What would springtime be without weeds (such as crabgrass)? When weeds show up, it pays to know which ones are annuals and treat them accordingly. Annual weeds, which grow, produce seed, and then die in one year, include annual bluegrass, barnyard grass, common chickweed, crabgrass, foxtail grass, henbit, lamb's quarters, common mallow, pigweeds, prostrate knotweed, purslane, and spotted and prostrate spurges. They grow from previous plants' seed, which sprouts (usually in the spring or summer).
Some advice on tackling annual weeds:
- Pull weeds by hand (or hand-weeder) whenever possible. Try to remove the crown and roots. (Even if all the roots don't come away, many annual weeds will die.) Also, pulling plants by hand is better than scuffing the soil, which can cause more weed seeds to germinate.
- Mow turf to prevent annual weeds from going to seed. (A single barnyard grass plant can produce a million seeds!) Even if you don't kill the plant, it won't come back next season if there are no seeds.
- Mulch garden beds to prevent weed seeds from sprouting.
- Mulch well over weed seedlings in early spring. A thick layer of mulch will prevent the seedlings from reaching sunlight.
- Don't compost any weeds containing mature seeds. Heat from the compost may not kill all of the seeds.
- A healthy, thick lawn in well-drained soil resists the growth of weeds. Aerate, water, fertilize, mulch, and mow correctly.
Pre-emergence products labeled for these weeds can work well, especially when used with the above strategies.