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The Homeowners Column
Control Early Blooming Annual Weeds Now
Extension Educator, Horticulture
The hills are alive with the sound of bloomin' weeds. Many of these early bloomers are winter annuals. The seeds germinate in the fall or very early spring then flower in early spring to form many, many seeds.
These weeds are probably lurking in your garden right now. Winter annuals will appear in areas where the soil has been disturbed such as through tilling, where the dog dug, and where the kids make shortcuts through the lawn.
A few of these early blooming annual weeds include chickweed, speedwell and henbit. Common chickweed, Stellaria media, is a low spreading plant that can grow 4-12 inches tall. It often grows in the shade of trees and shrubs or the north side of buildings. Chickweed has light green, small and ovate shaped leaves with pointed tips. The flowers are small, white with five deeply notched petals. The stems are creeping and often root at the leaf nodes.
Another group of winter annuals are the speedwells, Veronica spp. Corn speedwell, Veronica arvensis, is common here. It is flowering right now. The leaves are small with scalloped edges. The tiny flowers are blue with a white center.
Henbit, Lamium amplexicaule, is often confused with creeping Charlie, Glechoma hederacea. Both have square stems and are in the mint family. Both have lavender to blue tubular flowers. Henbit flowers tend to be more on the purple/lavender range whereas creeping Charlie flowers tend to be more in the blue range. Henbit flowers are clustered at stem tips with clasping leaves (like lacy collars) below the flower cluster. Creeping Charlie does not have the clasping leaves. Both plants have round shaped, scalloped leaves.
The life cycle and flowering time and therefore control measures differ with henbit and creeping Charlie. Henbit is a winter annual and creeping Charlie is a perennial. The original creeping Charlie plants come back every year. Henbit has to start from seed each year. Henbit as a winter annual blooms very early in the spring and well before creeping Charlie blooms. Henbit is blooming right now in east central Illinois. Around here you will often see whole farm fields of henbit in bloom early in the season. Forgetting the weedy aspects of the plant, it really is quite pretty.
Controlling seed production is the key to controlling annual weeds. Early bloomers need to be removed now before they set seed. Luckily most have very small root systems and are easy to pull or hoe. It is probably too late this year for broadleaf herbicides to control the early bloomers. To be effective on annual weeds they have to be used while the weed is actively growing and before the weed flowers. Corn gluten, sold as Concern, WOW and others, is labeled as an organic preemergent control of some weed seeds such as lambsquarter, crabgrass, purslane and velvetleaf. It must be applied 3-5 weeks before weeds emerge, in other words now to control summer weeds. Corn gluten will not control any plants that have already emerged. Check out the Iowa State website at www.gluten.iastate.edu for more details. Be sure to read and follow all label directions on any pesticide.
Control of perennial weeds such as creeping Charlie is in controlling the original plant through hoeing, hand removal or herbicides and in controlling seed production. Despite what you may hear, borax is not labeled for use as an herbicide to control creeping Charlie. At present there is no research to document its efficacy or lack of harm.
With any weed control, accurate identification is important. Check your local library for weed identification books or bring samples to your local U of I Extension office.
Check out the CU Junior Woman's Club Garden Gala April 20 from 9-4 at the Champaign County Fairgrounds.