Dividing mature peony plants is the traditional method of propagation and an excellent way to expand your collection, share plants with friends, or rejuvenate an ageing clump that has become crowded. While peonies are famously long-lived and generally prefer not to be disturbed, there are times when division is beneficial or necessary.

This guide walks you through the entire process, from knowing when division is appropriate to ensuring your new divisions establish successfully.

When to Consider Dividing Peonies

Unlike many perennials that benefit from regular division, peonies actually perform best when left undisturbed. However, there are several valid reasons to divide:

• Sharing: You want to give divisions to friends or family
• Propagation: You want to increase your stock of a particular variety
• Decline: An old clump is producing fewer blooms than it used to
• Relocation: You're moving house and want to take your peonies
• Overcrowding: The clump has become so large it's crowding other plants

Best Time for Division

Timing is critical when dividing peonies. The optimal window in Australia is autumn, typically from late March through May, depending on your region. At this time:

• The plant has finished its active growth
• Foliage has died back (or can be cut back)
• Eyes for next year's growth are visible on the crown
• Soil is still warm enough for root development
• Cooler temperatures reduce transplant stress

Tools and Materials Needed

• Sharp spade or garden fork
• Sharp, clean knife or pruning saw for tough roots
• Bucket of water or hose
• Fungicide powder (optional but recommended)
• Labels for divisions
• Amended soil for replanting
• Mulch

Step-by-Step Division Process

Step 1: Prepare the New Planting Sites

Before you dig up the mother plant, have your new planting locations ready. Prepare holes 45cm wide and 30cm deep with amended soil. This reduces the time roots are exposed to air.

Step 2: Cut Back Foliage

If foliage hasn't died back naturally, cut stems to about 5cm above ground level. This makes the plant easier to handle and reduces water loss.

Step 3: Dig Up the Clump

Use a spade or garden fork to dig around the plant in a circle, about 30-40cm from the crown. Work your tool underneath the root ball from multiple angles, then lever the entire clump out of the ground. Be prepared; mature peony clumps can be surprisingly large and heavy.

Step 4: Wash the Roots

Gently wash soil from the roots using a hose or bucket of water. This allows you to see the root structure clearly and identify the eyes (growth buds) and natural division points.

Step 5: Divide the Clump

Look for natural division points where the clump separates relatively easily. Using a sharp knife or pruning saw, cut the clump into sections, ensuring each division has:

• At least 3-5 eyes (growth buds)
• Adequate root system (several healthy roots)
• A portion of the crown

Cut cleanly; ragged cuts are more susceptible to disease. It's better to have fewer, larger divisions than many small ones.

Step 6: Treat Cut Surfaces

Allow cut surfaces to dry for an hour or two, then dust with fungicide powder if available. This helps prevent disease entry through the wounds.

Step 7: Plant the Divisions

Plant each division in its prepared site at the correct depth. This is crucial: eyes should be no more than 3-5cm below the soil surface. Create a small mound in the centre of the planting hole, spread roots over it, and backfill with amended soil.

Step 8: Water and Mulch

Water thoroughly to settle soil around roots and eliminate air pockets. Apply a thin layer of mulch, keeping it away from the crown.

Transplanting Without Division

If you need to move a peony without dividing it, the process is similar but simpler. Dig up the entire clump with as much root ball intact as possible and replant at the same depth in its new location. This is less stressful for the plant than division but still involves recovery time.

Caring for New Divisions

Divisions require extra attention in their first year:

• Water regularly during the first growing season
• Don't fertilise heavily in the first year
• Consider removing any flower buds that form in year one to direct energy to roots
• Provide winter mulch in very cold regions (remove in spring)
• Be patient; it's normal for divisions to produce limited growth initially

What to Do with the Original Site

After removing a mature peony, the original site has been depleted of nutrients and may harbour disease organisms. If you want to plant another peony in the same location:

• Remove old soil to a depth of 45cm
• Replace with fresh, amended soil
• Wait one season before replanting if possible
• Alternatively, choose a new location entirely

Common Mistakes to Avoid

• Dividing too small: Divisions with fewer than 3 eyes struggle to establish
• Wrong timing: Dividing in spring or summer causes significant setback
• Planting too deep: Eyes more than 5cm deep may not bloom for years, if ever
• Insufficient root: Each division needs adequate root mass
• Letting roots dry: Keep roots moist during the division process
• Rough cutting: Ragged cuts invite disease; use sharp tools

Sharing Divisions

Peony divisions make wonderful gifts for gardening friends. To prepare divisions for sharing:

• Wrap roots in damp newspaper or hessian
• Place in a plastic bag with holes for air circulation
• Label with variety name if known
• Include planting instructions (especially depth!)
• Share within a few days; don't store long-term

Dividing peonies takes some courage; cutting into a beloved, long-established plant feels drastic. But done correctly at the right time, division gives you multiple plants from one, each capable of living and blooming for decades. The temporary setback is well worth the long-term reward of expanding your peony collection or sharing these magnificent flowers with others.