By Eric Barrett
OSU Ext. educator
Weed control is more important now than in the summer months.
Winter annual weeds are the tiny seedlings you barely notice in landscape beds and in thinning areas of the lawn this time of year. They are small now, but they will expand rapidly starting with the first warm, sunny day at the end of February and into March. They will plague your spring garden and hinder the warming of the soil in your vegetable garden.
These three are increasingly challenging because of their lack of competition during the winter months:
This is the No. 1weed brought to our office for identification each spring, and is most known by the way it explodes when brushed, sending seeds away from the plant to grow even more weeds. It is a member of the mustard family. It grows as a rosette on the ground. The soft, thin, heart -shaped leaves turn to compound leaves with two to eight alternate leaflets. Before you know it, white flowers appear on upright stalks that quickly turn to pointed seed pods. It is said that one of these plants can produce up to 5,000 seeds in five weeks.
This weed has square stems and tiny purple flowers in early spring – March and April. You will see fields of them along the road in March – it gives off an overall purple hue. The stems are even purplish-brown. Leaves are rounded, almost heart-shaped, and have tight veins. They surround the stem and are almost velvety to the touch. The plant is just around as seedlings right now. You can identify the round leaves and they are a lime-green color as seedlings. The mature plant will grow to about 8 inches tall. A similar weed is henbit, which has a more curled leaf and tends to vine more than be upright.
This is a very soft plant, sometimes called bindweed or winter weed. It forms a dense mat where it grows. The seedling has spade-shaped leaves and is lime green. The stalk is hairy, the leaves are smooth. It is most recognizable by its white flowers that appear from early spring until late fall. The flowers are daisylike with a green center and tiny – 3-6 mm wide. The plant branches rapidly along the ground.
Control this time of year should focus on using a weed trimmer or a hoe to mechanically remove seedlings. Consider a plan to repair/reseed thinning areas of turf where these weeds grow. Freshen up mulch and increase thickness in areas such as flower beds and landscape plantings. Pre-emergent herbicides could have helped earlier in the year, but are of little use now.