Some ground covers do better if mowed about once a year. This rejuvenates new growth and prevents an accumulation of dead stems and litter. Mowing, or any method of cutting back old growth, is very important to the appearance of a ground cover. When litter accumulates or the foliage loses its fresh appearance it is time to clip off the old growth. Generally, the best time to trim is just prior to the plant’s normal growth cycle. This is in spring for most ground covers, just as the weather begins to warm.
Mowing enhances the beauty of carpeting plants such as wintercreeper (Euonymus), Japanese spurge (Pachysandra terminalis), moss pink (Phlox subulata), and bugleweed (Ajuga). A rotary mower adjusted to the required height and equipped with a bag for collecting the clipping debris is necessary.
Trimming Slopes
Mowing an out-of-the-way area or a steep slope can be difficult or impossible. However, the nylon-line trimmers designed for edging and trimming can be used to some extent for controlling ground covers in difficult terrain. Depending on the toughness of the foliage and the power of the trimmer, this tool can do the job when nothing else can (aside from tedious hand shearing). Keep the trimmer an equal distance from the ground to maintain a level cut.
Pruning
Some ground covers, especially the taller-growing, vining types, can be improved by pruning rather than by mowing or trimming. Using pruning shears on such plants as Oregon grape (Mahonia aquifolium) and wintergreen (Gaultheria) helps to maintain compactness and the desired dense growth.