Controlling weeds while protecting trees and shrubs
I have a 120 x 8 ft mulch bed of young shrubs and trees. The weeds went totally wild this summer and I am trying to bring the area under control this fall. It is a mixture of tall 2 1/2' grass-like weeds, ground ivy and a few other weeds. What is the best way to remove the weeds? I was thinking of weed wacking then covering the area with 2-3" of double-shredded oak bark mulch. Is this a sensible approach? Will all the weeds come back next spring or will I just have to stay on top of it? Would a spray of herbicide help? Questions: 1. Should I weed wack? 2. How much mulch? 3. Are herbicides useful at this time of year? 4. Will they harm the plants? 5. Other suggestions?
You are not alone. With all of the rain it was a challenging year to keep up with all of those very happy weeds.
We can help.
The first step is identifying the weeds you have and knowing something of their life cycle. For instance, cutting it all back and mulching would be helpful for annual weeds that germinate in the spring and die with fall frost, but perennial weeds that come back each year will just come right up through the mulch next season.
Here is our weed photo gallery to help with identifying: http://extension.umd.edu/hgic/topics/lawn-weed-identification
We see crabgrass, which had a banner year and grew to cover large areas, so check that out.
Your last two photos are out of focus, but we think we see dandelion, and you likely have mock strawberry, creeping charlie, invasive Japanese Stiltgrass, Pokeweed (tall, tap-rooted perennial with red stems and purple drooping berries) and perhaps the tufts that are still green are a grassy perennial weed.
Using an herbicide right now is not what we'd recommend. Plants need to be actively growing and now it's getting late.
You could weed wack everything low, and then mulch with about 3", but keep it back from the trunks and stems of your desirable plants.
You could apply a pre-emergent herbicide which stops germination in late winter, early spring for some of the annual seeders.
We'd expect you will see the perennial weeds pop through the mulch next season, and then we suggest spot-treating with a non-selective herbicide product containing the active ingredient glyphosate to kill back through the roots.
Follow label instructions carefully and do not let the spray contact your plantings.