Peonies – How to Plant, Grow & Care for Peony Plants
Our customers want to know all about peonies. I put together a list of frequently asked questions and comments regarding planting, growing and care of peonies. These luscious flowers are rather simple to grow and are long-lived perennial plants.
Cold Winters - Can I grow peonies in my area – we have snow on the ground for days/weeks at a time? Yes, peonies love cold winters. Peonies grow well in USDA zones 2-8. Peonies need a cool period in the winter, for dormancy, ensuring their buds will open to grow stems and flowers in the spring. Snow and frost are fine. Find your zone on the USDA hardiness zone map. If you are not in zones 2 – 8, ask local gardeners if they have had success with peonies.
We had customers from the Midwest visit and tell us they had 100 year record breaking cold temperatures in 2014 and the peonies were the flowering plants that survived and thrived. We learned that our California peony gardeners enjoyed their best peonies in 2014, because of a colder winter. Peonies love a winter cold spell.
Warmer Winters – I live in an area with warmer winters, can I grow peonies? One of our customers in USDA zone 9B reports that she lives in an area ‘where you can’t grow peonies’. She now has 25 peonies and she finds greatest success when she covers the eyes (buds) of the peony roots with just a thin sprinkling of soil. Her area does have temperatures in the 40’s many nights in the late fall and winter, which makes it possible to grow peonies. Another customer in Palm Springs, CA grows fabulous peonies. She sets ice bags along her peony beds once each week, for three weeks in February. The photos she showed us of her huge plants were spectacular. While peonies do not grow well in all warm winter climates, some ambitious gardeners give it a try and some find sweet success.
Soil Types and Amendments - Do I need to amend my soil? This may or may not be necessary. Do you need to amend your soil for other plants, or do they just grow in the dirt for you? A lot of topsoil is removed when houses are built and some areas have poor quality soils, so adding some good soil may be needed. Soil amendments can improve drainage and increase the nutrients that are available to your plants. This can be very beneficial to plant growth. Spade up some of your regular garden soil with some old compost or good potting soil and place in your planting holes. You can always try one peony in amended soil and one planted in just plain back yard dirt and observe their growth for differences.
When to Plant Peonies – When do I plant peonies? Plant bare root peonies in the fall (September through November is prime peony planting time). Peonies from containers or pots can be transplanted in the fall or spring.
Planting Site Selection – Where should I plant my peonies? Plant a peony in a sunny, well drained location. Peonies need a half day or more of sun to bloom well. They love full sun, although a bit of shade can be beneficial, adding to the vibrancy of the flowers. Space peonies about 30” to 36” apart, to allow good air circulation between plants.
Prepping the Planting Site – How big of a hole do I dig? Dig a hole about one foot deep and one foot wide. A larger hole may be dug for extra large roots. Spade the soil you removed, so it is friable (small, crumbly pieces); this will allow the roots to easily expand as they grow. Fill the hole back in with the spaded soil you just removed. Scoop out enough soil to lay the root in.
Planting Depth – How deep do I plant my peonies? This is perhaps the most important question on planting peonies. Peony plant roots are planted with the buds ‘eyes’ very close to the surface of the ground. They should have only one to two inches of soil covering the buds ‘eyes’. Sometimes when people read ‘plant a peony root 1”-2” below soil’, their interpretation is to plant a peony root ‘twelve inches’ below soil and they plant it much too deeply. That’s why we say to cover the peony buds ‘eyes’ with one inch to two inches of soil. Planting too deeply will result in slower growth or loss of the root.
Peony Root Placement - Should the peony root be placed at an angle or straight up and down? A peony root is placed with the buds ‘eyes’ at about ground level. The buds (eyes) will be pointing upward, with the thick, fleshy roots pointing downward, at any angle. Be sure the buds ‘eyes’ are on top. The roots will then grow vertically, as well as horizontally. Cover the root with soil, putting just an inch or two of soil over the top of buds ‘eyes’.
Peony Eyes – What are peony eyes? Peony eyes are buds at the top of the roots. They are often pink, white or red in color. A peony root consists of a crown, where the buds ‘eyes’ are normally found and longer, fleshy roots. Sometimes the eyes are in various places on a root. The buds or eyes will open up in the spring and grow into peony stems. Each stem will produce a flower upon plant maturity. You often get a flower or two the first year; more stems and flowers the second year and a nice, full peony plant the third year.
Planting in Well Drained Clay Soil – I have clay soil, will peonies grow in it? I mentioned in a newspaper article that peonies love clay soil. We had numerous visitors come to the farm to tell us they were pleased to hear that. Then one woman showed up and said, “I have clay soil, hard clay, well drained and peonies are what grow best in it. I saw the article and had to come get some more peony plants.” Many of us peony farmers are growing peonies in various types of unamended clay based soils – plain old dirt. Yes, it gets hard when it is dry; but, a bit of water now and then will soften it up for the roots to roam and grow. When you plant new peony starts, spade a good sized hole to loosen the soil into a crumbly texture. With a little water, your plants will be able to take off from there. To further enrich your soil or to give it a looser texture, you may add some old compost or potting soil into the planting hole.
Proper Drainage - What if I have poor drainage or am not sure? After a good rain, we see puddles of water that generally drain in a reasonable amount of time. This is okay. If you have areas that are always water logged (marshy) for days after a normal rain, those areas may be too wet for peony roots. Peony roots should not be in consistently, prolonged wet conditions. You can build raised beds or make mini hills (mounds) for your peonies to increase the drainage. To make a mini hill or mound: prepare your planting hole and fill it back in with spaded soil. Either place the root on top of the ground (ground level) or build up the soil mound to set the root a few inches (or higher) above ground level. Cover the root until the eyes have one to two inches of soil over them. Your mounds will have the root in the center. Water the root a bit and add more soil if needed to keep a nicely shaped mound.
Watering Peonies - When should I water my peonies? Water newly planted peonies promptly upon planting. Check the peony plant or root in a day or two to see if the root settled too deeply. Reposition it higher, if needed, by lifting it and placing more soil under it. Re-cover the root with soil. Baby peony plants need water to thrive – give them a drink every couple of weeks throughout their first fall and summer (unless the rain does that for you). Keep the soil slightly moist, not saturated. As peony plants mature, they can thrive on less water and are rather drought tolerant, although a good watering now and then will be beneficial.
No or Little Bloom – Why doesn’t my peony bloom? This is often related to planting too deeply or being in too much shade. Peonies love sun. As our landscape trees and shrubs grow up, they provide more shade. Years can go by and we don’t really notice that the peonies are not getting enough sun to bloom. You can relocate peony plants in the fall to ensure proper planting depth or adequate sun. Plant peonies in an area where they will receive at least a half of day of sun. Too much nitrogen (from lawn fertilizer) may also be the cause. And, of course, we need to be patient with baby peony plants – they are establishing big roots which will produce bigger plants with more flowers as they mature. While many first year peony plants produce a blossom or two, it is normal to have the first blossoms their second year.
Peony Care in the Fall – What do I do to my peonies in the fall? The leaves and stems of herbaceous (bush) peonies, including the intersectional Itoh peonies will provide nice foliage in the garden through the summer and early fall. The foliage will eventually die back as the plants go dormant for the winter. The leaves will start to deteriorate. This is the time to cut the stems completely off, near ground level. Dispose of the stems and leaves in the garbage. Do not compost peony leaves and stems, as they may attract botrytis (fungal disease), particularly in wet conditions. Clean up the ground area around each peony plant. Mulching peonies is not required in most areas. If you do mulch your peony plants, be sure to remove the mulch in the early spring to prevent the roots from being buried too deeply.
Peonies That Fall Down. How do I get my peonies to stand up like a lot or your varieties do? We explain that it’s mostly genetic. We select and grow a number of upright varieties that stand up through rains. We try to capture that in our peony descriptions. We also raise some of the gorgeous peonies that do benefit from staking. Their flowers are just too hard to resist. There are many herbaceous peony plants that stand up and hold their flowers high, including the Intersectional peonies (also referred to as Itoh peonies) that are absolutely upstanding peony plants.
Types of Peony Plants – What are bush peonies? Bush peonies are herbaceous, perennial plants. They are your common garden peony, growing stems and flowers each spring and provide nice foliage throughout the summer. Their stems are cut down to ground level late in the Fall. They are long lived plants and can produce flowers for decades.
What are Itoh or Intersectional Peonies? These peonies are a hybrid cross between a bush peony and a tree peony. They are also herbaceous, perennial plants, like the bush peony. They grow each spring, produce exceptional flowers, have lovely foliage throughout the summer and are cut back to ground level in the fall. The flowers and foliage are reminiscent of their tree peony parent, producing exotic flowers. Intersectional Itoh peonies are nice landscape plants, prolific bloomers and always upright – never needing staking. They are long lived plants and can produce flowers for decades. Many of the Itoh peonies have over 75 blossoms per plant at maturity.
What are tree peonies? Tree peonies have woody stems, exotic flowers (some with a crepe paper appearance) and lose their leaves in the winter. They can grow much taller and wider than herbaceous (bush or Itoh) peony plants.
Ants – Why don’t you have ants on your peonies? Again, it’s genetic and many of the varieties we’ve chosen don’t have the sweet substance that attracts ants. Some do. Some don’t. Contrary to old lore, ants are not required to open a peony. They are simply attracted to sweetness and good food, much like we are. You can control the ants if you wish, without affecting the health of your plant.
Transplanting Peonies from Pots (containers) - You mean I’m supposed to take the plastic pot off my peony when I put it in the ground? We have learned so much from our customers, and we appreciate the opportunities to slip in a little more information on how to grow peonies. Now, when we give the ‘transplanting a peony from a pot’ details to new peony gardeners, we start off with ‘Slip the peony out of the pot and set the plant in the ground with the top of the root ball sitting at ground level. Cover with just a bit of soil’.
Fertilizing Peonies – When and how often do I need to fertilize my peonies? This really depends upon your individual growing conditions. Many gardeners lightly fertilize their peonies and other garden plants annually, either early in the spring or in the fall. Many gardeners never or rarely fertilize their peony plants. We suggest giving ground planted peonies a bit of low nitrogen fertilizer (10-20-20) the first spring, to give them a boost. As they mature, you may want to skip a year and see how they do. You may discover you don’t need to fertilize annually. Never fertilize a potted peony with just ‘any old fertilizer’ - use a slow release fertilizer, or it will burn the leaves.
Leaf Spot – What can I do to prevent leaf spot on my peonies? Peony leaves and stems can attract Botrytis (a fungal disease that can produce a blight on stems, leaves or buds) during wet springs. The leaves will be spotted and buds may wither and die. Botrytis can be controlled or prevented by the application of fungicides. Choose a fungicide that is labeled for use on peonies. Organic fungicides are available. Prevention is key – apply the fungicide as soon as your peonies sprout and reapply according to the label instructions. Space your peony plants to allow for good air circulation between plants.
Peony Plant Care – What care do I need to give my peony plants? Peonies are rather carefree plants. Deadhead the flower heads after they are done blooming. Simply clip off the stem just under the flower head and tidy up the bush to a pleasing height. If you want to grow peony seed, leave some of the flower heads and collect the seed in late summer. The plant will spend energy making flower seed pods, so you may want to deadhead most of yours. In late fall, cut all of the herbaceous (bush and Itoh) peony stems down to ground level and remove them from the garden. Do not compost peony stems and leaves, as they might attract fungus. New stems will grow next spring.
Dividing Peonies – When do I have to divide my peonies? Maybe never. Peonies can grow in the same spot for years. Many peonies thrive for decades, without needing divided. Many of the peony plants in our iris garden/arboretum are over 25 years old and have not been divided. There are times you may need or want to divide a peony: to provide a sunnier location; tree roots have interfered with the peony roots; they have lost their vigor and need revitalized; or, you would like more of the same peony plants. Divide peonies in the fall.
Therese Sprauer, Brooks Gardens 2014