Weed Grasses - Bent, Crab, Quack, and Tall Fescue

To many homeowners, any grass that doesn't look like the Kentucky bluegrass sod that they had when the lawn was new is a weed grass - many call that weed grass "Crabgrass". Actually, there are several undesirable grasses that can invade the home turf.

Crabgrass has run rampant in many lawns the last few summers. Crabgrass is an annual- this means each autumn it dies- but each spring it comes up from seed. It germinates in mid May. By the time it is noticeable, you see short, light green, blades of grass along the driveway or walkways and in the thin areas of the lawn. It grows quickly, and before long it spreads out flat, often smothering the existing grasses. The leaves are now distinctly hairy, and long seed heads develop. As it gets cooler in September it turn purple. After the 1st good frost it dies and by spring it has pretty well decomposed.

Control of Crabgrass . A healthy thick lawn will naturally crowd out crabgrass. Regular feeding and aeration help to develop thick lawns to discourage crabgrass and other weeds. Mow the lawn at 2 1/2 to 3 inches high. Water deeply once a week (on average) rather than every other day. Crabgrass can be controlled because it dies in the winter. Products are available that prevent germinating seeds from growing in the spring. If necessary, resod bare spots. Re-seeding will also thicken the lawn. Add grass seed in the fall (as early as late August). Fall is the best time because crabgrass controls can interfere with lawn seed germination. (Normally we avoid putting crabgrass controls on newly seeded areas so as not to damage grass seedlings. - Of course, without the control, crabgrass may sprout in these areas). The new grass seed will fill any spots left thin by the crabgrass. Add the seed even before the crabgrass dies- the crabgrass will protect the newly germinating grass plants.  

Quackgrass - this weed grass is often mistaken as crabgrass. Its leaves are coarse, wider than the regular grass types in the lawn. If you find "crabgrass" in your lawn in April or May, it is most likely quackgrass as quackgrass lives through the winter. Quackgrass is generally most noticeable a few days after the lawn has been mowed. It grows quickly. You cut the lawn on Tuesday and it seems that by Wednesday night the quackgrass is already higher than the rest of the lawn. The new growth is light green, older blades have a blue-gray-green colour. If you pull on the grass you may find white underground stems (rhizomes).

Quackgrass is very deeply rooted. This means that is able to survive the lack of moisture better than lawn grasses. Quackgrass can continue to spread even in drought conditions.

Control of Quackgrass is not easy. There are no products that selectively kill quackgrass. If you have quackgrass in a small area, you could do some minor renovating to remove it. Often, lawns are infested with quackgrass in 25-40% of the lawn. At that point most people say that they are not prepared to do major renovation of half the lawn or more. "We'll live with it, at least it's green."

After the grass has turned yellow, then you can dig it up. Or, if you like, turn it over and sprinkle grass seed or resod.

On an ongoing basis, mow the lawn regularly at a 2 2/3 to 3 inch setting. Do not allow the quackgrass to grow tall. Regular fertilization programs will help to crowd out the quackgrass as turfgrass responds better to feeding than quackgrass.

Bentgrass is great for the golf green. It is noticeable for its very fine textured blades, light green colour and above ground stems (a surface rooter) that often lay flat on the soil surface. It is a problem on home lawns because it requires a great deal of pampering. It does not withstand our winter weather conditions well. It also tends to turn brown with the hot, dry weather. The stems often turn brown, exposing dead areas when the lawn is mowed. Bentgrass grows vigorously and will spread very quickly in home lawns.

Control of Bentgrass. As with quackgrass there aren't any products that selectively control bentgrass. If you find a small patch remove the grass and resod. If you have more than you care to dig up, rake hard in the spring to remove as much as possible and re-seed. Use an infrequent watering routine as this will discourage the shallow rooted bentgrass and overwatering or extreme wet weather will encourage its growth. If there is a lot of bentgrass, a new lawn is the only way to get rid of bentgrass. Incidentally, when mowing, mow the areas with bentgrass last. Small pieces of bentgrass will root in other areas if the right amount of moisture is available

Tall Fescue - There are a number of desirable fescues in most lawn seed mixes, but Tall Fescue is classified as a "weed grass". It is a very unsightly coarse bladed grass that spreads first by seed and then later by tillering. It is hard to pull out of a lawn and if pulled, leaves a large divot. We do however recommend pulling it and re-seeding the area as needed. Take caution to not purchase a seed mix with Tall Fescue in it (you need to ask) for your seeding or re-seedings.