Gadenin日本語Get the appLate winter: count the buds and cut the dead wood
While the plant is still bare, walk it and count the flower buds: round and plump along the upper wood, as opposed to the flat, pointed leaf buds pressed against the stem. That count is your forecast for the season and your comparison point for next year. It takes five minutes and it is the most informative thing you do all year.
This is also the only time you cut anything structural. Scratch test doubtful stems and remove the genuinely dead ones back to live wood, take out crossing or rubbing branches, and thin a few congested inner twigs on a mature plant for airflow. Disinfect the blade between cuts. Everything else stays, including every healthy tip.
Rake the ground under the plant clean of any remaining leaves and old mulch, then top up with 2 in (5 cm) of fresh compost kept a hand's width off the stems. Scrape the soil back at the base while you are there and check for soft, ferny suckers coming from below the graft union.
If the plant looks entirely dead in late winter, do not cut it down on that assumption. Scratch the bark. Tree peonies leaf out later than most shrubs and bare gray stems in cold weather are completely normal.
Spring: feed, support, and protect the buds
As the red new shoots push and the buds begin to swell, scatter a balanced granular feed over the root area and scratch it in. Once the new growth is 6 in (15 cm) long, set canes or a support ring, because the flowers are large enough to bend and snap their own shoots and you cannot fit supports around brittle, budded growth later.
This is the frost window. Swelling buds are killed by nights below about 28F (minus 2C) even though the plant itself is thoroughly hardy. Drape row cover over the shrub in the evening when frost is forecast and take it off in the morning. Never use plastic, which condenses and rots the buds.
Then the flowers open, and they last a week at most, less in hot bright weather. Deadhead each bloom as it goes over, cutting just below the flower head to the first good leaf, and pick the fallen petals out of the foliage and off the ground. That single habit prevents most of the botrytis you would otherwise deal with.
| Season | Jobs | What to watch for |
|---|---|---|
| Late winter | Count flower buds, remove dead wood, thin for airflow, rake and re mulch | Suckers below the graft union, dieback further than the tips |
| Early spring | Feed as buds swell, set supports at 6 in (15 cm) of growth | Frost forecasts once buds show color; slugs on soft shoots |
| Flowering | Deadhead as blooms fade, collect fallen petals | Shoots wilting with a brown base, buds rotting closed |
| Just after flowering | Second light feed within two weeks | This is when next spring's buds are set |
| Summer | Deep water only in drought, keep leaves on the plant | Drought stress now means fewer flowers next spring |
| Midsummer | Stop all feeding | Late feeding gives soft wood that frost damages |
| Autumn | Let leaves fall, rake the ground bare, top up mulch, plant new stock | Debris at the base is next year's botrytis |
| Winter | Nothing | Do not cut the stems down under any circumstances |
Summer: the quiet season that decides next spring
Within about eight weeks of the last flower fading, the plant sets the buds that will open next spring. Everything you do in that window shows up nine months later, and nothing you do next spring can make up for neglecting it. Give a second light feed within a fortnight of the final flower, then keep the plant from going into real drought stress for the rest of the summer.
Water deeply and rarely rather than often and lightly: 3 to 4 gal (12 to 15 liters) poured slowly at the base, twice a month in a genuinely dry spell, is enough for an established plant. Newly planted ones need water every week or ten days through their first two summers. Always water at the base, in the morning, never over the leaves.
Leave the foliage completely alone. It is feeding the buds, and it is also the best looking thing about the plant for the other eleven months of the year. Stop feeding by midsummer so the new wood ripens and hardens before cold weather, and do not dig or fork around the roots at any point.
- Mark the date the last flower fades Write it down. It opens the eight week window in which next spring's flower buds are formed, and it is the trigger for the second feed and for keeping the plant watered.
- Feed once, lightly, then stop A balanced or slightly potassium rich granular feed over the root area within two weeks of flowering ending. No further feeding after midsummer.
- Water deeply in drought only Two thorough soakings a month beat daily sprinkling. Check by pushing a finger through the mulch; if the soil is damp at 3 in (8 cm) down, leave it.
- Inspect for scale and botrytis monthly Look at the old bark for brown limpet like bumps and at the shoot bases for browning. Both are much cheaper to deal with early.
- Let the leaves finish their season Do not strip or tidy the foliage for appearance. Every leaf removed before autumn is energy taken out of next spring's flowers.
Autumn and winter: clear up, plant, and leave it standing
Let the leaves color and fall naturally, then rake the ground under the plant completely clean and take the debris off site. Fallen leaves and old petals held around the base are the overwintering site for botrytis, and this clean up does more for the plant's health than anything else in the calendar. Top up the mulch afterwards, keeping it clear of the bark.
Autumn is the season for planting new stock and for the rare job of resetting a plant whose graft union was buried too shallow. The soil is still warm, the plant is going dormant, and roots move before the top does. Bury the union 4 to 6 in (10 to 15 cm) deep, water in, and mark the position with a stake so the bare stems are not damaged over winter.
Through winter, do nothing. The bare woody stems are alive and carrying every flower bud for the coming spring. No cutting, no shortening, no tidying. In a very cold or exposed garden, a windbreak on the prevailing side and a mulch over the root area is the whole of the winter protection a hardy tree peony needs; the plant survives hard frost easily and it is only the swelling buds, later, that are vulnerable.
The four records that carry the year over
Keep the late winter flower bud count, with the year beside it. Three years of counts show instantly whether the plant is building, holding or declining, and only a declining trend needs action. It also distinguishes buds that formed and were then frosted from buds that never formed at all, which are entirely different problems.
Keep the date the buds first showed color and the lowest overnight temperature in the following week. Over a few years this tells you whether frost protection is a routine annual job in your garden or an occasional one, and it explains a poor spring without you having to guess.
Keep the date the last flower faded and the date of the second feed, since those two together decide next spring's bud count. And keep a note of the plant's position, the depth you buried the graft union at, and when the herbaceous suckers stopped appearing. That last note is the moment a grafted tree peony becomes a plant on its own roots, and from then on it is a much tougher and longer lived shrub than it was the year before.