When to divide perennials:
Except in areas with extremely cold winters (-10 to -20F) the best time to
divide most perennials is in the fall. As a rule of thumb we divide spring and
summer flowering varieties in mid to late autumn (end of September - October here in zone
6) and fall flowering plants in early spring (March). If you do live in an
area where winters are harsh it is best to do all your dividing in early spring.
How to divide perennials:
Division techniques depend upon the type of root system the perennial has.
A plant with a loosely woven root system can usually be gently pulled apart by hand.
Just dig off a portion of the plant with a trowel or spade and using your hands pull apart
good size clumps. When a perennial clump is more tightly bound together with
good size roots you can use two garden forks to divide the clump. Some roots are
harder to divide than others so you may need a good sharp knife or hatchet to aid in your
dividing efforts. Perennials with large fleshy underground stems called rhizomes (such as
Bearded Iris) can be divided by cutting pieces of the root off with your knife. When
cutting the roots with a knife let the roots air dry for a couple of hours to help the
wounds heal before returning them back to the garden.
Pruning and deadheading your perennials:
While most people associate pruning with woody plants such as trees and shrubs
pruning perennials is one of the best ways to keep your garden looking fresh and healthy.
With some very easy techniques you can keep perennials in bloom longer, promote new
growth and control aggressive varieties. One of the most common methods of pruning
is deadheading. This form of pruning is the single most important thing you can do
to maintain a gorgeous garden. Deadheading is simply removing spent flowers from the
plant. This will not only improve the looks of the plant, but encourages the plant to
spend its energy producing flowers instead of seed. One note on deadheading -
you may want to let a few perennials set seed to attract birds and wildlife. The
second form of pruning is cutting back or shearing the entire plant back to leave only
3 or 4 inches above the ground. Cutting back improves the appearance of the
plant and promotes new stockier growth. Most all perennials need to be cut back
immediately after they have finished their bloom cycle. Many plants will recover
quickly from cutting back and flower again later in the season. After cutting back
the plant give it light dose of and organic fertilizer and water thoroughly. New
growth will appear with in days.
Some late blooming perennials such as Asters and Mums need to be cut back at
least once during the summer to promote more compact plants and heavier flowering.
Cut these varieties back to about 4-6 inches sometime in mid June and you will have much
better looking plants in the fall.