How and when to fertilize peonies – for more beautiful blooms

Q: I recently bought a new peony for my backyard. This is in addition to a couple of peonies I already have. The problem is neither of my existing peonies have had as many flowers as I hoped they would, and I don't want to make the same mistake with my new plant. I'm not sure whether it's necessary to fertilize them to help them produce more blooms. If I do need to fertilize them, when is the best time and how should I do it?

A: Peonies are beautiful plants that are popular for their huge, showy blooms in early summer. They are relatively easy to look after, too, as long as you don’t attempt to move them. Once established they resent being disturbed and will repay you by not blooming for a couple of years. Keep on top of their other main requirements too. They like moist but well-draining soil, so remember to keep them watered during any hot weather spells.

They also love being pampered, so if your existing plants are proving to be a little sulky on the flowering front you may need to fertilize them, along with your latest peony addition, which will benefit too. So it's a good idea to find out how and when to fertilize peonies to get the best out of your plants.

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How to fertilize peonies

Give peonies rich, fertile soil, and they will thrive and reward you with plenty of flowers. To promote growth, apply a general-purpose fertilizer each year in spring. Then mulch with a layer of garden compost or well-rotted manure in fall to enrich the soil they're planted in.

'Fertilize peonies with a high potassium fertilizer to suit strong flower development such as a 5-10-5 ratio,' says Ben Hilton, founder of The Gardening Fix. 'Or you can apply a balanced 10-10-10 fertilizer. This ensures that your plants get the correct levels of nitrogen, phosphorus, and potassium. Nitrogen promotes foliage growth while phosphorus and potassium encourage healthy, vibrant flower production.' This  Expert Gardener all-purpose fertilizer from Amazon would be suitable as it has a 10-10-10 ratio – this refers to the plant fertilizer numbers usually listed on the label. 

It's also important to apply a slow-release fertilizer that will continue to provide nutrients and feed the plant over time, according to Ben. This can be achieved by using a granular top dressing, as opposed to a liquid feed. If you're using a natural bone meal fertilizer or chicken manure, you can apply it throughout the growing season without risk of over-fertilizing your peony plants.

Ben Hilton

Ben is founder and editor-in-chief of Theyardandgarden.com and Thegardeningfix.com, which provide valuable insights, tips, and advice on everything from plant care and growing to landscape design.

When to fertilize peonies

Peonies should be fed twice a year. First, when you see new shoots emerge in the spring but before the flower buds start to show, then again in fall to build strong roots on your plant ahead of winter. 

'It's best to fertilize peonies in the early spring, just before the buds start to swell,' says Lindsey Hyland of Urban Organic Yield. 'In the fall, you can apply a top dressing of compost or aged manure but avoid high-nitrogen fertilizers so your plant doesn't put out too much vegetative growth and neglects to flower.'

First water the soil around the plant thoroughly. After you have applied the fertilizer, being careful to avoid touching your peony's stems or leaves, water the area again to help the nutrients sink into the soil. 

Follow a spring and fall fertilizing routine for the first few years after planting a peony. Then you can ease off as peonies should only need fertilizing every three years or so, and if they're really thriving you can stop completely.

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Anne Swithinbank

Anne Swithinbank is one of the world's most established gardening experts and horticulturalists. Anne contributes regularly to Homes & Gardens and our sister title, Amateur Gardening.

Fertilizing peonies is generally a good thing but be sure to follow the label closely and avoid overdoing it. And remember that feeding is just one element of looking after these gorgeous flowering plants – you also need to know when to cut back peonies, deadhead them and keep on top of their watering needs if you're going to grow healthy and happy plants.