Question
I thought I was using a fertilizer for my lawn and had grabbed the Preen from the shelf instead and treated my entire lawn.  Is there anything to stop it from killing the entire lawn or what steps should I take now.  I am in Concord NH  Thanks.

Answer
It depends on the product. Preen makes various brands some of which kills broadleaf weeds (dandelions, clover), others kill grasses, while some kills grasses and broadleaf weeds both.

Check the lable. Is it Preen Gardens, Preen Vegetable Gardens, Preen Lawn Step Saver, Preen Weed & Grass Killer ?

E.g. If you purchased the Preen Weed & Grass Killer type, (the lable says that it contain Isopropylamine salt of glypsophate - see front lable under the drawing) then this product (active ingredient) will kill both weeds and grass on contact.

If you instead purchased Preen Vegetable gardens, then it is an organic product (Corn Gluten Meal) which will prevent seeds from germinating for 6-8 months, but it will not kill grass or plants. This is a good organic fertilizer which can be used to prevent weed seeds from sprouting if applied timely. You have nothing to worry about this one.

If you purchased Preen Gardens then Trifluralin in the product will only prevent broadleaf and gras seeds from sprouting (germinating) but not affect exisiting lawns. So if your product is based on this ingredient, you should not have a problem.

In the meantime, I would like to recommend that you fertilize your lawn in late spring, early fall and late fall. In your area, I recommend late May, early September, and late October. Do not fertilize during hot summer months.

The best you can do right now (unless you applied Isopropylamine salt of glypsophate) is to water the product in well. Use plenty of water. Then do not fertilize until the temperatures comes down from their normal summer highs (early fall).

If you applied Glysophate on your lawn, I doubt you have any chance of rescuing it.

Check lable first..

I keep my fingers crossed.

-- Kenneth