Many common groundcovers may become overgrown in time, with thick, tangled growth that may interfere with irrigation, provide habitat for rodents, or even become a fire hazard. A periodic mowing of these groundcovers helps to keep them vigorous, neat and healthy. Mowing checks excessive growth, thins out thick, unwanted stems, and can even help to rejuvenate old, less vigorous groundcovers.

Vigorously growing species with herbaceous or fibrous stems, like trailing lantana, periwinkle, and garden verbena respond best from mowing because they recover quickly, usually within one to two months. The stems of such groundcovers are fairly easy to mow and collect, or fall to the ground leaving no unsightly debris. For example, studies on groundcover mowing show that mowing has only a negligible effect on the overall quality of trailing African daisy, coyote bush and lantana, yet kept their growth in check.

Not all groundcovers are suitable for mowing, however. Non-vigorous groundcovers recover slowly, leaving the area unsightly and prone to weed invasion. If you allow certain groundcovers to develop succulent, fleshy or woody stems before their first mowing, like some of the ice plants and prostrate rosemary, they usually become too difficult to mow. Mowing crushes succulent, fleshy growth while large stems of woody species clog or jam the mower. If you want to successfully mow woody species, like ceanothus, coyote bush, prostrate junipers and rosemary, start mowing them at an early age, just after they become established, and continue mowing regularly.

Timing of mowing is important to ensure that the plants will recover rapidly, with little weed invasion. For the early spring flowering groundcovers, like bugle weed, periwinkle, pink ice plant and trailing African daisy, mow soon after flowering (summer mowing). For the later summer flowering types, like creeping rose, Hall’s honeysuckle, and trailing lantana, mow just when new growth begins in spring (spring mowing).

It’s best to start a regular mowing program on newly established groundcovers. Plants respond well to mowing when they are young and growing vigorously. Waiting too long to mow established groundcovers, even those well suited to mowing, can be difficult and may give poor results, especially if thick growth has built up.

You can use an ordinary turf-type rotary mower for groundcovers with thin, non-fibrous stems like trailing lantana and garden verbena. You will need to use a larger, commercial, flail-type mower on groundcovers with thicker, fibrous stems. The larger mower will be especially necessary on first mowed, old plantings. However, once mowed, even the thicker stemmed groundcovers can be mowed with an ordinary rotary mower, especially if done regularly.

Mow groundcovers at or just slightly above the branching points on stems, in most cases from four to six inches high. Mowing too low inhibits or slows plant recovery, while mowing too high will not give you the desired results. You may need to do some experimenting to see which height best suits your garden conditions and tastes. In order to help the groundcover recover rapidly, be sure to fertilize and water thoroughly after mowing.