Biennial weeds. These flowering plants generally live for two years. The first year consists of leaves, stems and root growth, followed by winter dormancy. In the second year, biennials flower and produce seeds, thus completing their life cycles.
Postemergence herbicides control existing weeds. Unfortunately, because grassy weeds are in the same family as turf grass, these types of herbicides can also harm your lawn. Preemergence herbicides control seeds only—not existing weeds—making them safer for an established lawn (grass seeds are susceptible). They work on most seed-based annuals and perennials.
What’s the Best Weed Control?
Winter annuals. These weeds overlap two calendar years but last only 12 months total. They germinate and develop from late summer to early fall, remain semidormant during the winter and then flower in spring. Come late spring or early summer, they mature and die off as the weather warms.
Hand-pulling grassy weeds can work if there are only a few, especially if they’re annuals. Perennial grassy weeds are harder to control by hand because you don’t always pull up the vegetative structure, which is what sprouts new weeds.
To the untrained eye, distinguishing turf grass from grassy weeds is tough because the two can look identical. But with practice and persistence, you can learn to identify lawn weeds—and even the difference between grass and sedge—by inspecting the primary vegetative characteristics of your lawn.
The shallow root system works in their favor by absorbing as much water as possible before it reaches the deeper rooted plants. Frequent, shallow watering will cause crabgrass to flourish at the expense of other grasses. Less frequent, deep watering is better for your turfgrass, but will not neccessarily hinder crabgrass growth.
There is also the herbicide quinclorac under the trade name “Drive”. This is now available to homeowners and sold by Ortho under the name “Weed-B-Gon MAX Plus Crabgrass Control Ready To Use”. It contains other ingredients to help control broadleaf weeds as well.
Cultural Practices that Help Prevent Grassy Weeds
Foxtails are a summer annual grassy weed. They get their name from the seedhead that resembles a fox’s tail. They can spread quickly in sunny areas but less so in shade. The same preemergents that control crabgrass will also control foxtails.
There is also the herbicide quinclorac under the trade name “Drive”. This is now available to homeowners and sold by Ortho under the name “Weed-B-Gon MAX Plus Crabgrass/Grassy Weeds Control. It is a “Ready To Use” formulation, meaning it comes already pre-mixed. It contains other ingredients including 2,4-D and Dicamba to help control broadleaf weeds as well.
Crabgrass (Late Spring Annual Weed)
Size: To 15 feet tall and wide
Type: Broadleaf annual
Where It Grows: Sunny or shady landscape or garden areas
20 of 34
Where It Grows: Lawn, landscape, or garden areas in sun or shade
Size: 12 inches tall, 6 – 16 inches wide
Where It Grows: Landscape and garden areas in sun or shade
Test Garden Tip: Thistle has an extensive root system that can grow several feet out from the main plant.