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Aerate warm-season lawns (zoysia, bermudagrass, centipede) to loosen the soil and improve water and air infiltration.
- Use a device that removes soil cores. Chop up the cores, and, if possible, distribute them by dragging with a span of chain-link fence or a mat.
- Core when the lawn is actively growing so that it can recover from any injury. Moistening the soil the day before makes the job easier and more effective.
Fertilize established Bermuda and Zoysia lawns with 1 lb nitrogen per 1000 square ft of lawn after the lawn is fully green.
Do not fertilize tall fescue or bluegrass after March 15. Fescue roots decline with the arrival of hot weather and cannot support the added top growth. Late fertilization is a recipe for stress.
- Avoid combination products. The best time to use a fertilizer is not usually the best time to use an herbicide, and spreading herbicide over the entire yard is usually overkill. Try to hand-pull or spot treat instead, matching the product to the weed.
- Note that atrazine, a common broadleaf weed control chemical, is very mobile in soil and is the most common herbicide contaminant in drinking water.
Mow cool-season lawns (fescue, bluegrass) to 3–3.5″
- These are clumping grasses and if a clump dies, it is not replaced. Mowing these grasses too short can injure the growing point in the crown.
- Close mowing makes the blades too short to photosynthesize effectively, increasing susceptibility to pests and diseases.
- Weed seeds can germinate more easily because more sun reaches the soil
- Without the sheltering canopy of taller grass, rain hits the soil and compacts it.
Mow Bermudagrass to ¾–1″
Bermudagrass is a running grass. Close mowing stimulates running, making the grass thicker, which suppresses weeds and soil compaction.
Don’t remove more than ⅓ of the grass height
Mowing is pruning and grasses respond by redirecting energy and nutrients away from roots in order to produce new leaves, resulting in a weaker root system. Drastic cuts also increase water loss to stressful levels.
Travel north–south on one mowing and east–west on the next. This keeps growth upright and reduces lawnmower ruts.
Leave grass clippings on the lawn. They decompose quickly and can return up to 25% of the lawn’s fertilizer. If clippings are too plentiful, use them as mulch or let them dry a bit and then add to your compost.
Apply the first round of crabgrass prevention in late March–early April.
- Because spring weather varies, use flowering as a cue for when to apply pre-emergent crabgrass control. Apply while forsythia is blooming or by the time that dogwoods are blooming (late March–early April), then apply a second round about 6 weeks later. Learn how to maximize the effectiveness of pre-emergent control.
- Cool-season lawns need to rest for the summer, so use a pre-emergent that does not contain fertilizers. Products containing dithiopyr also provide post-emergent control for young crabgrass.
Keep turf dense and mow cool-season lawns no shorter than 3.5″ to reduce sprouting of summer annual weeds. Weed seeds need light in order to germinate.