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St. Patrick’s Day was last week and some of our lawns are already “wearin’ a bit ‘o the green” because of some warm days. This move out of dormancy means that right now is the wrong time to stress your lawn with fertilizers or weed control products.
Even though it seems illogical on the surface, one of the worst things you can do right now is apply nitrogen fertilizer to centipede, Bermuda, zoysia or St. Augustine lawns.
You might think adding some extra nitrogen when you see that first bit of green is the right thing to do, but there is this strange phenomenon called spring root decline. During the transition or green-up period, our grasses slough off most of their fibrous roots. So, your turf is struggling to survive the ups and downs of our normal early spring temperatures with a poor root system.
Forcing a plant to grow leaves by adding nitrogen when the root system isn’t functioning well only aggravates a difficult situation.
A good time to think about fertilizing your lawn is about the same time you write that check to the Internal Revenue Service—April 15. Wait until the grass is completely green and the danger of below-freezing temperatures is over. Your lawn will be healthier and happier during the coming growing season.
One of the confusing things about this is that you read and hear recommendations to fertilize lawns starting in February. Those recommendations make lots of sense for cool-season grasses like tall fescue and Kentucky bluegrass. Our summers are just too long and hot for cool-season grasses to survive consistently.
Weed-and-feed products are popular because they’re relatively easy to use and don’t require mixing materials in water and spraying. One problem is the time to apply fertilizer and the time to apply weed control products don’t usually line up well for warm-season grasses.
Most weed-and-feed materials also have too much nitrogen for most of our grasses and many contain high rates of broadleaf weed killers such as 2,4-D that may injure centipede and St. Augustine. Products designed for centipede and St. Augustine that contain atrazine are acceptable but should not be applied until mid-April or later because of the nitrogen fertilizer.
Once we move into the main part of the spring transition, you should think twice before applying any kind of weed control product. There are formulations of broadleaf weed controls like Trimec and Speed Zone for all of our grasses, but even labeled rates may be a negative during this sensitive time. If you must apply these products, divide the maximum rate in half and make two applications about two weeks apart.
Al Hight is the county extension director and horticulturist with the Brunswick County Cooperative Extension Service. Call 253-2610 or e-mail email@example.com.