Ask a Master Gardener: Wait until fall to spray dandelions
If you’re hoping to do the least harm to pollinators, you don’t want to spray a plant that is flowering.
Q: Well, it’s spring and my lawn is full of dandelions again. I don’t want to use chemicals because I don’t want to hurt bees and butterflies, but I’m worried that my neighbors are quietly seething. I’ve got more dandelions than grass. What’s the least bad thing I could spray?
A: I feel your pain. I have the same problem. But given your feelings about spraying, I’m going to suggest tolerating the dandelions for just a little longer.
If you’re trying to use as little chemical as possible, and to use it most effectively, you don’t want to spray your dandelions in the spring. If you spray now, while dandelions are actively growing, you’ll only kill the top of the plant. The roots will live, and next spring your yard will look like this again.
And if you’re hoping to do the least harm to pollinators, you don’t want to spray a plant that is flowering.
Instead, spray in the fall when the dandelions are storing energy in their roots. Research shows a fall application is significantly more effective at taking out the dandelions.
Once you get rid of the dandelions, the best way to keep them gone is to have a healthy lawn. Don’t cut it too short; leave a grass blade of 3 inches or so. Fertilize — but, again, don’t do it in spring. That causes an early flush of green, but weakens the grass.
If your lawn really is more dandelions than grass, you may want to do what’s called renovation. This involves spraying for weeds, cutting what grass remains very short, dethatching if necessary, and overseeding. This would be done in late summer, not now, so you have time to read up on it. There’s more information here:
Written by U of M Extension Master Gardeners in St. Louis County. Send questions to email@example.com.