How to grow rare woodland peonies from seed

Why woodland peonies are worth the wait

Woodland peonies are among the most quietly spectacular plants a British garden can hold. Species such as Paeonia mlokosewitschii, with its soft sulphur-yellow bowls, Paeonia mascula in deep rose-pink, and the elegant white-flowered Paeonia emodi are rarely seen outside specialist collections. They are also expensive to buy and almost never offered as seed by the mainstream trade. Growing them from seed is slow, occasionally infuriating, and completely addictive. It also happens to be one of the most useful things a gardener can do for plants whose wild populations are under pressure.

The good news is that the technique is straightforward. The bad news is that you cannot hurry it.

Understanding double dormancy

Most peony seed does not simply germinate when it gets wet and warm. It has what growers call double dormancy, and understanding it explains almost everything about the process.

• The radicle — the first root — emerges first, usually in autumn or early winter, when temperatures are cool but not frozen.
• A small tuber forms underground and sits dormant through the following summer.
• The shoot then needs a second period of cold before it will push up a leaf, typically the following spring.

In other words, a seed sown this October may show its first leaf in spring of the year after next. Some species and some individual seeds take a third winter. That is normal, not failure. The commonest mistake gardeners make is tipping out a pot in frustration just before the shoot finally arrives.

Sourcing and handling fresh seed

Freshness matters enormously. Peony seed that has been dried and stored will germinate erratically, if at all, so always ask whether seed is from the current season.

• Collect seed when the follicles split in late summer or early autumn. The seed is often bright red, blue-black or scarlet when fresh.
• Sow within days of collecting if you can. If seed arrives by post, soak it in lukewarm water for 24 hours before sowing.
• Never let seed dry out on a windowsill. If you must store it briefly, keep it in a sealed bag with a little damp vermiculite in the fridge.
• Choose species suited to your conditions. Paeonia cambessedesii and Paeonia clusii appreciate sharper drainage, whilst Paeonia wittmanniana and Paeonia emodi relish deep leaf litter and dappled shade.

For conservation-minded growers, buy seed from cultivated stock or specialist seed exchanges rather than collecting from wild plants. Some species are legally protected, and wild populations rarely need extra pressure.

Sowing: compost, depth and containers

Peonies build a substantial root before they ever show a leaf, so give them depth. A standard seed tray is useless here.

• Use deep pots or rose pots, at least 15cm deep, filled with a free-draining mix: roughly two parts peat-free multipurpose compost, one part leafmould, and one part horticultural grit.
• Sow 1–2cm deep and cover with a layer of grit. This deters mice, which will otherwise clear a whole pot in a night, and keeps the compost surface from drying out.
• Water thoroughly, then stand the pots outdoors in a cold frame or a sheltered corner. A plunge bed of damp sand helps keep moisture even.
• Cover with fine mesh or a sheet of glass propped for airflow if rodents and squirrels are a problem.

Label everything, including the date. Two years is a long time to remember what went where.

What happens in each season

Autumn and early winter provide the mild chill the radicle needs. By midwinter you may notice a small white root when you water, or you may notice nothing at all — the root can be several centimetres down.

Through the first summer, keep pots moist but never sodden. Waterlogging rots the young tubers faster than drought. A little shade from fierce midday sun is welcome, as the roots are still shallow.

The second winter delivers the cold that triggers shoot growth. From March onwards, watch for a single reddish shoot, often looking more like a tiny claw than a leaf. Some pots will stay stubbornly empty; leave them another full year before giving up.

Growing on and planting out

Seedlings are small and slow, and they resent disturbance. Leave them in their pots until the foliage has died back naturally in autumn, then pot them on individually into deep pots using the same gritty, leafmould-rich mix.

• Grow on for two or three years before planting out. Flowering may take four to seven years from sowing, occasionally longer.
• Plant out in autumn, in dappled shade or morning sun, with the tuber set at its previous depth.
• Improve the planting hole generously with leafmould and a handful of grit if your soil is heavy clay.
• Mulch annually with leafmould, and protect young growth from slugs and snails, which find peony shoots irresistible.

Woodland peonies dislike being moved, so choose the spot carefully and then leave them alone. Give them that, and a plant you raised from a single seed will quietly outlive most of the garden around it — and carry a little of its wild heritage forward with it.