Why does my peony not flower?

Planting depth is the answer in most cases and it is the one people find hardest to believe, plus the other five causes and the buds that brown off just before opening.

Difficulty: beginner
Time: 30 min
Read: 5 min

Short answer

A herbaceous peony planted too deep will not flower, and this is the commonest cause by a long way — the growth buds on the crown should sit no more than about 25 to 50mm below the soil surface. The other causes are too much shade, a recent move, a plant that is still too young, congestion, and buds killed by frost or botrytis.

Peonies are extremely long-lived, occasionally outlasting the gardens they were planted in, and they are almost entirely trouble-free once established. The one thing they are fussy about is depth. A peony that produces plenty of healthy foliage and no flowers year after year is nearly always sitting a few centimetres too low in the ground.

What you'll need

Spade and fork
Cane or straight edge to check the level
Compost for mulching (optional)
Ring stake (optional)

Step by step

Check the depth of the growth buds first.Scrape the soil away carefully in autumn or early spring until you find the pink or red growth buds on the crown. On a herbaceous peony they should be no more than about 25 to 50mm below the soil surface. Deeper than that and the plant produces leaves and no flowers.
Raise a peony that is too deep, in autumn.September or October. Lift the whole plant with a fork, taking as much root as you can, and replant with the buds at the correct depth. Lay a cane across the hole to judge the level accurately.
Note that tree peonies are different.A grafted tree peony is planted deep on purpose, with the graft union 100mm or more below the surface, to encourage it to root from above the graft. The shallow rule applies to herbaceous peonies only.
Check whether a mulch has buried it.Years of compost mulching gradually raise the soil level and bury the crown without anyone noticing. This is a very common and completely invisible cause. Mulch around a peony, not over it.
Assess the light.Peonies want full sun or, at most, light shade for part of the day. In a border that has become shaded by a growing shrub or tree they flower less each year and eventually stop.
Allow for recent moving or planting.Peonies resent disturbance and commonly take two or three years to settle and flower after being planted or moved. A plant that has not flowered for one season after a move is behaving normally.
Consider age and size.A young plant, or a small division with only one or two buds, may simply not be big enough yet. Give it time and do not divide it again.
Look for congestion.Very old clumps do eventually decline. Lift and divide in autumn, cutting the crown into pieces with three to five buds each, and replant at the correct depth.
Diagnose buds that form and then fail.Pea-sized buds that brown off and abort are often frost damage or simply an immature plant. Buds that blacken, go soft and rot, with grey mould, are peony wilt — a botrytis infection. Cut affected stems out at ground level, bin them, clear all debris in autumn and improve air movement.
Feed lightly and stop using high nitrogen.A general or high-potash fertiliser in spring and a compost mulch around, not over, the crown. Heavy nitrogen produces lush foliage and fewer flowers.
Support before flowering.Double-flowered peonies become extremely heavy in rain and split the clump open. A ring stake put in during April holds them; a stake pushed in after the collapse does not.

Tips

Ants on peony buds are harmless. They are after the sweet secretions on the buds and they do not damage the plant or affect whether it opens.
Peonies dislike being moved so much that the usual advice is to site one and never touch it again. A well-placed peony can flower for fifty years or more.
Cut peony foliage down to the ground in autumn and bin rather than compost it if there is any sign of peony wilt.
For cutting, pick peonies at the soft marshmallow stage when the bud gives slightly under a squeeze. Picked tight, they may never open.

Common mistakes

Planting the crown too deep — It is the single commonest reason a peony does not flower, and it produces perfectly healthy foliage, which sends people looking for feeding and disease answers instead.
Mulching over the crown year after year — It buries the plant gradually until it stops flowering, with no visible moment of cause. Mulch around it.
Dividing a peony that is simply not flowering — Division sets it back further. Check the depth and the light first; division is for genuinely congested old clumps only.
Assuming ants are the problem — They are irrelevant. Removing them changes nothing about whether the buds open.

If it doesn't work

Healthy foliage every year, no buds at all

Cause: Crown planted or buried too deep — Fix: Lift in autumn and replant with the growth buds 25 to 50mm below the surface.

Fewer flowers each year in a maturing garden

Cause: Increasing shade — Fix: Reduce the shading growth, or move the peony to a sunny position in autumn and expect two or three years to re-establish.

Small buds that brown and dry without opening

Cause: Frost damage or an immature plant — Fix: Usually resolves with age. Fleece in a hard late frost if it recurs.

Stems collapsing with grey fuzzy mould at the base

Cause: Peony wilt, a botrytis infection — Fix: Cut affected stems to ground level and bin them, clear all foliage in autumn, and improve air movement around the plant.

Flowers face down in the mud after rain

Cause: Heavy double flowers with no support — Fix: Fit a ring stake in April, before the plant needs it.

Questions people ask

How deep should a peony be planted?

The growth buds on a herbaceous peony should sit no more than about 25 to 50mm below the soil surface. Deeper than that and it produces leaves without flowers.

How long after planting before a peony flowers?

Often two or three years. They resent disturbance and take time to settle, so a newly planted or recently moved peony that does not flower is behaving normally.

Do ants stop peony buds opening?

No. They are attracted by sweet secretions on the buds and are harmless. The buds open with or without them.

Can I move a peony?

Yes, in autumn, though expect two or three years without flowers afterwards. Replant at the correct shallow depth — this is the moment to fix a plant that was buried too deep.