Garden Doctors: Avoid wind when applying Roundup
Published: Saturday, November 3, 2012 at 3:00 a.m.
Last Modified: Tuesday, October 30, 2012 at 2:46 p.m.
Pam Nelson writes, I'd love to plant some wildflower seeds, but the area I have in mind is very large.
I notice that in your article, you mention pulling the weeds by hand, at least the first time. Do you ever use Roundup? I don't know how long it would stay in the soil, so maybe using it would also kill the new seeds that would soon be planted.
Is there ever a good time to use this product, in your opinion? A botanist whom I know does use it regularly, but perhaps not to prepare a bed for new flowers!
To answer your question, yes, I do use Roundup, labeled glyphosate on the container by different manufacturers, and have used it successfully to rid a site of undesirable weeds and grasses before planting wildflower seeds (when hand pulling weeds was next to impossible).
Glyphosate is not going to inhibit the germination of new seeds. It is a systemic that only translocates (moves) through the targeted/treated weeds and eventually kills them. Glyphosate is not effective when weeds and grasses, i.e. Bermuda grass, are in their winter dormant stage of growth.
However, a word of warning is prudent when using glyphosate; it should never be used when it is windy as it can kill desirable nearby plants even if a small amount of spray hits the foliage or stems. Spot treatment with a small hand sprayer is efficient and it is easy to control any spray drift, especially if the area to be treated is not extensively covered with weeds or turf.
Roses are a perfect example of sensitivity to drifting Roundup spray resulting in plant damage and/or death.
Planning a wildflower garden takes some time for successful results. If you choose to use glyphosate, it should be applied when the weeds are growing actively such as in early spring or summer and the weather is dry for a day, thus allowing the chemical to be effective. If the weed problem is extensive and a new crop of weeds appears, a second application will be necessary. The trick is to water and fertilize the site to encourage more vigorous weed growth, then apply the Roundup (glyphosate) so it will be more effective. Now you will be ready to scatter seeds in the fall when the site is free of undesirable weeds.
There are some additional methods you may want to consider to rid a large area of weeds when preparing the site for wildflowers:
Here is an easy sowing and germination tip:
Using bulk wildflower seeds labeled for successful planting in our Northern California zone, fill a container with the seeds mixed with horticulture sand. The planting site should be sunny, weed free, raked smooth, level and dry. Sow half of the mix walking up and down the site in one direction and reverse the sowing by walking up and down perpendicular to the first direction.
Now this is the fun part — walk/dance the Texas two-step back and forth over the seeded area so the seeds are making good contact with the soil. Using a non-woven, floating row-cover material, cover the entire area, anchoring the edges with boards or stones. Water the area thoroughly and continue to keep damp until you see new plants sprouting, have an inch or more growth and appear well established before removing the cover.
The row-cover material keeps the seeds from floating away during irrigation, excludes birds from dining on the seeds, allows the soil to be consistently damp during germination and helps keep the soil temperature fairly even.
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