ing in herbaceous peonies (and this is true for Blooming in herbaceous peonies (and this is true for most plants) is controlled by factors like light, nutrients, the premature removal of foliage, recent transplanting, and also various plant diseases (often triggered by weather conditions). Planting depth can also affect peonies adversely. The details:

light

Are your peonies getting enough sun, or has a nearby tree or shrub grown and reduced the amount over the years (hence a recent decline in bloom, perhaps)? Nearby trees can pose another challenge: When peonies try to compete with extensive root systems of large woody plants, they can lose…meaning reduced bloom. Peonies ideally want a minimum of six hours of full sun a day (you may be able to skimp a little in the more southern part of their hardiness range, Zone 8).

nutrients

Overfeeding peonies, which can even happen inadvertently if they are planted beside a lawn that’s being fertilized heavily, can result in bountiful foliage and no blooms. Best to feed them compost or a balanced, all-natural organic fertilizer (never one high in Nitrogen), or some experts like bone meal. If your soil is good, just a sidedressing each year with compost will do nicely.

foliage

The untimely removal of foliage (too soon, before it can nourish the roots below by “ripening” intact on the plant) will reduce or eliminate peony blooms. Cultivate healthy foliage all season long; cut back to near the ground only after frost.

planting depth

With peonies there is also the “too deep” thing–they really do know if the growing points, or eyes, are buried more than about 2 inches beneath the soil surface. Though the roots will work to right themselves gradually (true!), too-deep planting can delay bloom until the plant makes its way into a better position (unless you bury it so deep it never can adjust).

excess soil moisture

Damp, poorly drained spots will be havoc for peonies. Why waste such a wonderful plant that promises many years of reward by sentencing it to this?

recent upheaval

Was your plant recently acquired, or recently transplanted? Peonies can sulk for a year or more after planting, especially when moved in fall, which is when they make their flower buds. Though that’s an ideal time to move them for many reasons, it can also be a bit of a distraction from their otherwise primary task of bud-production.

diseases and weather