Peonies are one of those plants that look effortless when they're doing well. Masses of huge blousy flowers that seem to appear out of nowhere every spring. But if you've ever had a peony that produces loads of leaves and barely any flowers, or worse, flowers that flop to the ground at the first bit of rain, you'll know they can be a bit frustrating.
The good news is most peony problems come down to a few simple things. Get these right and you'll be rewarded with the kind of flowers that stop people in their tracks. Here are the 9 steps I take to make sure mine perform.
1. Check The Planting Depth
This is the most common reason peonies don't flower. The crown (where the shoots come out of the roots) needs to be no more than 3-5cm below the soil surface. Any deeper and the plant puts all its energy into leaves instead of flowers.
If yours has been in the ground for years and never flowers properly, it's worth having a gentle dig around in autumn to check. If it's too deep, lift it and replant at the right level. It's a faff but it makes all the difference.
2. Feed Them Now
Peonies are hungry plants and they need feeding early in the season. A handful of bone meal or a balanced granular fertiliser scattered around the plant in late winter or early spring gives them what they need just as the shoots start pushing through.
Don't use high-nitrogen feeds. You'll just get lots of leaves and no flowers. Look for something with a bit more potassium and phosphorus.
3. Get The Support In Early
This is the one everyone forgets. You need to get plant supports in place before the plant gets big. Once those stems are up and starting to bud, you've missed your chance.
I use metal grow-through supports that sit over the plant in early spring. The shoots grow up through the grid and by the time the flowers open, the support is completely hidden. Without support, those massive flower heads will end up face-down in the mud after one rainy day.
4. Mulch Properly
A good mulch in spring does several things. It feeds the soil, keeps moisture in, and suppresses weeds. Use well-rotted compost or manure and spread it around the plant.
But here's the important bit. Don't pile it on top of the crown. Keep it a few centimetres away from the shoots. Burying the crown with mulch has the same effect as planting too deep. No flowers.
5. Remove Weak Growth
If your peony is well established, you'll probably see loads of shoots coming up. Not all of them will produce good flowers. Remove any thin, weedy-looking shoots early in the season so the plant focuses its energy on the strong ones.
This is the same principle as pruning fruit trees. Fewer, better blooms rather than masses of mediocre ones.
6. Disbud For Bigger Flowers
Each flowering stem usually produces one large terminal bud and several smaller side buds. If you want really huge blooms, pinch out the side buds when they're still small. All the energy then goes into that main flower.
I don't always bother with this. I quite like having a longer flowering period with the side buds blooming after the main one. But if it's the show-stopper blooms you're after, disbudding is the trick.
7. Water During Bud Formation
Peonies don't need much water once they're established, but there's one crucial time when you shouldn't let them dry out. When the buds are forming and swelling. This is usually April and May.
If it's been dry, give them a good soak once a week. Aim for the soil, not the leaves, and water in the morning if you can. Dry conditions at bud formation means smaller flowers or buds that don't open properly.
8. Watch For Peony Wilt
Peony wilt (botrytis) is the main disease to look out for. You'll spot it as blackened stems that suddenly collapse, often just as the buds are forming. It's most common in wet springs and poorly ventilated spots.
If you see it, cut out affected stems immediately and bin them. Don't compost. Improve airflow around the plant by removing any surrounding plants that are crowding it. A preventative spray isn't really necessary if you keep on top of hygiene.
9. Leave Them Alone
This is the one that sounds like it shouldn't work, but it does. Peonies hate being moved. If you've got one that's established and doing well, don't mess with it. Don't divide it, don't move it, don't fuss.
Peonies can live for 50+ years in the same spot. The longer they're there, the better they tend to flower. If someone tells you to divide them every few years like other perennials, ignore them. These plants reward patience more than any other I grow.
Final Thoughts
Peonies aren't hard to grow, but they do like things done properly. Get the planting depth right, feed them, support them, and leave them alone. That's really the whole game.
The other thing I'd say is don't panic if a newly planted peony doesn't flower for a year or two. They're notoriously slow to settle in. Mine didn't do much for the first couple of seasons and now they're the best thing in the garden come June.
Worth the wait, every time.
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