Digging In: Turf Wars
The most common questions I’m fielding these days at the nursery involve lawn care, second only to “How late are you open?” Most of these queries focus on fertilizing, lime application, and weed control, so here’s my take on these three things:
Fertilizing: The best time to fertilize turfgrass is in the fall (except for zoysia, Bermudagrass, and other warm-season grasses common in the South). But if you forgot, you can still do it in spring, through early June. Don’t fertilize your lawn in the hottest summer months, as grass tends to go dormant during this period, and the organic compounds in fertilizer (typically nitrogen, phosphorus, and potassium) can burn foliage at high temperatures. Never apply fertilizer to frozen ground, as it will just run off.
It’s important to find out what kind of grass you have. If you don’t know, ask your lawn service. Don’t have a lawn service? Take some samples to a local Plant Clinic and ask the volunteers to look it up in their reference materials. Here’s why it’s important: the kind of grass you have dictates how much nitrogen to apply to your lawn. Kentucky bluegrass and perennial rye, for example, like 3 – 4 lbs. of nitrogen per 1,000 sq. feet. Tall fescue – which is the most highly-recommended type of grass for Maryland – likes 2 – 3 lbs of nitrogen per 1,000 sq. feet. Fine fescue and zoysia grass need only one to two pounds per 1,000 sq. feet.
Next, check the fertilizer bag’s label. There are three numbers on every bag (#-#-#), which represent percentages. The first number is always Nitrogen, which is the most important element for above-ground growth. (The other two numbers are phosphorus and potassium, and they work below-ground on the roots.)
Now for the math. To determine how much nitrogen is in a bag of fertilizer, multiply the N number by the total weight of the bag. For example, if the bag weighs 40 lbs. and it says 10-6-4, you would do the following: .10 x 40, which equals 4 pounds of nitrogen. Now, check the bag for how much coverage it provides. If it says it will cover 5,000 square feet, divide 5,000 by 1,000. Divide the amount of nitrogen in the bag (4 lbs.) by this amount (5) to get 0.8 pound per 1,000 square feet. If, for example, you have fine fescue and need to apply 2 lbs. of nitrogen per year, you’ll want to apply this particular fertilizer three times per year (2 divided by .8 = 2.5, rounded up to 3). It would be best to apply the fertilizer twice in the fall (say, early October and again right before Thanksgiving) and once more in early spring.
My head hurts now, so enough about the nitrogen. Onward to liming and weed control.
Lime is something that people seem to feel the need to spread around on their lawn whether they know they need it or not. You really only need to lime your lawn if the soil is too acidic. Test your soil’s pH before you lug home a 50-pound bag of lime. The best pH for healthy grass is from 6.0 to 6.5. If your soil is already too alkaline (i.e., a pH higher than 6.5), an application of sulphur is in order.
As for weeds, there are two kinds of turf weeds: broadleaf and grassy. Broadleaf weeds are things like dandelions and chickweed. Grassy weeds are, well, grassy! Think crabgrass. Weeds are opportunists, and mowing your grass too short is an engraved invitation to weeds. Keep your mower height at its highest, and your weed population will shrink. Consider grass-cycling (leave clippings on the lawn) and rake the turf gently once a month or so to keep thatch from building up and to help oxygenate the turfgrass’ roots.
Pre-emergent weed control gets a lot of attention, but you need to apply these products now, before weeds really take off and start producing seeds. Some pre-emergent products have fertilizers built in; check the label. If you’re planning on re-seeding your lawn, don’t apply a pre-emergent, because it could interfere with your grass seed germination.
Stumble it!