Pachysandra & Weeds
Pachysandra is a groundcover with dark glossy green leaves, and white blossoms that appear in springtime (May). It has become a popular evergreen groundcover for its thick mat-like growth habit, and also because it grows best in shady areas of the landscape--places where other plants cannot grow. Before pachysandra is established weeds can be a problem in the groundcover bed. However, once established pachysandra’s thick mat keeps weeds down.
Pachysandra terminalis is a member of the Buxaceae or Box family. Other common names are: Japanese pachysandra, Japanese spurge, or spurge. This herbaceous perennial evergreen is medium in size, growing from 8 to 10 inches in height, and spreading by basal shoots. It is a slow grower, and it takes approximately three years before it forms its dense mat-like cover. It is hardy in zones 5 to 8.
Planting and Mulching
Pachysandra should be planted from 6 to 12 inches apart. Since pachysandra is slow growing it will take time to spread and cover the area that it has been planted in. To keep weeds down you should apply a 2- to 4-inch layer of mulch to the groundcover bed. Since pachysandra grows well in organically rich well-drained soil wood chips would be an excellent choice for the mulch material. The mulch will help to control weeds, and it will also keep moisture in the soil.
When Weeds Appear
When broadleaf weeds appear within the pachysandra bed the only safe way to get rid of them is to remove the weeds by hand. Mulch will keep most of the weeds out and you will only have a few weeds. However, if you do not mulch, and you do not weed as soon as the weeds appear, the weeds will get out of control.
Broadleaf Weed Herbicides
Greg Stack of the University of Illinois Extension Service recommends painting the offending weeds with Roundup to control growth. This will not do damage to the pachysandra if you do it carefully. It might be safer, however, to pull out the weeds by hand.
Mature Pachysandra Bed and Weeds
An established/mature pachysandra bed is extremely dense, and weeds will not be a problem. Weeds are only a problem when you are first establishing the groundcover. The plants will grow together and you will no longer need to mulch to keep the weeds down. Fall leaves that find their way into the groundcover bed (in between plants) will become natural mulch, decomposing and adding organic material to the soil.