How and When to Fertilize Peonies for Their Best Blooms Yet, Say Garden Experts

Peonies are among the most beautiful flowers in your garden, providing a splash of vibrant color with their delicate blooms. These charming perennials will return year after year, rewarding you with a show-stopping display every spring.

However, you may be wondering if it's possible for your peonies to produce even more blooms. The key? Proper fertilizing. If you're itching to see even more blooms in your garden, don't skip this important step. While fertilizer is not the default fix for poor blooms—peonies may not need feeding if they get full sun and proper watering—a low-nitrogen, bulb-type fertilizer can really give them a boost. Here, we asked experts how and when to fertilize for even fuller flowers.

When to Fertilize

Timing is key when it comes to proper fertilization. It's best to fertilize your peonies twice a year: in early spring and again after the plant is done blooming. Doing so will reward you with "armfuls of luscious blooms," says gardening author Kathy Jentz.

Fertilizing in early spring will give your peonies a jumpstart as they emerge from dormancy. The exact timing of the second fertilizing will depend on your zone and when your peonies are done blooming. This is the most critical time to fertilize, as it's when your plants are storing energy to produce blooms next year.

How to Fertilize

It's always best to check your soil before fertilizing. "I strongly recommend soil testing to determine which nutrients the soil is missing," says Lorraine Ballato, gardening expert and author of Success With Hydrangeas. "No plant uses nutrients in the same amount, and balanced fertilizers can contribute to runoff and local pollution." She recommends keeping soil composition and moisture retention top of mind when selecting a fertilizer.

Jentz recommends a slow-release fertilizer in the spring, when peonies are emerging from dormancy, and a liquid fertilizer in mid-summer or early fall when these plants are finished blooming. "Fertilizer shouldn't be applied directly around the stems of the peony," she adds. "It should be applied in the dripline region."

In particular, she says that using a fertilizer formulated for bulbs, such as Epsoma Bulb-tone, is a good idea. These fertilizers often encourage peonies to produce fuller blooms. Bone meal is another great option that helps with root growth.

However, always make sure the fertilizer you use is low in nitrogen. High nitrogen fertilizers can put peonies at risk for disease.

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How to Keep Blooms Full

Fertilizing is one element of producing full, beautiful peonies—but it's not the only one. Here are a few tips and tricks from Jentz:

• When planting, amend the planting hole with peat and mulch over very lightly with leaf compost. Don't fertilize at the time of planting.
• Peonies are shallow-rooted, so don't dig around their crown area too much.
• Heavy blooms may need staking or support.
• If a storm is on its way and your peonies are in full bloom, then cut your blossoms. A hard rain will pummel and destroy them.