|I'm using organic fertilizer and weed control. I can't seem to get rid of chickweed no matter what I do. It subsides when the heat comes but its back every Spring.|
|Chickweed is a tricky broadleaf weed because it's a winter annual, one that germinates from seed in the fall and then overwinters. Corn gluten meal pre emergents will prevent weed seeds from germinating but won't kill existing weeds.
Weed-B-Gon is a broad-leaf weed-killer that does kill existing chickweed, but it doesn't do a thing to prevent the next round of chickweed seed in the ground from germinating later in the season.
The long-range, non-toxic goal is to thicken your lawn through good cultural practices (mowing high, testing to make sure your soil is at optimum fertility and acidity levels, top-dressing with compost, etc.) When the grass is thick, there's little room for any weed.
For current control, there's really no organic way to rid your lawn of chickweed in an organic way without killing the grass around it. You'll either have to pull it as best as you can or spot-spray with a broad-leaf herbicide labeled for lawn use. Weed-B-Gon is the best-known brand of those, but look for any product that has MCPP, 2,4-D, triclopyr or Trimec on the label. By spot-spraying only areas where you absolutely need weed control, you're at least limiting herbicide use.
There's some evidence that using weed preventers such as corn gluten meal in September can help stop the main fall sprouting of chickweed. That timing also should help control other winter weeds. Keep in mind, though, that if you're using a weed preventer, most of those also will prevent any new grass seed from sprouting.
You can opt for reseeding and top-dressing in the fall, skipping preventers altogether, digging out bigger weeds in the lawn and spot-spraying smaller patches of things like chickweed and clover.
Hope this information is helpful.