To keep a dense symmetrical shape and trigger denser branching, prune lightly but frequently during the growing season. Don’t let it get unruly—it’s better to take off a centimeter or so rather than several centimeters at a time. Plants with large leaves, such as bay, sage, and scented geranium, should be cut back to a leaf node. Those with small leaves, such as rosemary and lavender, can be lightly sheared.
Fertilize during active growth—in spring and summer—every two weeks at half the recommended strength with a balanced fertilizer such as 10-10-10. Herbs need less frequent feeding; about every six weeks is fine.
Mulch—use objects such as terracotta beads, small shells, polished pebbles or gravel—retains moisture and adds an attractive finishing touch, but keep it away from the stem of the plant. Rotate pots every few days to encourage uniform growth.
Small-leafed shrubby plants make the best candidates for topiary. All the examples listed here, except for the boxwood, sage, and lavender, can be overwintered indoors in a sunny window in Zones 5 and lower. Boxwood, lavender, and sage may be overwintered outdoors in Zones 6 and higher in large, double-walled containers in a spot sheltered from the wind and direct sun.
Boxwood (Buxus spp. and CVS.)
Sweet bay (Laurus nobilis)
Lavender (Lavendula spp. and CVS.)
Greek myrtle (Myrtus communis)
Scented geranium (Pelargonium hybrids)
Rosemary (Rosmarinus officinalis)
Sage (Salvia officinalis)
Santolina (Santolina chamaecyparissus)
Coleus (Solenostemon CVS.)
Germander (Teucrium fruticans)