Garden Doctors: Avoid wind when applying Roundup

<p>Pam Nelson writes, I'd love to plant some wildflower seeds, but the area I have in mind is very large.</p><p>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.</p><p>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!</p><p></CF>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).</p><p>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.</p><p>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.</p><p>Roses are a perfect example of sensitivity to drifting Roundup spray resulting in plant damage and/or death.</p><p>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.</p><p>There are some additional methods you may want to consider to rid a large area of weeds when preparing the site for wildflowers:</p><p><CF103>1. </CF>Put down thick layers of newspaper now and cover the newspaper with 2 to 3 inches of organic mulch — not bark. The newspaper will smother the weeds, decompose over the winter months and then provide a nice seed bed for early spring planting. We usually plant wildflowers in the fall in our area, but wildflowers such as California poppies and other native annuals can be planted in the spring and they will provide a nice show of color in the summer months. Perennials will take longer to become established. Choose a mix that does not need a period of stratification (winter cold temperatures) to germinate.</p><p><CF103>2. </CF>Prepare a hot sunny site for seeding by using the soil solarization method. Rototill the site, rake it smooth and then water the area thoroughly to encourage new weeds to emerge. Cover the prepared area with overlapped clear plastic mulch anchored and buried at the edges with heavy stones. The clear plastic should stay in place throughout the summer. Grasses and weeds will be killed in the top two inches where germination takes place. In the fall, remove the plastic, DO NOT cultivate or disturb below the solarized level so as to minimize new weeds from germinating, but scatter the wildflower seeds in the fall according to the wildflower package directions.</p><p>Here is an easy sowing and germination tip:</p><p>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.</p><p>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.</p><p>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.</p><p>(Send your gardening questions to The Garden Doctors at pdgardendoctor@gmail.com.</p><p>The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.)</p>