Weed Control: Annual Grasses
If foreign, annual grasses germinate from seed in the disturbed soil below the new sod, they are noticed as paler-green, faster-growing grass in the seams between the rolls of sod. Mowing will even the appearance of the turf and these grasses only live until frost in the fall. The density of the turf will be thick enough next spring to inhibit the germination of annual grasses such as foxtail and goosegrass. If the new sod was not watered sufficiently and the sod pieces shrunk, it would be advisable to use a pre-emergent annual grass preventive treatment in the spring. Pre-emergent products do not allow annual grass seeds to germinate and should be applied in late April or early May.
Weed Control: Broadleaf Weeds
Generally, the density of the turf grasses in new sod is so thick that broadleaf weeds cannot compete. If broadleaf weeds such as dandelions do germinate, they can be controlled by applying a granular weed and feed product or liquid spot treating of the weeds.
Disease and Insect Problems
Diseases and insect problems are hard to diagnose and advice should be sought from an expert. Do not apply chemicals haphazardly before the problem is identified.
There are two conditions that can lead to or contribute to lawn problems and diseases. One is over-fertilization. Do not add more fertilizer than the recommended rate, especially in hot, humid weather or in early spring. Over-fertilizing promotes excessive, fast, top growth and may accentuate disease development.
Thatch is the matting of undecomposed dead stems, leaves and roots in a layer just above the soil surface and below the green, vegetative growth. It is not grass clippings. Too much thatch keeps water from penetrating the soil and the root zone. Roots tend to grow into the thatch rather than deeply into the soil. Insects and diseases can easily establish themselves there.
Thatch layers 1/2 inch or more thick should be aerated to begin to break down this excessive thatch layer. Aeration by machine removes cores of thatch and soil. These plugs of soil deposited on the turf surface contain bacteria that begin to break down the thatch layer. Core aeration also opens up hardened, impenetrable soil and allows water, air and fertilizer to reach the grass roots.
All sodded lawns should be aerated annually after the first full year of growth.