Dividing Perennials

Saturday, September 08, 2007 03:45 AM

September is the time of year when the outdoor gardening is coming to an end. I find it can be a busy time of year because you want to get everything ready before the winter weather sets in.

If you have perennials that need to be divided or moved there is still time to do this in the next couple of weeks. Perennials such as iris, lilies and peonies are best divided in the fall, whereas the others can be left until spring. You should divide perennials every few years to rejuvenate the plant. You can tell when they need to be divided by their appearance and how well they bloomed. When the plant becomes overcrowded it will produce smaller and less blooms than in previous years. Also on plants such as iris the center of the plant dies out, resulting in an outer ring of growth with no plants in the middle.

Bearded irises should be divided every 3-4 years whereas the Siberian irises only need to be transplanted every 8-10 years. To divide an iris you first cut back the foliage by half and then with a sharp spade dig around the
perimeter of the plants roots. Divide the plant into half, thirds etc. depending on the size of the plant and then replant into new areas of the yard. Sprinkle some bonemeal in the hole before placing the plant in the hole and then fill the hole with soil finishing off by giving the plant a good drink of water.

Peonies are slow growing and take 4-5 years before reaching their mature size and rarely outgrow their spot but if you want to divide the plant to get more plants or move the plant into another location this is the time of year to do this. To divide a peony you should first cut back the foliage by half so that the plant can put its energy into producing new roots once its been moved. Next you want to dig around the plants roots so that you get a nice sized root ball with as much soil around the roots as possible. To divide it, use a sharp spade and split the plant into 2, 3, 4 pieces depending on the size of the plant. Peonies are grown from a tuber and so when you divide the plant you want to make sure that each new piece has at least 3-4 buds for best results. After the plant has been divided replant it the split new plants in their permanent spots. Always sprinkle a handful of bonemeal in the bottom of the hole before planting the plant and then pack the soil firmly around the plant finishing off by watering it in well.

Lilies should be divided every 4-5 years, because if they aren’t they will produce thin stalks which do not produce flowers. They are grown from bulbs and the bulbs produce bulblets that need to be removed from the main bulb.
To divide lilies you should cut back half of the foliage and then carefully dig up the bulbs. Divide them by pulling them apart and separating the bulbets from the main bulbs. Replant the main bulbs with their live roots intact immediately as you do not want them to dry out which will cause the bulb to die. You can either toss out the smaller bulblets or replant them as well, but the small bulblets will not produce a flower for the first couple
of years. When replanting the bulb toss a handful of bonemeal in the hole and plant the bulb at the same depth as before which tends to be 3 times the depth of the bulb. After you have buried the bulb with soil, water it in well. Lilies need to be planted in a rich, fertile soil that is well drained.

The weather lately has been good for transplanting because of all the moisture we’ve been receiving but if it does become dry you need to remember to keep all perennials, shrubs, tree, and bulbs well-watered before they head into the winter.

-Jos

Jos Van Hage owns two Art Knapp Garden Centres in the Prince George area: