Julia in Woodbridge writes: “Our lawn care service recently treated our lawn with fertilizer and ‘Dimension pre-and-post emergent weed control.’ Shortly afterward, our beautiful green lawn developed brown and yellow patches as if it had been burned. The service told us that it was not their treatment but the excessive rain. Is this possible?”
Poor drainage can kill a lawn, Jules, but not just rain itself.
And the odds of this happening right after a treatment are low to nil. The photo you sent — of a curiously rectangular dead spot — looks exactly like a fertilizer spill, although the extremely high nitrogen product they used could easily burn a lawn at this time of year without any kind of spill being involved.
Just say no to illegal lawn food!
The Dimension that Julia in Woodbridge mentions above is one of those nasty “weed and feed” chemical combinations. The label reveals that the ‘feed’ portion is 19 pounds of nitrogen per thousand square feet of turf — that’s twice the legal limit established by the lawn care laws that went into effect for both Virginia and Maryland to protect the Chesapeake Bay several years back.
That alone is more than enough to burn a cool-season lawn of fescue or bluegrass in the summertime, when cool-season lawns should not be fed at all.
But wait! There’s more!
Julia in Woodbridge said the “lawn developed brown and yellow patches as if it had been burned.”
No surprise there, as that “weed and feed” chemical combo contained twice as much nitrogen as state law allows to be applied in a single feeding — and if it truly was in combination with a fertilizer, you should feel lucky that there’s any lawn left at all.
It’s a difficult concept to grasp, but bluegrass and fescue lawns in our area (the predominant local turf grasses) should only be fed in the spring and fall — never in the winter and never, never, never in the summer, when cool-season lawns are already under a lot of hot-weather stress.
Remember to “warder” (I’m from Philly, OK?) wisely!
If you were lucky enough to receive rain from those Wednesday night/Thursday morning thunderstorms, don’t fret about this weekend’s blazing hot temps. On average, those of us who got rain got an inch that evening, which is the perfect amount — especially for lawns in our region.
Ideally, you would not water again until the middle of next week; or, if the thought of that gives you shpilkes (look it up), at least wait until early Monday morning. (Never water in the heat of the day or ending early in the evening; always time your watering to end just as the sun begins to hit your lawn or garden.)
If you didn’t get rain, adjust your system to deliver several hours of water, ending at 8 or 9 a.m. It takes that long to deliver an inch of water.
Container plants are the exception to the rule
But those rules are for lawns and plants in the ground. Containers are another story:
Hanging baskets made of peat or coir lose moisture rapidly and will need to be watered at least daily.
Hanging baskets made of plastic retain their moisture much better. They should be checked by weight every other day; water if they feel light; wait if they feel heavy.
On the ground? Bigger containers can go longer in between waterings; smaller ones may need to be watered every other day. Always go by weight. Rock the plant container; if it feels light, water; if it fells heavy, just walk away Renee.
Mike McGrath was Editor-in-Chief of ORGANIC GARDENING magazine from 1990 through 1997. He has been the host of the nationally syndicated public radio show “You Bet Your Garden” since 1998 and Garden Editor for WTOP since 1999. Send him your garden or pest control questions at MikeMcG@PTD.net.
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