Seeds begin to germinate in the spring from seeds buried less than one inch in the soil. Cotyledons are covered on both sides by velvety hairs. The main vein is easily visible from both sides of the leaf. Each cotyledon usually has a distinct shape; one is roundish, and the other is slightly heart-shaped. Stalks are green, sometimes having a purplish tinge to them. The first true leaf is heart-shaped and has a round tip. Subsequent leaves maintain that shape with a sharper point.
The leaves of mature velvetleaf are arranged alternately and remain covered in soft hair, while the stem becomes coarse woody. The stalks of the leaves are 4 to 8 inches long and connect to heart-shaped leaves. When crushed, the plant releases a distinct odor.
The velvetleaf blooms from July through August. Flowers of the velvetleaf grow on the upper leaf axils and are typically by themselves. They grow to be about 3/4 inches wide with yellow to yellow-orange petals. The flowers produce semi-rounded, cup-like seed capsules that contain up to 30 seeds each. Each plant produces between 700 and 17,000 seeds, depending on the size of the plant.
Velvetleaf is listed as a noxious weed due to its ability to outcompete other plants for valuable resources. It is invasive and has been known to reduce yield by up to 34 percent in corn if left uncontrolled. Seeds can remain viable for 50 or more years, making it very difficult to eradicate once a seed bank has been established. Its leaves and seeds release toxins that inhibit the germination and growth of surrounding plants.
Removal of velvetleaf is very difficult once it has been established, so typical preventative measures are extremely important. Intensive tillage in corn was known to reduce seed levels by 40 percent per year, but that is without any seed production. Cultivation has been used as well, but like tilling only produces short-term effects. If crops emerge well ahead of velvetleaf, its effect on yield is much smaller.
For proper control, preemergence and postemergence herbicide application are a must. It is recommended that multiple applications are used. Postemergence pesticides are best applied during the day, as the leaves droop at night and return to being mostly horizontal during the day. Please contact your local weed specialist to learn what is most effective in your area and how to use it best. Always read and follow all label instructions.