Gadenin日本語Get the appBuds are made in summer, on wood you must not cut
The flowers that open next spring are already being formed within about eight weeks of this spring's flowers fading. Through the second half of summer the plant packs those embryonic buds into the tips of the current year's woody growth, where they sit through autumn and winter as fat, rounded buds on bare stems, waiting for warmth. This one fact explains nearly everything about how tree peonies behave.
It means anything that removes the tips of the wood removes next year's flowers. It means a summer of drought or starvation shows up as a poor spring nine months later. It means a hard frost after the buds have started to swell destroys blooms that were built the previous year and cannot be replaced. And it means the plant cannot compensate: unlike a rose, it will not simply flower again on new growth.
In late winter you can count next spring's display. Rounded, plump buds along the upper wood are flower buds; flat, pointed, narrow buds pressed close to the stem are leaf buds. Counting the round ones in late winter tells you what to expect and, more usefully, tells you which of the causes below applies when the count is low.
A tree peony bought in flower usually flowers well the following year on buds the nursery grew, then disappoints in year two or three while it settles. That dip is normal and is not a sign of failure.
The five reasons a plant does not flower
Age and settling come first. A young grafted plant needs three to five years in the ground before it flowers freely, and a plant recently moved will sulk for two or three. Nothing you do speeds this up; feeding a young plant hard makes leafy growth, not flowers.
Pruning is the next most common cause, and the most avoidable. Cutting the stems back in autumn or late winter, as you would a herbaceous peony or a summer flowering shrub, removes every flower bud on the plant. A tree peony cut to the ground will regrow woody stems over two or three years and flower again eventually, but that year and usually the next are lost.
Then shade, frost and the graft. Less than about half a day of sun gives leggy growth and few buds. A late frost on swelling buds, especially on a plant in a frost pocket or against an east wall that thaws it too quickly at sunrise, blackens buds that were perfectly formed. And a plant whose union was never buried deep enough will decline once the nurse root exhausts itself, dropping bud count year on year while the foliage still looks passable.
| What you see | Likely cause | What to do |
|---|---|---|
| No buds at all, plant under five years old | Still establishing | Nothing; feed lightly and wait, do not move it |
| No buds after cutting the stems back | Pruned off last summer's buds | Never cut old wood again; expect two years to recover |
| Leggy growth, few buds, dark position | Too much shade | Thin overhanging branches or accept a light display |
| Buds formed then blackened and dry in spring | Late frost on swelling buds | Row cover on frost nights; move plants out of frost pockets |
| Bud count falling year on year, plant mature | Graft union too shallow, nurse root failing | Lift in early autumn and reset with the union 4 to 6 in (10 to 15 cm) deep |
| Masses of leaf, almost no flower | Too much nitrogen | Switch to a balanced or high potassium feed, stop by midsummer |
| Buds rot and go brown with gray fuzz | Botrytis in the buds | Cut affected shoots out, improve airflow, clear all debris |
Protecting buds through late frost
The plant itself is thoroughly hardy; the swelling buds are not. Once buds have begun to fatten and show color, a night below about 28F (minus 2C) can kill them outright, and a clear, still, radiation frost does more harm than a windy cold snap. The damage shows within a few days: the bud browns, softens and dries in place rather than opening.
Cover the plant with row cover on nights when frost is forecast after the buds have started to move, and take it off in the morning so air can circulate. Two layers of row cover are better than one heavy sheet, and it must not be left in place through warm days, which traps moisture around the buds and invites botrytis.
Position beats protection. Avoid frost pockets at the bottom of a slope and avoid full east exposure, where morning sun thaws frozen buds too fast and ruptures the tissue. A north or west facing aspect with a wall behind, warming later in the day, loses fewer buds in a bad spring than a sunnier but more exposed spot.
- Count the round buds in late winter Walk the plant with a notebook while it is bare. Round and plump means flower, flat and pointed means leaf. This is your forecast for the season and your baseline for next year.
- Row cover on forecast frost nights once buds swell Drape row cover loosely over the whole shrub in the evening and remove it in the morning. Do not use plastic sheeting; it condenses and rots the buds.
- Leave every scrap of old wood alone Do not shorten stems, tidy tips or cut back for shape. Everything you remove from the upper wood is a flower you will not see.
- Feed within two weeks of the last flower The plant sets next year's buds immediately after flowering. A balanced feed and steady moisture through that window is what determines the bud count.
- Keep the plant watered through late summer Drought while buds are forming reduces both the number and the size of next spring's flowers. This is the least visible and most costly kind of neglect.
Bud blast, and flowers that open badly
Buds that form, reach pea or marble size and then stop, brown and stay closed are described as blasted. On tree peonies the usual causes are frost, drought during formation the previous summer, or botrytis entering the bud in wet spring weather. Frosted buds are dry and papery; botrytis buds are soft, brown and often carry a gray dust. Cut blasted buds off either way, taking the shoot back to healthy wood, and do not compost them.
Flowers that open lopsided, with a mass of petals on one side, usually mean the bud was chilled on one side during formation or the shoot was damaged. It is cosmetic and does not repeat. Flowers that bleach almost white within two days are getting too much direct afternoon sun, which shortens their life dramatically; the plant is fine but the position is bright.
A plant that produces a handful of enormous flowers rather than many medium ones is not doing anything wrong. Some plants naturally carry fewer, larger blooms, and a well fed mature shrub will still only ever carry one flower per current season shoot. Bud count, not flower size, is the number worth tracking.
The record that solves the flowering question
Count the flower buds in late winter every year and write the number down beside the year. A single count means nothing; three years of counts tell you instantly whether the plant is building, holding steady or declining, and declining is the only pattern that needs action. It also separates a bad spring from a bad plant, because frost damage shows as buds that formed and then died, while a shallow graft shows as buds that never formed at all.
Note the date the buds first showed color, and the lowest overnight temperature in the week that followed. After two or three years you will know how early your plant wakes relative to your last frosts, and whether row cover is a routine job or an occasional one.
Record the date the last flower faded, because that starts the eight week window in which next spring's buds are made. Marking that date is the simplest way to make sure the post flowering feed and the late summer watering actually happen, and those two jobs move the bud count more than anything else you can do.