Slit-seeding a Lawn
Preparation
Remove undesirable weeds from the lawn. If more than 50% of the
lawn is infested with grassy weeds, you'll need to completely renovate and
spray the entire lawn with a non-selective herbicide such as Roundup or
Finale. In most situations only partial renovation is necessary.
Use a selective broadleaf herbicide to control broadleaf weeds and
non-selective herbicides to spot-spray patches of perennial grassy weeds.
Be sure to read the herbicide label for guidelines on how soon you can seed
or sod following the application.
Reduce competition
The remaining desirable turf
will compete with the new grass seedlings for water, sunlight and
nutrients. To lessen this competition, scalp the existing turf with a lawn mower. Mowing at
half the normally recommended mowing height will open the turf canopy and
stress the existing grass plants slightly. This reduces their
competitiveness and creates a more favorable establishment environment.
Cultivate the soil
Follow the close mowing with cultivation. The key concept in
renovating is seed-to-soil contact, which helps ensure young seedlings will
successfully become established. The less desirable the existing turf is,
the more you need the newly planted seed to develop into a solid stand, so
the more extensively you need to cultivate (to create more seed-to-soil
contact). In other words, match the type and extent of cultivation with the
severity of the problem.
Slicing and slit seeding are less disruptive than
aeration and dethatching, but create a poorer seedbed. If the need is
great, aerate in several directions. This will help provide more sites for
seed to establish. If dethatching before slit-seeding, several passes may be
necessary. However, excessive dethatching can be harmful. It is important
to leave a small amount of stubble or to prevent
erosion of the seedbed and to shade new seedlings during establishment.
Choosing an appropriate seed variety
Obviously, you should avoid overseeding
with new varieties or species that will clash with existing
turfgrasses. Thus, warm- and cool-season turfgrasses should never be mixed,
and it may be best to avoid
certain cool-season mixes.
Be sure you choose suitable varieties. For example, look for
varieties that are resistant to common diseases in the area. If shade contributed to the original lawns decline, look for
shade-tolerant varieties.
Seeding rates
Once the seedbed is ready, calculate
the size of the area you'll seed. Knowing the
square footage you will overseed you can then determine the amount of seed
you'll need. Adjust the seeding rate
according for lawns that may need more seed.
