Are iris taking over the garden?
Do the daylilies block daylight?
Have huge hostas crowded out their neighbors?
Fall is the time to conquer the jungle that the garden has become. Dividing perennials is a great way to rejuvenate older plants and thin clump-forming varieties. Tackle this every three to six years to control plant size, invigorate growth, promote blooms, and multiply the number of plants in your garden.
An age-old rule of thumb is to split apart spring- and summer-blooming perennials before the first frost. Fall bloomers are best divided in the spring so that they can devote their energy to growing roots and leaves through spring and summer to be well established for their fall show.
Before dividing, water the mother plant well for a day or two before you dig it up, and if you can, wait for a cloudy day to do the actual digging – hot, sunny weather stresses plants – and the digger. Then follow these simple steps and you’ll be rewarded with more vigorous plants and extras to share with friends or add to your garden.
Rake away and discard any old mulch. Set a spade or shovel 6 to 12 inches from the center of the plant and push it down vertically into the soil. Work the shovel around the plant until you’ve formed a circle. Now slip the shovel blade under the root ball and pop it out of the ground.
Pluck out thin or weak stems then gently separate the remaining healthy ones into clumps of three to five shoots. That number helps ensure that the plant will recover quickly after being divided. If the center looks dead compared with the outside edges, cut it away with a soil knife and divide and replant the healthy outside edges.
For plants that can’t easily be pulled apart by hand, place a soil knife between the separated stems and saw straight down through the roots that form the crown. Continue cutting all the way through the root ball. For larger, heavier root balls, use two garden forks placed back-to-back to pierce the center of the crown. Push the forks apart until the clumps separate
Gently tease the roots out of the bottom and sides of each new clump with your fingers. Now dig the holes; they should be 1 to 2 inches shallower and 6 to 9 inches wider than the teased root ball. Plant each root ball, and backfill with soil mixed with a root-promoting fertilizer, watering as you go. Water every two or three days for the next couple of weeks to get them established. Apply an inch or so of fresh mulch to protect the new plants over the winter.
Before replanting, take the opportunity to replenish the garden with nourishing compost. Use either homemade compost or commercially bagged to enrich tired garden soil and encourage strong root growth over the winter. Come spring, you’ll be rewarded for this extra work with vigorous, healthy plants.
Turn this autumn task into a party. Invite gardening friends to pull on their gloves, grab empty pots from their shed and join in – entice them with the promise that those empty pots will go home with plants for their garden.