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Even though that silly Pennsylvania groundhog predicted six more weeks of winter, I don’t think you’ll have to worry about that in our neck of the woods. After a cold blast, we’ve had a few warm days. That means it’s time to get some late winter chores done.
“Crabgrass preventers” are popular ways of dealing with some of the weeds in our lawns. Folks in the business call them pre-emergence herbicides because they control weeds that haven’t made an appearance yet. While they are certainly good tools where necessary, we’ve learned some interesting things about these products.
Two of the more popular pre-emergence herbicides are pendimethalin, which is sold under a multitude of names including Pendulum and dithiopyr that is sold as Dimension. Both are effective at controlling lots of annual grasses such as crabgrass and many broad leaf weeds. What we’ve learned about these materials is that, especially on centipede and St. Augustine, they will negatively-affect the grass roots. I’m not saying you shouldn’t use these products on centipede and St. Augustine, but there are some things you can do to minimize the root damage.
Two applications at the lowest labeled rate will give you the same control as one at the high rate. Apply now and again in six to eight weeks. Be especially careful during the spring transition or “green up” period. All turfgrasses are more sensitive to weed control applications then.
If you have a centipede or St. Augustine lawn that has lots of bare spots and is struggling, leaving off the pre-emergence weed control is a smart move. The herbicides often prevent the grass from successfully filling bare areas.
The other thing we’ve learned in working with these pre-emergence products is the timing on the first application isn’t nearly as critical as we once thought. When the soil and air temperatures are low, they just sit there; so early applications don’t really hurt you going into the spring.
Figuring out why your lawn is struggling should be high on your priority list. Start with the oft-recommended soil samples. Check for nematodes and ground pearls if you have sandy soil. Think about shade and traffic issues. Sometimes it’s just not worth trying to grow grass in some places.
It’s just about time to get some of those pruning chores done. Go ahead with the Knockout roses, since they are already trying to put out new growth in lots of places. Ornamental grasses that look a little rough around the edges should be sheared. Hollies and other evergreens can also be shaped up as well as summer-blooming plants like crape myrtles and rose-of-sharon. Wait until after your late winter/early spring flowering plants like forsythia and azalea finish blooming if you care about salvaging the flowers.