Divide and Conquer
Divide and Conquer
Beat the high cost of perennials by dividing your own. Former USU Extension Horticulturist, Maggie Wolf, says perennials, although not maintenance free, are great plants for home landscapes. Year after year, these plants grow back, usually with more vigor and flower power. But as the plant’s root system expands, roots may begin crowding each other, reducing vigor and flowering. Most perennials tolerate or grow even better when divided once every few years. Division can help save homeowners’ money, providing new, “free” plants to fill in flower beds.
Perennials cost more for growers to produce; they grow slower from seed than annuals and won’t usually flower until the second year. When starting their landscapes, thrifty homeowners could invest in a few perennials and fill in the garden gaps with less expensive annuals. After a couple of years, the perennials will be large enough to divide and distribute around the garden. Eventually, the homeowner won’t need to buy any more plants at all.
Dividing perennials is not especially difficult, but you’ll have best success when your timing is right. For most of Utah, autumn is the time to divide summer-blooming perennials such as chrysanthemum, Lamb’s ear, coneflower, red-hot poker, sedums, yarrow, coreopsis, gaillardia, and ornamental grasses.
Before you begin dividing your perennials, make sure the soil is completely drained and not soggy. Working soil that is too wet ruins soil structure and retards root re-growth. Tight, clay soils drain slowly and will also form the hardest clods if you dig while the soil is too wet.
The first step in dividing perennials is to lift a clump of the plant out of the ground using a spading fork or a spade. If the clump is very large, you may need to dig it in sections. You won’t need to dig too deeply; most of the root system will be in the upper six to eight inches. Turn the clump on its side, preferably on a solid surface like a stepping stone or sidewalk.
If you have two garden forks, you can pry the clump apart, pierce the clump with the forks back to back, then pull the fork handles apart to pry open the clump. Or, use a pruning saw or old serrated knife to start loosening the clump.
Pull the plant apart, using tools or hands. Depending on how many new plants you would like, and how large you want your new plants to be, leave the pieces larger or smaller. New plants should have about 3 to 5 crowns with roots attached.
As you proceed, protect roots from drying out. Newly divided parts should be planted in their new site as soon as possible. Or, the pieces can be potted up in bedding plant containers until spring. After transplanting to the new site or container, water the plants thoroughly. Don’t fertilize until the root system has recuperated, at least one month. Fertilizer promotes top growth that can’t be supported by a damaged root system. Some perennials will need to recuperate one or two seasons before they’ll bloom again.
Potted plants should be sunk into a shallow hole, then mulched heavily. Once dormant, add more mulch to cover the plants a few inches. This will insulate the root systems from very low temperature, so that they won’t freeze over winter. Check them in mid-winter to be sure the potting media isn’t too dry. If so, water them and re-apply the mulch.