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Considerations for Edging Flower Beds

This article was originally published on April 27, 2009 and expired on July 15, 2009. It is provided here for archival purposes and may contain dated information.

One of the challenges in taking care of perennial and annual flower beds is maintaining an attractive edge that transitions well with surrounding turf areas. Planting beds typically have loose, fertile soils and exposed, bare edges in which spreading turfgrasses as well as weeds can colonize.

The frequency of edging required to maintain beds is related to the type of grass in the lawn. Tall fescue and perennial ryegrass are bunch grasses that do not spread rapidly and are easy to control. Bluegrass spreads with short underground rhizomes that can encroach gradually into beds. It tends to spread most in the cool weather of spring and late fall when it grows the fastest, so two to three edging operations per season may be adequate.

The most difficult edging challenge is with lawns that contain rapidly spreading warm season grasses, zoysia grass and bermuda grass. Both spread by means of rhizomes, and also above-ground stolons that help form the dense turf these grasses are noted for. Zoysia grass is slower spreading, while Bermuda grass can move quite rapidly and will need multiple edging during the summer growing season.

Managing bed edges can involve one or a combination of several approaches. These include mechanical control, physical barriers, and chemical control.

Mechanical control involves using a broad-bladed spade, hoe, edging knife or perhaps a power edger or weed eater to cut out turfgrass and weeds that establish on the edge of the bed. Hand-pulling is also an effective approach. Mechanical edging provides a manicured appearance, and eliminates risk of using chemicals. It may need to be done several times through the season. Mulching beds makes it easier to pull weeds.

If mechanical edging of invading grasses becomes difficult, physical barriers may be a good solution. These may be any one of several landscape materials. Mulch is a barrier to weed germination, though weed seeds blowing in can germinate in degraded mulch. Structural edging can be made from wood, plastic, metal, concrete, or other items. Selection depends on availability, cost, and personal preference. Continuous edging is best, with few breaks to limit the sites where grass can creep through. Edging set six inches or more deep will be effective in blocking the intrusion of warm season grass rhizomes. More shallow edging is adequate when clump grasses form the lawn. If materials such as brick or stone are used, a footing should be formed beneath, and mortar used to make the edging continuous, stable and deep enough. If the edging is not tall enough, warm season grasses can run over the top with stolon growth.

The third option is chemical edging. This method involves the use of a non-selective herbicide such as glyphosate (ex. RoundupTM). Non-selective herbicides are easy to use, but will kill desirable vegetation as well. They must be sprayed carefully along the bed edge. This is best done on a still morning or evening, using a coarse spray setting that limits drift on desirable plants or grass. Chemical control works well in combination with physical barriers to keep installed edging neat and clean. Pre-emergent herbicides such as PreenTM can help prevent weeds from sprouting in perennial and annual beds. However these herbicides will also affect newly seeded annuals as well as weeds, and they will not stop spreading grasses.

Keeping beds tidy through the growing season is one of the many horticultural challenges in the landscape. By using one or a combination of mechanical methods, physical barriers and chemical control, encroaching grasses and weeds can be managed effectively.

Source: Anthony Bratsch, Extension Educator, Horticulture (Serving East-Central and Southeastern Illinois), bratsch@illinois.edu

Pull date: July 15, 2009

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