A field guide to peony forms

When people start choosing peonies, the conversation almost always turns on color first: coral, blush, deep crimson, soft cream. But form matters as much, and arguably more. The form of a peony decides how it reads from across the garden, how it holds up in rain, how long it lasts in a vase, and whether it can stand on its own stem or needs quiet support.

Singles are the simplest form. A ring of five to fifteen petals surrounds a bright center of yellow stamens. Singles open quickly, hold up beautifully in wind and rain, and feel surprisingly modern in a mixed border. They are loved by bees and have the longest vase life of any peony form, because there's so little tissue to support.

Semi-doubles add petals, typically several rows, while leaving the stamens visible at the center. They have a relaxed, airy quality that splits the difference between a single and a full double. Sturdy stems, fast opening, and a generous look without the weight of a fully packed bloom. We love semis and full doubles for their layers and ruffles.

Japanese form peonies are graceful and distinctive, and surprisingly under-planted. From the side they look like singles, but the center stamens have transformed into narrow, ruffled petal-like structures called staminodes, often in a contrasting color.

Bomb form is the one that stops people in the garden. A flat outer ring of guard petals supports a tall, rounded center that mounds up like a pom-pom. Bombs are showy, fragrant, and have real weight to them. Most need support after a heavy rain, but the trade-off is a true showstopper in the garden.

Full doubles are the classic, heirloom peony: densely packed with petals from edge to center, no stamens visible, often heavily fragrant. They are slower to open, heaviest in the rain, and the form most people picture when they think 'peony.' Plant them where you can stake them quietly and where you'll walk past them often, because they reward close attention.

There's no best form. A garden with one of each carries a longer season. Singles and semi-doubles open earliest, bombs and doubles a week or two later, and together they give you a wider range of cut flowers for the house. We tend to plant a mix and let the year decide which one is the favorite.