When it comes to plants… too much of a good thing is seldom bad! Unless you are a plant and your roots and crown are overcrowded and your neighbors are growing in number!
Everyone loves some wiggle room, so this fall - it’s time to divide to keep your plants happy! But which plants should you divide this autumn and which should wait until spring?
Nature Hills Nursery has the answers for you!
Dividing and Transplanting Perennials
Perennials are wonderful flowering and foliage plants that bring loads of color, vital nectar and pollen-rich flowers for pollinators, long-lasting or long-blooming flowers, and fresh growth throughout the growing season before typically dying back to their roots for the winter. Just to start it all over again next year…a bit bigger.
Most plants will do fine no matter when you get them moved around as long as you are able to give them the care and watering they will need until established. However, when perennials are dormant, they aren’t growing above ground. That means roots can grow below ground as long as the ground isn’t frozen solid. So dividing and transplanting in the autumn allows the roots to establish now and be ready to get growing in the spring like nothing happened.
When a Perennial has been growing in the same location for a few years, it can deplete the soil of nutrients, fill the soil area with dead roots and debris, push soil out away from the inner root clump and away from roots, and generally wear out their welcome in that area.
There Are Many Good Reasons To Divide Your Perennial Plants:
It’s recommended you divide perennials every 3-5 years.
- Keep the plant's health
- Stimulate new growth and better flowering
- Increase air circulation around the plants
- Maintain the size in tight spaces
- Maintain the health of the roots
- Prevents overcrowding
- Break up larger clumps and maintain vigor
- Spread them throughout the garden and repeat them throughout your border
- Share a prized perennial as a gift!
- Create more space for roots to grow and absorb nutrients and water
- Replenish the site with fresh earth, compost, and other amendments
Some Perennials, like Peonies and Rhubarb, have been well-known to grow undisturbed in the garden for 50 or more years! Almost all other perennials though, appreciate being divided and transplanted into an area with increased nutrient access.
Signs When To Divide Your Perennials
Some of the telltale signs it’s time to divide your perennial plants include:
- Reduced or non-existent flowering displays & smaller flowers
- Yellowing leaves for no reason
- Stunted, wimpy, sickly-looking growth
- The center of the clumps is dying out/Bald spots
- The clump is overtaking its area or overtaking other plants
- Excessively leggy growth that needs to be staked when it didn’t in the past
- Plants are getting newly shaded out by larger plants
- Plants are suddenly competing for space
Avoid dividing a plant that is already stressed - like drought, physical damage, etc., but in cases like planted in the wrong location (too shady/too sunny) or the ground has poor drainage or is wet/flooded and the plant is suffocating, by all means, get it moved to a more appropriate location!
It’s also recommended you do not divide or transplant plants while they are flowering.
Avoid dividing or transplanting Perennials with large tap roots or delicate root systems.
Perennials That Are Best Divided In Fall
These Perennials are usually divided in the autumn a few weeks before the ground freezes solid (hard freeze). Preferring to be dormant first so they will remain dormant all winter and work on getting those roots settled under a blanket of snow.
- Allium/Perennial Onion
- Asiatic Lilies (after foliage yellows)
- Bellflower
- Black Eyed Susan
- Bleeding Hearts
- Corydalis
- Foam Flower
- Foamy Bells
- Perennial Geranium/Cranesbill
- Hostas
- Oriental Lily (after foliage yellows)
- Oriental Poppy
- Peony
- Primrose
- Sedum
- Spiderwort
- Tiarella
Trim back any excess leaf matter from the crown and mulch the area with a fresh layer... with a fresh layer of arborist mulch to protect it. Remove these trimmings from the area, especially if those leaves showed any signs of powdery mildew or other fungal issues last growing season.
Perennials That Can Be Divided Spring or Fall
Some Perennials that are just fine with being moved around and divided any time they are dormant in the early spring or late fall.
Transplanting in early spring or fall means no excess heat and sun and typically no drought to contend with, nor do the plants need to focus on actively growing above ground at this time - giving them plenty of time to work on just new root formation.
- Astilbe
- Bergenia
- Blanket Flower
- Catmint/Catnip/Calamint
- Coneflower
- Coreopsis
- Creeping Phlox
- Daisies/Shasta Daisies
- Daylily
- Foxglove
- Gaillardia (Blanket Flower)
- Goat’s Beard
- Hellebores/Helleborus
- Hosta
- Lavender
- Liriope (Lily Turf)
- Lungwort
- Obedient Plant
- Sea Thrift
- Verbena
- Veronica
How To Divide Perennials
Take stock of your Perennial in the ground, clear away leaf litter and mulch. Brushing away as much surface soil as possible to get a good idea of where the root ball extends. You can even use a hose to wash away soil for a clearer view of the roots.
Plan your cuts! Look for clumps that are either already pulling away from the main Mother plant (pups or daughter plants), or just divide them up into 6-12 inch chunks.
Using a sharp, straight, sterilized spade, push it down all around the Perennial root ball, just outside of its reach. Go as deep as you can with each push (usually away from the roots by about 1-2 feet depending on the size and type of perennial). If you are seeing cut roots after removing the shovel, back away a bit and continue.
Using the shovel, spade, or garden fork, start going around the root ball at an angle and gradually begin lifting the entire root ball, or just removing sections and separating it from the area. Work around the entire section, lifting gently until it comes loose.
Pull the root ball or root section out and hose off excess soil for a clear view of the roots.
Once you know how many plants you’ll be breaking the Mother Plant into, dig and prepare the sites for the soon-to-be-divided plants to be transplanted into. Wrapping the exposed Mother Plant’s roots to keep them from drying out or being exposed to the sun.
Using a clean, sharp spade or garden knife, carefully make your cuts from crown to bottom, working around larger roots to keep from disturbing them. You can also use two garden forks, back-to-back, to pull apart the sections. For more delicate/smaller perennials, you can even use your hands to tease the roots apart.
As you separate each section, keep it watered, soaking in a bucket, or wrapped to prevent the roots from drying out or being exposed to the sun.
Transplant Your Divided Perennial Sections
Now you have your plants separated, it’s time to replant them or transplant them into their new homes!
- Perennials, annuals, and vegetable gardens are all plants that benefit from amending the soil to improve the organic matter, improve drainage, and improve the soil these plants will establish into.
- Sprinkle in some Nature Hills Root Booster. If you are moving the Perennial from the area entirely, fill the hole in with topsoil.
- Plant a section of the newly divided Perennial, water it in very well, and ensure its roots are planted at the same depth they were previously - no deeper and no higher. Then backfill with fresh topsoil, and tamp down, and water completely saturating the root area.
- Repeat with the remaining sections you’ve divided!
- Top-dress all the new plants with a 3-4 inch deep layer of arborist mulch and/or compost
- Check them daily and water deeply using the Finger Test as needed. Those disturbed roots will take a few days to get over the shock.
Multiply Your Garden Perennials!
Like a reward for all the pampering and care you gave them, dividing your Perennials is rewarding! Your plant babies can often be divided into 2, 3, 4, or more new plants for you to share and spread the love!
How many plantlets you divide your main clump into is also determined by how long you want to wait for that new plant to grow back to its mature clump size. If you have the patience and want to turn that one large Daylily clump into a new edging row, you can do it - but it will take several years for those transplants to fill in.
This form of propagation keeps your Perennial healthy and your garden brimming! So get out there this fall and see which of your plants need some wiggle room!
Don’t have root for your divisions? Give them away to an eager friend, family member, or neighbor! Schools, Churches, and Retirement homes are always great places to gift your excess divided plants too! Otherwise, a local plant club or Master Gardener in your area will be happy to take them off your hands.
Happy Planting!
