Planting a Peony
You've bought a peony root, now what?
In your hand is a gnarly, ugly wad of roots, but in your mind are the gorgeous scented ruffles of your peony's future blooms. What have you done? Never fear! Ugly babies, as they say, often grow up to be quite handsome adults, and these are going to be some of the handsomest. We're going to get from here to there, together.
When should you plant your root?
Peony roots are generally planted in the fall, and potted plants can be planted in the spring. They're easier to transport in their bare root form. Once they're growing in a pot, they're too cumbersome to ship, so potted plants are more likely to be available only locally. The instructions for planting an actively growing, potted peony plant are the same as for a root, except you're likely to be planting in the spring. Be careful not to damage the top growth.
The window of when to plant peony roots is pretty wide in my area. From about the time it gets cool enough to be pleasant in the garden again until about early January, you can plant peonies. As soon as you plant and water your root, it begins to grow feeder roots that will sustain it through its critical first year, so earlier in the fall is better.
If you have to keep your root for a few days before planting it, put it in a plastic bag only loosely closed. You don't want your root to dry out, which will happen if you leave it lying out somewhere, but you don't want it to begin to mold like it will if you wrap it too air-tightly. If you have room for it in the refrigerator, all the better, but don't forget it in there!
Where will you plant your root?
The planting location for your peony plant is worth taking some time over. Peonies will live for decades if they're happy, and their root mass can grow up to 3' across. You may have to dig your plant up many years from now to divide it if the bloom begins to decline, but it would be better not to have to until then. Your shoulders will thank you for picking a good spot and not making them shovel your peony back out of there.
Of course, the roots of a happy peony plant will increase in mass and those of a miserable one will dwindle, but dwindling in misery isn't what you want either. So what makes a happy peony you can leave in place for your children to divide?
Sunshine: 6+ hours a day are optimal for the plant growth required for big beautiful blooms. Too little sun and your plant may refuse to bloom. In hot-summer areas, like mine, your peony will appreciate a little afternoon shade. Peony petals naturally fade from stronger colors to softer ones over the bloom time, but in full, all-day sun they will fade much more quickly.
Drainage: Root rot, caused by constantly wet soil, can damage or kill your peony plant. Soils high in clay, like mine, resist draining. Your plant won't thrive in a low spot where water stands after a rain, but will be happier if it's in a relatively high spot with good drainage. Improve the drainage of the soil in your selected planting location by incorporating some fine-shred bark mulch or compost with the soil.
Space: Your peony plant is ultimately going to grow between 2 and 3 feet tall and wide, depending on the variety. It will take it a few years to get to that size. You can plant annuals near your peony for the first couple of years, but not other perennials.
Will your new peony like your soil?
Peonies don't need especially rich soil, as long as the drainage is good. If you've been improving the soil in your flowerbed for some time, your soil may be just perfect for your peony plant. Peonies appreciate a pH of 6.5-7, or around neutral. Soil in my area tends acidic, so I get a soil test and add pelletized lime at the rate recommended.
How should you plant your peony root?
Now you're ready to plant. Dig a hole around 12-18" deep and the same width. Mix in your compost or fine-shred mulch now if you need it to improve drainage. Replace some of the soil in the hole and spread the roots out over it if you can. Not all peony roots are the right shape for this. The important thing is to get the crown of the plant 1" below the soil surface, with most of the roots pointed downward in the hole. The crown is where the roots come together, where the majority of the pink eyes will be.
Herbaceous peonies will be completely covered with soil when they're planted. Itoh peonies may not be. They retain some woody aboveground growth from year to year. Sometimes there are above-ground eyes. For both types of peonies, the crown should be 1" below the surface of the soil.
If you're planting peonies in places farther north than I am, you'll need to plant your roots deeper. Check with your local extension service for exact depths.
How often should you water your peony plant?
When your root is tucked into the soil, water gently but thoroughly. The soil may shift or settle after this initial watering. Adjust the root depth if needed.
The first fall, water your peony every two weeks only if there isn't any rain and the soil is dry. In the winter, my soil generally stays moist and that is adequate to establish feeder roots. If your soil is very dry during the winter, you can water every couple of weeks.
And you've done it! There are other care tips that I'll share as we go along, but you've done the most important part and gotten started. It may take a while, but those ruffly blooms are on their way. I can almost smell them.