URBANA, Ill. – Spring is usually considered the best time to divide perennials, but there are some that you should only divide in fall and others that can be divided either spring or fall, according to a University of Illinois Extension horticulture educator.
“Most perennials need to be divided every few years, usually every 3-5 years, as they grow and become overcrowded,” Kari Houle explains. “Dividing perennials can help increase blooms, decrease crowding and stress, and – best of all – add more of your favorite plants throughout your garden.”
Houle mentions that peonies are ones that should only be divided in the fall and only if needed. More often than not, peonies don’t need dividing except if you want more of a specific variety.
“If you do dig up and divide your peonies, make sure they have 3-5 ‘eyes,’ which are what will become individual stems next year. Less than that, and it may take a few years after division and transplanting for your peony to flower again,” Houle says.
As always make sure that the location you are planting into is suitable for the plants, “Right plant, right place,” Houle says.
She adds, “If the ground is dry, make sure to water thoroughly a few days prior to digging and dividing. That will make the process easier and less stressful on the plants.”
Divisions and transplants should be replanted immediately to give them time to establish prior to the arrival of winter weather. When dividing plants, make sure they are healthy, and discard any dead sections. Depending on the size of the plant, they can usually be divided into 3 to 5 new clumps, although it is important to make sure that there is enough plant in the clump to survive.
“There are some plants that should only be divided in the spring, as they need a longer season to establish. When in doubt, contact your local extension office to double check,” Houle states.
Perennials that can be divided in the fall include:
- Achillea – Yarrow
- Aconitum napeullus – Monkshood
- Alchemilla mollis – Lady’s mantle
- Asarum europaeum – European ginger
- Asarum canadense – Wild ginger
- Aster frikartii – Aster
- Aubrieta deltoidea – False rock cress
- Aurinia saxatilis – Basket-of-gold
- Campanula persicifolia – Bellflower
- Centaurea montana – Perennial bachelor’s button
- Heuchera sp. – Coral bells
- Hosta sp. – Hosta