landscape seasonal image
     

 

Nothing says Spring, like Peonies

Nothing says Spring, like Peonies
Oh how we love the big, bold blooms of Peonies.  An all around terrific perennial shrub, peonies are incredibly drought-tolerant, deer resistant and prefer our Midwestern soil which is alkaline to neutral.  And they only get better with age.  My neighbor has peonies that have been growing for decades in full sun which they prefer.  They are just spectacular and give me an incredible ‘borrowed’ view each year.

Peonies periodically need extra care when it comes to supporting their heavy blooms as just one drenching rain can send them to the ground.  Their stems are sometimes too weak to support their big flower weight but it’s easy to protect them by using a grow-through grid system or by staking them with twine well before they bloom.  Choose a single flower variety versus the more nostalgic doubles and you won’t have to worry about bloom weight at all.

Peonies are relatively disease resistant except when we have an excessively wet spring such as we experienced in 2011.  Last year we saw a fair amount of Botrytis blight, a fungus that attacks stems, buds and leaves.  Botrytis thrives when weather is cloudy and rainy, and when soil stays wet for long periods of time.  Sanitation is key, which means you’ll want to remove infected buds, leaves and stems, and any spent flower blooms.

We expect most peonies to recover, but given the mild winter we have had, which promotes the overwintering of disease and fungus, some may succumb to the stress.  Cleaning your garden well and keeping the base of your peonies clear of debris will go a long way towards reducing the occurrence of Botrytis.  But don’t let the possibility of Botrytis deter you.  Peonies are excellent plants and they deserve a place in your garden.

Types of Peonies
Herbaceous peonies (shrub peonies) are the traditional peony plant that most people think of.  Herbaceous peonies die back to the ground every winter, come in a wide range of colors and often bloom earlier than other types.  Herbaceous peonies have longer stems, which make them a better cut flower option than other varieties.  Some cultivars produce lateral side buds which provide more than one flower per stem.

Tree Peonies are shrubs that lose their leaves in the fall but whose woody stems remain throughout the winter.  Tree peonies are not as cold hardy as herbaceous.  Tree peonies grow more slowly than other types, but their blooms are larger than herbaceous peonies.  Tree peonies are often sold by color instead of varietal name.

Intersectional (or Itoh) peonies are a cross between the herbaceous peony and the tree peony.  These peonies have the lovely leaf form of tree peonies but die to the ground in the winter.  Intersectional peonies have a nice rounded form, but are generally shorter than most shrub peonies.  Many hybrids produce one bloom for each stem, ideal for cut flowers.  Since they are a relatively new introduction and are in short supply, they tend to command a higher price.

Types of Blooms
Peonies are classified according to flower form.  All peonies have five or more large outer petals called guard petals and a center of stamens or modified stamens. 

Single

  • composed of a five or more broad petals
  • petals surround a center of pollen-bearing stamens and seed-bearing carpels

Japanese

  • long, thin central petals
  •  similar to anemones but have stamens that do not produce pollen in their center
  •  filaments of these stamens are broad and the anthers are very large

Anemone

  •  broad central petals
  •  resemble Japanese but have no anthers

Semi-double

  • have pollen-bearing stamens surrounded by a few layers of petals
  • guard petals may be clearly differentiated

Bomb-type

  • smaller petals that form a mound or ‘bomb’ in the center of the larger outer petals

Full double

  • no stamens but contain all large petals
  • central petals are as wide as the outer ones

Care Instructions
Peonies are hardy plants and require very little maintenance.  But there are a few things to do to keep them blooming at their peak from season to season.

Fertilize only in the spring, with an organic fertilizer when the stems are 3” high.  Ensure that the fertilizer does not touch the crowns of the plant directly, as it can damage the flower’s development.  Apply fertilizer at least 6 inches from the crown and mix thoroughly into the surrounding soil.  Cover the soil with organic mulch to protect the soil’s additives, retain moisture when the summer heat comes, and reduce weed growth.

Promote larger flowers or more abundant, yet smaller blooms with proper pruning of the flower stems.  Some varieties develop small lateral buds near the base of the terminal bud.  If you want larger flowers, remove any side buds so that the plant’s energy is concentrated on the terminal bud at the end of the stem.  (Side buds can be removed once they are pea sized and by pulling downward or sideways.)   If you choose to leave the side buds this will prolong the plant’s blooming period since the side buds bloom later than the terminal bud.  When the flowers finish blooming, cut the stem of each spent flower close to the base of the first healthy leaf or the next set of lateral buds.  Be sure to cut low enough on the stem so that you cannot see the cut.  Pruning will promote larger, healthier flowers for those buds still on the plant and allow the peony to store energy for next year’s blooms. 

In the fall, after the first few hard frosts or when the foliage is brown cut the stems off 1-2” above the ground.  To reduce the chance of spreading Botrytis, dispose of all the foliage in the garbage.  Do not compost.

Water regularly at least every two weeks during the dry, hot summer months to ensure good flowering the following year.  Always water at the roots and in the morning if possible so if the leaves get wet, they have a chance to dry off before nightfall.  This prevents the onset of diseases.  Do not water past September in order to encourage dormancy in the roots.

Reprinted from MODE Landscape Design Vol 7: Nothing Says Spring, like Peonies, March 2012

Download and Print this article here.