With spring gardening season right around the corner, lawn questions have been rolling into the Home & Garden Information Center (HGIC). Here I’ll address some of the most common questions about weeds and overseeding.
Dealing with Winter Weeds
In late winter/early spring, we typically see winter annual weeds in thin, under-fertilized, wet, or shady areas. These weeds germinated in the fall and will die as the weather warms up later in the spring. In my observations, this has not been a particularly bad year for winter annuals. They are favored by wet, mild winters and I think we had just enough “bitter cold” in January and a fairly dry stretch through December and January to reduce populations.
Typical winter annual weeds include chickweed, henbit, purple deadnettle, and shepherd’s purse. Options to address these winter annual weeds include hand pulling, spot spraying with a broadleaf herbicide, or waiting until they die once weather climbs to the 60’s and 70’s on a regular basis. For perennial weeds like dandelion which will start to re-emerge later this month, hand-pulling or spot spraying are the best methods for control.
Starting Seeds Indoors – Many types of annual flower plants can be started indoors this month. Generally, most are started 5-6 weeks before they are planted outdoors.
Spring bulbs are emerging and some are even flowering at this time. Exposed leaves may be burned later by very cold temperatures but the spring flower display will not be adversely affected.
Groundcovers are arriving in local nursery and garden centers this month. They are a great alternative to grass where grass won’t grow, where you have heavy shade or tree root problems and on steep slopes.
Q: I didn’t get around to fertilizing my lawn earlier this fall. Is it too late to put down fertilizer now? Should I wait until spring?
A: November 15 is the cutoff date for Maryland homeowners to fertilize their lawns in the fall. According to Maryland’s Fertilizer Use Act that went into effect in 2013, you may not apply lawn fertilizer between November 15 and March 1. The law also prohibits lawn fertilizer applications within 10 to 15 feet of waterways. These restrictions are intended to help protect the Chesapeake Bay from excess nutrient runoff.
With summer winding down — nights are getting longer and days getting cooler — September is a perfect time to rejuvenate tall fescue lawns. Aerating and overseeding now in the fall will make your lawn stronger and better able to resist pests and weed encroachment for next season.
Here are a few points to remember when aerating and overseeding for a lawn rejuvenation this fall:
The aerator you use makes a difference. A heavier, more powerful (> 5 HP) aerator will be more forceful and more effective in creating deeper cores. Ideally, you should be able to aerify to a soil depth of at least 3-4”. Equipment rental stores often have suitable aerating machines available. Remember not to go over the lawn too fast and allow the machine to just “bump” along. Travelling slowly and ensuring the area isn’t too dry will help encourage quality cores to be pulled from the soil.
If you have substantial areas of dead grass or crabgrass weeds, it is probably more effective to remove the dead grass leaves with a hard rake, a “power rake”, or a de-thatcher. The turf seed will need to have good soil contact in order to germinate and grow to provide better coverage. By seeding into an area with a lot of dead debris, the seed may germinate and then dry out – or not “take” at all.