Dividing Perennials

Fall Gardening Tasks

Fragrant Paperwhite narcissus will bloom indoors by Thanksgiving if planted now in rocks and water. Plant pansies, snapdragons, stock, calendulas, and primroses now to replace summer annuals. Plant lawns now to have them ready for next summer enjoyment—ask at your nursery for the best grass seed for your situation. Garlic sets can be planted now for an easy crop that you can harvest next spring. Choose from hard-neck, soft-neck, or Elephant garlic varieties now available.

Compost your leaves as they fall—don’t burn them! Leaves make wonderful compost that breaks down into rich humus by next summer.

Dividing Perennials

Fall is a great time to rejuvenate the perennial border by dividing old clumps of perennials to keep them vigorous and blooming freely. In general, summer bloomers should be divided in the fall, and fall bloomers divided in the spring. Grasses and bamboo should be divided in early spring just as growth begins. Most perennials should be divided every three to five years, but some, like peonies, are best left alone, as it will take them several years to begin blooming again.

Perennials need dividing when:

• The flowers are smaller than normal
• The centers of the clumps are hollow and dead
• The bottom foliage is sparse and poor

Plants that are growing and blooming well should be left alone unless more plants are wanted.

How to Divide Perennials

Water plants thoroughly a day or two before you plan to divide them. Prepare the area where you plan to put your new divisions before you lift the parent plant. Prune the stems and foliage to 6 inches from the ground to make the job easier and to cut down on moisture loss.

• Dig down on all four sides of the plant, about 4 to 6 inches away from the plant.
• Pry underneath with a spading fork and lift the whole clump.
• Shake or hose off loose soil and remove dead leaves and stems to loosen tangled root balls.

Types of Perennial Root Systems

• Spreading root systems (asters, bee balm, lamb’s ear, Black-eyed Susans): Often crowd out their own centers and can usually be pulled apart by hand or cut apart with shears or a knife. Discard the old woody center and replant the young, healthy pieces.
• Clumping perennials (astilbes, hostas, daylilies): Grow toward the outside of the clump, creating new growing points. Many have thick fleshy roots and may require cutting to separate. Keep at least one developing eye or bud with each division.
• Bearded iris: Grow from rhizomes and need dividing when they stop blooming well. Discard old sections and keep divisions with one fan of leaves, trimmed back halfway. Replant with the top of the rhizome just beneath the soil surface.
• Tough, vigorous root systems (agapanthus, red-hot pokers, ornamental grasses): May require a shovel or saw to divide. Hose off soil to make roots easier to work with.

After Dividing

Plant the divided sections immediately in the garden or in containers. Replant divisions at the same depth they were originally. Firm soil around the roots to eliminate air pockets and water well after planting.

Fall is the best time to divide most perennials because air temperatures are cool and soil temperatures are warm. Take advantage of the mild fall weather to revitalize your perennials.