All About Herbaceous Peonies

Peony flowers come in many forms including bomb, double, single, semi-double and Japanese.  Most plants are two to four feet tall and they die back in the late fall.  They’re available in a large range of colors and can be planted to bloom in succession for a long season of showy flowers.  Some peonies also have a heavenly fragrance. 

Herbaceous peonies are a relatively easy plant to grow in zones 3-8.  With good snow cover they can be safely grown in zone 2.  They require at least 20 to 40 days of temperatures between 32°- 40°F to flower.  They’re most often purchased as bare roots but are sometimes available as potted plants.  Purchasing them from a reputable dealer will give you the best chance to get a plant that will bloom the first year.  Bare root peonies are planted in early Fall to give them time to establish roots before winter sets in.  If you purchase a potted plant it should be planted in early Spring.

Fern leaf peonies are a specific species of herbaceous peony.  The foliage is soft and needle-like, looking much like a fern.  They bloom early in the season and are usually about 16 inches tall.  They go dormant and die back much earlier than most herbaceous peonies.

It’s normal for herbaceous peonies to live 30 years and there are even records of them living up to 100 years!  Since they live for so long, pick a location where they’ll receive at least six hours of sun a day and can remain undisturbed for many years.  If you live in an area with real hot summers, they’ll benefit from a little afternoon shade.  If planted in too much shade they may not flower and are more subject to diseases.  They don’t like to sit in water so provide good drainage. 

Prepare your planting area in advance.  Dig a hole about 12-24 inches across and 18 inches deep.  Add rich compost or well rotted manure to the soil you remove from the hole.  If you have sandy or clay soil you’ll most likely need more amendments to improve it.  Replace most of the amended soil back in the hole.  Peony roots are planted so the tip of the root is downward and the eyes are up.  The eyes should be no more than 2 inches from the surface of the soil when you’re done planting.  Planting any deeper could result in flowers not developing.  If you plant too shallow the tops of the eyes could freeze and die.  Back fill the remaining soil and water in well.  In their first year they’ll benefit from regular watering but once established they’re quite drought tolerant. Try to avoid overhead watering because the flowers can get heavy from the water and bend or break.  If planting more than one peony, space three to four feet apart.

If you planted your peonies in good fertile soil they shouldn’t need any fertilizer for many years; generally they thrive on neglect.  If given too much fertilizer they’ll produce leaves instead of flowers.  The best way to keep them happy is to spread compost on your gardens or use fish emulsion to drench the roots.  If you have very porous soil the nutrients will be washed away faster and you may consider using a slow-release fertilizer.  They’re bottom feeders so you'll want to keep fertilizer away from the crowns.  Spreading it 6 to 18 inches away from the crown will cover the area where the roots grow.

When weeding your peonies remember that they have shallow roots.  If you cultivate more than 2 inches deep you could possibly injure the roots.

Since peonies are quite tall and most of them have large flowers, when they’re wet or in windy conditions they tend to flop over.  The best way to prevent this is to stake your plants.  They grow fast so you should put your supports in as soon as they come out of the ground.  There are rings or hoops made specifically for supporting peonies but sometimes these are too short.  Tomato cages work but might not be wide enough.  You can put stakes in the ground around the outside of the plants and make a grid pattern with twine for support.  There are lots of creative ways that would work so let your imagination be your guide.

And what are the ants doing, those that you always see on your peony buds?  They’re eating!   The flower buds produce a sweet nectar that ants love.  They’re not eating the plant and despite what you’ve heard, ants aren’t necessary to open the buds. 

Sometimes your peonies don’t bloom.  There’s quite a few reasons this can happen:  planted too deep, too much competition for nutrients by crowding with other plants, plants are still very small, too much shade, temperatures have been too hot, late frost damage, soil not draining well or disease. 

The best way to prevent disease is by providing good air circulation around your plants and removing plant debris. Peonies can be affected by Botrytis (young stalks wilt and die and buds turn black), bud blast (a fungal disease that turns buds black and they dry up), and powdery mildew (powdery white patches that cause leaves to turn yellow and drop, stunted growth, distorted buds and blooms, and weakness in the entire plant).  With the exception of bud blast, these can generally be treated.  There’s also a fungal infection called Cladosporium or peony measles.  Small red spots appear and turn into large dark spots.  This isn’t fatal but it’s not attractive.  Just be sure to remove debris from your garden during fall cleanup.  On a good note, deer are not attracted to peonies.

In the fall after the stems dry up or after the first freeze, herbaceous peonies should be cut back to 2 inches above the ground and the debris removed from the garden to prevent diseases.  If you cut the foliage back too soon it can eventually affect the flowering of your plant.  The first winter after you plant it’s a good idea to mulch with 3-4 inches of mulch after the ground freezes.

When planning your gardens this year, be sure to include a few of these regal plants in your design.  And if there's no room in your garden it's well worth it to dig a new garden so you can include and enjoy the beauty of these long-lived plants.

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