Crabgrass
Crabgrass is a summer annual. It germinates in spring and dies in the fall. It has a different texture and color than turfgrass creating a non-uniform lawn. It also sets seeds and can spread throughout the landscape. Lawns that are not well maintained are prime targets for crabgrass invasion.
It is easiest to control crabgrass before it germinates using preemergence. May 1 is typically when crabgrass is expected to germinate throughout much of Kansas, but this does vary depending on location and weather patterns. Many homeowners use signals from nature to determine preemergence timing.
A common guideline is to apply crabgrass preemergent when redbuds are in full bloom. While this is an indicator, it’s not going to provide 100% accuracy since microclimates exist within each landscape. In warmer areas of the landscape, crabgrass is likely to germinate earlier.
Soil temperature is a useful indicator to predict crabgrass germination. Using the K-State Mesonet you can access the average soil temperature at a two-inch depth over the past seven days. When the daily average is 55 degrees F for about five days, research suggests this is the time to apply crabgrass preemergence.
Why Weeds Invade Lawns
Instead of combatting weeds all season, take a proactive approach to prevent weeds. Here are some common reasons why weeds invade lawns.
- Improper Mowing: Mowing too low and too infrequently thins the turf, allowing weeds to get started.
- Improper Watering: Frequent watering encourages weed seed germination, disease, thatch, and a shallow-rooted turf that is less competitive with weeds for soil moisture and nutrients.
- Improper Fertilizing: Fertilizing too much, too little or at the wrong time may benefit weeds more than grass.
- Insect and Disease Injury: Weeds rapidly invade lawns that are thinned by insects and diseases.
- Compacted Soil: Soil compaction is a hidden stress on the turfgrass root system. The grass is unable to compete effectively with weeds.
- Excessive Wear: Turf areas used for recreation and sports are subjected to wear and compaction.
- Wrong Kind of Grass: The wrong kind of grass for the location will gradually decline and be invaded by weeds.
- Environmental Stress: Weeds often take over a lawn after it has been weakened and thinned from weather-related stress.
- Thatch: Excessive thatch causes shallow-rooted grass and contributes to insect and disease problems.
Turf Substitutes
Though a thick, healthy lawn can be a beautiful part of the landscape, if you’re ready for change there are several alternatives to traditional turf. Japanese spurge, English ivy and periwinkle are three ground covers that are good options for an alternative lawn.
Certain ground covers perform well in compacted soils that are unsuitable for a traditional lawn. Areas with little sunlight may not be conducive to growing turf but can be a great environment for perennials. Keep in mind that it may take more time to establish a thick groundcover lawn, and it won’t tolerate heavy foot traffic but once established it will be less maintenance and can stand up to weeds. Here are a few ground cover options to consider:
- Bugleweed (Ajuga spp.)
- Periwinkle (Vinca minor)
- English ivy (Hedera helix)
- Creeping lily-turf (Liriope spicata)
- Lamb’s ear (Stachys byzantina)
- Japanese spurge (Pachysandra terminalis)
Pollinator lawns are designed to provide sustenance for bees and other pollinators by combining turfgrass with flowering ornamentals. Though aesthetically this option lacks the uniformity of a manicured lawn, pollinator lawns require less irrigation, fertilization, mowing and weeding once established. It is important to select turfgrass species that are compatible with the flowering plants and to choose ornamentals that fit the growing conditions.
Here are some plants to consider for a pollinator lawn:
- Dutch white clover (Trifolium repens)
- Self-heal (Prunella vulagris spp. lanceolata)
- Creeping thyme (Thymus praecox spp. arcticus)
- Common violets (Viola sororia)
- Dandelions
When selecting a turf substitute beware of invasive growth habits. Lily of the valley and goutweed are two groundcovers that can be problematic if not managed.
