The first summer I lived in Alaska, my neighbor brought over a bouquet of large, lush pink flowers that I had never seen before. Set in vases against the green walls in my house, I could stare at them for hours.
I soon learned that peonies (Paeonia spp.) are a big deal in Alaska.
Lots of Alaskan gardeners grow these cold-hardy blooms, which thrive in USDA hardiness zones 3-8.
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There are three different types of peonies, all of which are long-lived perennials:
Herbaceous varieties, which are perennial shrubs that die back at the end of the growing season and require a period of dormancy and cold before blooming again the following spring. The tree varieties, which can grow up to six feet tall, are deciduous shrubs and lose all their leaves in the fall, remaining bare-branched throughout the winter. Intersectional varieties, also known as Itoh peonies, are a hybrid cross of herb and tree types and boast larger flowers that typically bloom for three weeks—longer than either herb or tree types. .
Depending on the cultivar, the petals may be single, double, or semi-double. You can find out more about how to grow these lovely flowers and the different varieties in our growing guide.
After reading the above descriptions, you probably have an idea of what peony plant does in winter time.
This is correct. It sleeps.
But how much idling does it need? How many hours of cold temperature? And is there anything you can do to keep your peonies warm during the winter?
In this guide, you’ll learn everything you need to know about how to care for your peonies over winter.
Here’s what we’ll cover:
Peonies need cold exposure
Here’s the funny thing about beautiful paeonia: If you live in zone 7 or 8 you’ll actually need to pay more attention to winter care than if you’re in zone 3 or 4.
Most varieties require between 500 and 1,000 chilling hours, approximately 20 to 42 days at temperatures between 32 and 40 °F.
Since bud development is stimulated by cold hours, your plants need about a month of cool winter weather to bloom in spring.
If you live in Zones 3-5, you’re guaranteed at least a month, if not six, of below-freezing temperatures.
I’m looking at you, Alaska.
Peonies don’t mind the extra chill time that comes with long, cold winters, but if you live in Zones 6-8, you may have to contend with near-freezing temperatures throughout the month.
But since peonies don’t grow from bulbs, it’s not a good idea to try to pull them up and keep them indoors, as you might with spring-flowering bulbs.
So how can you keep your peonies cool enough through zone 6, 7, or 8 winters?
Fear not, because I have some tips.
View Your Planting Depth
Peonies grow from tuberous roots with “eyes” that grow new shoots.
For Paeonia to thrive, it needs to be planted at the right depth. For those of you who live in zones 3-5, it is best to plant the tubers so that the little pink eyes from which the leaf stalks grow are two inches below the soil surface.
Can you see the little pink bud in the picture below? It is the “eye” of the plant.
Photo by Laura Melchor.
It is recommended to apply it exactly two inches deep. So get out your ruler to make sure the eyelet has the depth of planting it needs.
For those of you in Zones 6 and 7, the seedlings should be planted just an inch below the soil surface. and in Zone 8, just a half inch below.
This perfect planting depth gives it the best opportunity to thrive and produce lots of gorgeous, heavy blooms.
The reason for the different planting depths is that peonies in warmer regions will be exposed to colder air temperatures, while in cooler regions they will stick down just a couple of inches for little protection during winters that can be as cold as -40°. F.
when and how to cut them back
Whether or not you should cut your plants back to the ground depends on the type of peonies you’re working with.
But regardless of type, you need to let all the leaves die back naturally at the end of the growing season.
Once they’re nice and yellow or brown — this will usually happen after the first frost in your area — it’s time to cut the stems of cultivated weeds to about an inch above soil level.
Photo by Laura Melchor.
Throw trimmed vegetation in the trash instead of the compost pile. This helps eliminate any disease that may be living on the leaves from re-infesting your plants the following spring.
You don’t need to do anything special for the type of trees you want to cover in fall. If you like, you may want to prune them lightly in the spring to maintain their shape, but it’s nothing to worry about just yet.
Learn more about how to prune peonies in our guide. (coming soon!)
And for crossbreed cultivation, you’ll want to prune them back to about four to six inches in height, leaving at least one or two growth nodes on each branch.
However, in colder regions, you may want to cut the crosses back to about an inch above the ground, as you would for herbaceous varieties, since the buds may not survive above ground for the winter. New stalks will grow in the spring, regardless.
To make sure you don’t accidentally trample your precious peony come wintertime, use a plant marker to indicate where it is located.
Should You Mulch?
The next step in keeping your peonies happy through the winter?
Smart mulching habits, which sometimes means no mulching at all.
Since planting depth is critical to a peony’s health, it makes sense that adding an inch of mulch on top of the soil could affect the plant’s ability to thrive and flower.
I once made the mistake of spreading mulch around the crown, and didn’t care for that treatment. So then I moved it to my flower bed and left it undisturbed, where it was very happy!
until my dog dug it up. I think he thought it was a stick I had planted just for him.
Newly planted peonies in zones 3-5 can benefit from an extra thin layer of breathable mulch—straw, for example—to help them stay comfortable throughout the winter, and provide a little extra protection. .
But even if you do use straw, you don’t want to put it too close to the trunk of a tree type. Placing mulch right above the stem can trap unwanted moisture in the soil around the root of the tuber, causing plant rot or diseases that otherwise would not have killed it.
Avoid mulching altogether in Zones 6-8. You’re already planting the eyes just an inch or a half below the soil surface to expose them to as much cool air as possible.
Mulch will provide them with the heat they don’t want.
Choosing the Right Cultivator
While these beautiful perennials do best in cool climates, those of you in zones 7 and 8 and even parts of zone 9 can help ensure success when you choose cultivars that are better suited to your warmer climates. Be friendly with
Look for varieties that are described as early bloomers and single or semi-double flowers.
These types do better in warmer climates. ‘Green Lotus’ is an attractive, early blooming, single-flowered cultivar to grow.
Pink in color with pale green petals, it’s sure to grab the attention of your neighbors and mesmerize you every time you see it.
You can find tubers for fall-planting online at Eden Brothers.
One of my favorite early bloomers is the lovely Itoh hybrid, ‘Julia Rose.’
With semi-double, fragrant petals in varying degrees of pink, the plant can produce up to 50 blooms in a single season.
Search ‘Julia Rose’ for fall plantings, also available from Eden Brothers.
Winter Care Means Forever Blooming
OK, maybe not forever. But if you take good care of your peony plants, they will gift you a long life. It is well documented that these plants can live up to a hundred years.
So they’ll probably outbid you. What a gift to the next generation!
Are you growing peonies? Do you have any winter care tips to share? I would love to hear from you in the comments section below.
And for more information on growing peony flowers in your garden, check out these guides ahead:
Photos by Laura Melkor © Ask the Experts, LLC. All rights reserved. See our TOS for more details. Product photos via Eden Brothers. Uncredited photos: Shutterstock.