Peony Care Q&A: How to Fertilize for Stunning Blooms Every Season
Q: When’s the best time to fertilize my herbaceous peonies, and how can I encourage healthier, more beautiful blooms in my Zone 6 garden? I’ve been struggling to get my peonies to reach their full potential—they either have fewer flowers than I hoped for or seem a bit lackluster throughout the season this year. I’d love some expert advice on the proper fertilizing routine, including soil preparation, nutrient timing, and any common mistakes to avoid. Are there specific products or techniques that really help peonies thrive in this zone? I’m eager to make sure they get exactly what they need to flourish next year! – from Jill
A: When it comes to fertilizing herbaceous peonies, timing is everything. For new plants, I like to start in spring as soon as those little red shoots peek through the soil, signaling they’re ready for a boost. For mature peonies, I wait until the buds are setting up shop—usually later in spring.
In my garden, I’ve had the best luck with a mix of finished compost and either bulb fertilizer or a 10-20-20 granular formula. A word of caution: keep the fertilizer well clear of the crown! Getting too close can harm the plant, sometimes beyond repair.
And if you’re tempted to add a little extra? Resist! Overdoing it, especially with nitrogen, will slow down flower production—which is exactly what we don’t want.
Start With Compost
Compost provides all sorts of helpful slow-release nutrients for herbaceous peonies, and it plays a few critical roles in keeping them healthy and happy.
For starters, compost enriches the soil with organic matter, which helps improve its structure, drainage, and overall health—all things peonies love.
It’s especially handy if your soil tends to be heavy clay or too sandy, as compost can loosen up clay while adding a bit of body to sandy soils, helping peonies anchor their roots and get a steady flow of water and nutrients.
I always apply a top dressing of compost around my peonies in early spring, just as new shoots are emerging. This gives them a gentle boost for the growing season without overwhelming their root systems.
By adding compost regularly, you’re essentially giving your peonies a long-term investment in soil health, which is the foundation for better blooms and a stronger, more resilient plant overall.
When and How Often Should You Fertilize
For herbaceous peonies, timing and moderation are key when it comes to fertilizing. I usually fertilize twice a year, which keeps my plants healthy and blooming beautifully without overdoing it.
Early Spring: The first application goes on in early spring, just as those little red shoots start poking through the soil. This is the plant’s cue that it’s waking up and ready for some nutrients to fuel its growth. A balanced fertilizer, like a 10-20-20 mix, provides the nutrients needed to support both root development and upcoming flower production.
Late Spring/Early Summer: The second feeding happens after the plants have bloomed. This timing is key because peonies expend a lot of energy in flowering. Giving them a post-bloom boost—usually with a lower nitrogen fertilizer—helps restore what they used up and prepares them for next season’s growth. A 5-10-10 mix works well here, or simply another top dressing of compost if you prefer a more natural approach.
One important thing I’ve learned over the years: peonies are pretty self-sufficient, so too much fertilizer, especially nitrogen, can actually reduce flowering and lead to lush foliage without the blooms. A light hand is best; twice a year is usually all they need for a productive, healthy season.
My Favorite Fertilizers for Peony Plants
When fertilizing, use a general bulb fertilizer or NPK 10-20-20 fertilizer. An NPK 5-10-10 (lower concentration fertilizer) is great for top-ups when your plants are already performing well.
There are a few commercial products (via Amazon) available close to these ratios that are also great for use on other plants:
Keep weeds to a minimum to avoid competition around the roots and maintain the right nutrient levels.
How to Apply Fertilizer
The application will depend on your chosen product. Some fertilizers are spread around the plants and gently dug into the soil, while others are diluted in water and applied to the soil with your regular watering schedule.
Remember that fertilizers come in different concentrations and need to be diluted or added following the instructions exactly. Overfertilizing will burn the roots and leaves and can stunt growth. It’s always better to apply too little than too much.
Always avoid applying the product directly to the crown when composting or fertilizing. Feed the soil around the plants instead, right where the foliage stops.
Key Considerations
Overfertilizing
As mentioned before, too much of a good thing is as much a problem as too little.
Stick to the guidelines on the packaging of the Fertilizer you have bought. Apart from these general guidelines, only apply a particular fertilizer if your plants lack a particular nutrient. This will prevent any imbalances or problems with salt build-ups in the soil.
Using the Incorrect Fertilizer
Avoid using fertilizers high in nitrogen during the peony growing season. These promote excessive soft growth that is vulnerable to disease. Too much nitrogen will also discourage flowering by directing the plant’s energy toward foliage growth.
Wrapping Up
These easy-to-grow plants can become stars in your garden with some basic care, but only if properly placed and fertilized. They are one of the most glamorous of perennial flowers, and the vast array of colors is a welcome addition to any garden. With the right approach, you could have 100-year-old peonies in your garden (if, of course, you last that long).
For more, see our complete guide on how to grow peonies in your garden.
Madison is a writer and editor with a Bachelor’s degree in History and Political Science. She writes and photographs for various online and print publications in the gardening sphere and is the author of the book The Next-Generation Gardener.