summer heat and drought.
*Overseeding. Seeding onto thin turf or bare patches can be done in late winter, spring or early fall. Landschoot recommends perennial ryegrass for overseeding more than any other turfgrass species. Make sure the seed comes in contact with the soil and has space to germinate and develop. "Don't just throw the seed onto dead grass," says Landschoot. "The soil surface should be roughed or scratched with a rake."
Sod. Homeowners can apply sod at any time of the year, if irrigation is used. If you sod in the summer, of course, you'll have to water more frequently and the grass will take longer to establish.
Fertilization. Grasses generally need more nitrogen and potassium than soil can provide. A soil test can determine how much fertilizer your lawn needs. (Soil testing kits are available at Penn State Extension offices and many area nurseries and garden centers.) Once the amount of fertilizer required is determined, it can be applied once in late spring and again in late summer and/or early fall. "If the soil test reveals the soil is too acidic, with a pH lower than 5.5, lime should be added also," says Landschoot. Apply lime in the fall, spring or winter because rain or snow helps work limestone into the soil.
Dethatching. Thatch is the interwoven layer of dead grass roots and stems lying directly below actively growing grass. Thatch is bad because grass roots can grow into the thatch, making them susceptible to drying out. Thatch can be removed manually with a thatching rake, or mechanically with a rented dethatcher. Landschoot recommends removing thatch during periods of cool weather, like late spring or early fall. Do not thatch during periods of high temperatures or drought.
Aeration. This process is completed by removing plugs of soil from the turf, which in turn lets moisture and nutrients reach deeper into the soil. Aeration also reduces soil compaction and can reduce thatch. Again, Landschoot recommends that homeowners aerate during cool weather periods -- early spring or fall.
Weed control. Crabgrass can be controlled with pre-emergent herbicides in early to mid-spring. Broadleaf weeds like dandelions and ground ivy are controlled by plant-specific herbicides that are applied while the weeds are actively growing in late spring or early fall.
Diseases. Turfgrass diseases can occur any time of the year, says Landschoot. Get an early and accurate diagnosis, because control can be difficult once the problem has spread. If you aren't sure what is wrong, take a sample to your local garden center or nursery and ask.
Insects. Most insect problems occur from late spring to early fall. Japanese beetle grubs feed on turfgrass roots in May and June, and again in late August, September and early October. The best time to control grubs is in late summer, when they are small and tend to feed near the soil surface. Insects that feed on leaves and stems, such as cinch bugs and sod webworms, are prevalent in June, July and August. Planting or overseeding resistant grasses and watering drought-stressed lawns can help alleviate insect damage.
Here's a few more tips from Landschoot.
Mowing. Two to 3 inches is the ideal height to cut grass. Cutting it shorter makes lawns more susceptible to heat, disease and drought stress. Don't take off more than one-third of the leaf blade at any one cutting. Cut the lawn as growth dictates. In spring, more than once a week may be needed. During hot, dry conditions, there may be no need to mow.
And leave those lawn clippings on the lawn, or compost them, says Landschoot. Recycling clippings is beneficial to the lawn and saves the work involved in raking or bagging. If you leave clippings on the lawn, it will cut down fertilizer needs by as much as one-third. If no herbicides have been applied to the grass, homeowners can rake the clippings and use them as mulch or compost them.
My annual roundup of what's new at garden centers and area nurseries is planned for May 20. Area business owners can send us a list of new and/or interesting plants for inclusion. Please limit the list to about five items, and we reserve the right to edit. Include the name of the business, hours of operation, location and a phone number where we can reach you during the day. Submit lists via e-mail to sbanks@post-gazette.com or fax them to 412-263-1313.
