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.
- Select quality “turf-type tall fescue” seed. The University of Maryland publishes a list of Maryland-adapted turfgrass cultivars in publication TT-77. In my experience, local garden centers tend to be more likely to stock better adapted varieties, or you can find these varieties at some professional dealers that also sell to homeowners. These varieties may be more expensive, but they tend to be worth the investment since they exhibit better quality, density, disease tolerance, etc.
- Seeding rate is important. Use a drop spreader or rotary spreader to spread the seed evenly over the area to be rejuvenated. For renovated lawns, aim for 5-7 lbs. of seed per 1000 sq. ft.; for rejuvenation of existing lawns, aim for 3-4 lbs. per 1000 sq. ft.
During rejuvenation is a good time for fall fertilization as well. The University of Maryland Extension recommendation for tall fescue lawns is to apply 0.9 lb. nitrogen/1000 sq. ft. Remember, Maryland fertilizer laws don’t allow you to add phosphorous (i.e. the middle number on a bag of fertilizer should be “zero”) unless you are doing a complete lawn renovation or have done a soil test that indicates phosphorus is needed.
By Geoff Rinehart, Lecturer, Turfgrass Management, Institute of Applied Agriculture, University of Maryland