Perennials include all those flowering plants that bloom year after year (with care) such as chrysanthemums, marguerites, or daylilies. Some perennials grow, bloom, and then die back to ground level each year, while others are evergreen and produce new foliage even when they are not blooming. Whatever their growth habit, perennials require some grooming during the year to keep them healthy and good looking. Some may need dividing or transplanting when they begin to look crowded.
Follow these Four Basic Care Techniques
Shear dead flowers from plants (like dianthus or marguerites) when the bloom season is nearly over.
Cut back or remove woody or dying parts of plants (like geraniums or chrysanthemum).
Tip cut to produce new sturdy young plants from old plants (like alyssum or sedums).
Break up or divide to renew crowded masses of daylilies, coral bells, or Shasta daisies.
The illustrations and text on these two pages guide you through these four techniques. Selected plant lists are included with each technique. For a plant not listed, select the grooming technique best suited to the plant.
On some plants the flower stalks can be cut back to a main stem or to ground level right after blooming. The sketch below illustrates how you cut plants like aster, chrysanthemum, delphinium, foxglove, gaillardia, gloriosa daisy, hellebore, iberis, penstemon, phlox, sedum, and yarrow.
Plants that produce new shoots from underground (like asparagus fern, fibrous-rooted begonia, or plumbago) can be cut back to ground level.
Cut old stalks of chrysanthemums to ground level after bloom. New shoots will form at the base, will flower next year.
For geraniums and pelargoniums, cut woody stalks back to a bud or side shoot as shown in the sketch below.
Cut back leggy geraniums to a strong bud or side shoot; new growth will sprout at cut. Trim from spring to fall.
For polyantha primroses, cut off the top half of the old leaves after bloom to force a second bloom period (see sketch below).
Cut the leaves (half way) of polyantha primrose to produce a second bloom. Remaining leaves will have more light.
Use hedge shears or grass clippers to cut off faded blooms and not more than an inch of foliage. Leave as much leaf surface as possible since the plants may not sprout new growth from bare twigs. Shear such plants as alyssum, chamomile, dianthus, gazania, marguerite, phlox, rosemary, thyme, or any other evergreen with dense bloom.
Many perennials quickly form new roots if you break off healthy shoots and stick the broken end into moist sand or prepared sand and soil mix. Some perennials that root easily are alyssum, arabis, aubrieta, bergenia, chrysanthemum, delphinium, dianthus, geranium, iberis, pelargonium, and sedum.
Remove healthy shoots from crowded arabis. Have new pot filled with soil mix ready for cutting.
Poke a hole in soil mix large enough for each cutting. Once in place, gently firm soil around each cutting.
Remove plants when they have grown 2 inches. Good root growth looks like this. Replant to large container.
Some perennials form a dense clump with old growth at the center and young shoots around the edge. You can pry some clumps apart with spading forks, cut them with a knife or hatchet or dig them up and break off the young outside pieces for replanting, then discard the old centerpiece. Plants that can be pried into sections are acanthus, agapanthus, daylily, and kniphofia (called ‘red hot poker’). Plants with dense roots that need cutting apart are asparagus fern, columbine, iberis, Shasta daisy and yarrow. Pull off rooted outside pieces of coral bells, chrysanthemum, and primrose for replanting and discard the woody center.
Use spading forks to pry matted roots of daylily apart. Put separated clumps back in the ground immediately.
Slice dense roots apart with a sharp knife. Set individual clumps in the ground or in separate pots.
Pull apart roots of young coral bells growing at outside edge of old clump that has been dug up. Replant, repot.