Peony Culture...Solaris Farms

Solaris Farms™ 2010
Hardy Hemerocallis, Peaonia and Lilium

Herbaceous Peonies are one of the most easily grown hardy perennials available today. Long lived and durable, a peony can live easily as long as 100 years+. Most peonies in this group are of the 'Lactiflora' group, in other words they are selectively bred plants originating from the species P. lactiflora, which originates in China. Other species have been used with lactifloras to create hybrid herbaceous peonies. The hybrids are often more upright plants with larger more vibrant colored flowers. Both lactifloras and the hybrids are grown in the same way, have similar plant habits and needs.

Site selection is the most important factor in successfully growing any peony. Pick a place to plant the peony in which it will not need to be disturbed for a number of years and receives at least 6 hours of light and preferably full sun. Planting the peony too close to trees and large shrubs should be avoided since their roots will compete for water and nutrients. Herbaceous Peonies, like all peonies, prefer good garden soil that is well drained and has good amounts of organic matter. They can be grown in clay soils, and do quite well, provided it drains well.

Peonies do best when planted in the fall (for Wisconsin late August through October). The roots, which will have next year's eyes located on one end should be placed in a hole that will easily accommodate the roots. Squeezing the roots in to the hole could cause the peony to heave if surrounding soil is hard. It is best to plant herbaceous peonies with the eyes no deeper than 2" below the soil surface or the plant may not grow and flower properly. Most peonies are sold as bare roots in the fall and will have the stems cut off or removed. When planting we advise spreading the roots evenly throughout the hole and filling it two-thirds full of soil, then water to help the soil settle. Then fill the remainder of the hole with soil and water again. In another week or two come back make a slight mound over the plant, the mound will settle over the winter and your peony hole will not become a collection depression for water over the winter and spring. During the first winter it is also recommended that the peony be mulched so that frost does not heave it out of the ground in the spring. During the following years it is not necessary to mulch the plant for protection.

Many a gardener has been tempted to purchase the largest clump of peony they can find in hopes that the plant will flower the next spring. While the clump does usually bloom the next spring, it may not the following year and then go slowly into decline. The reason for this is that the plant needs room to grow new roots and this space is taken by large older roots that are storage vessels. There also appears to be a need to reset itself when being transplanted, thus the standard 3 to 5 eye peony is the best choice for long term performance.

Special attention should be given in the fall to cutting down herbaceous peonies and removing the stems and foliage from the area of the planting. Peonies can get a fungal disease called Botrytis, which shows up as black areas on stems and leaves during damp or wet weather. To avoid incubating this disease, through old foliage,

it is wise to remove foliage in the fall.

During the summer months peonies do not make much growth above ground, having done the majority of this work earlier in the spring. Old flowers can be removed, but allow the foliage to stay on the plant as long as possible. Peonies may look like they are doing very little during the hot days of summer, but they are busy storing food for the next year. The plants in our gardens remain handsome throughout the summer and make a nice green shrub. In autumn many of them produce leaves of gold, orange and red-adding to their value as a three season plant.

Fertiziling peonies can be done in the fall, but a soil test should be done if chemical fertilizers are to be used. High nitrogen fertilizer should be avoided as they will cause excessive plant growth without flowering. In most instances peonies need little fertilizing if the soil is good. Avoid planting peonies in places that have had peonies growing in them previously. Peonies utilize micronutrients in the soil that are depleted over time and planting them in depleted soil will produce poor plants.

Many of the hybrid peonies have strong stems and do not require staking or the placement of rings to keep them from flopping. The older lactifloras may need some assistance with support, but are well worth the effort. If you do not want to deal with plants that need support, ask or look at descriptions to avoid them.

The coral or salmon colored hybrids are often very fragrant, some might even say stinky. In any event they are excellent cut flowers and will certainly bring enjoyment to those gardeners interested in fragrance.

In summation herbaceous peony are outstanding long lived plants that will likely remain long after we are gone, given some basic care is provided. We have plants on our farm that were hybridized in the 1800's and some that were grown by my Grandfather in Brandon, Wisconsin. We enjoy them as much today as he did 50+ years ago.

Intersectional peonies are hybrids between a herbaceous peony and a tree peony. The plant habits are those of a herbaceous peony, but the flowers often

more closely resemble the tree peony. Intersectionals tend to grow very quickly and should be treated like that of a herbaceous peony. Cutting the foliage down, as herbaceous peonies are, is a good practice at season's end. Foliage can be somewhat intermediate between the two, but often is finely cut like the tree peony. Disease resistance is excellent and the plants often display hybrid vigor. This hybrid has been extremely difficult to hybridize from seed due fertility incompatibilities, therefore prices tend to be high-as is demand.

Planting is the same as for herbaceous peonies, but they may be planted somewhat deeper. A deeper planting tends to encourage new stems. A 4 inch planting from the top of the plant to the soil surface is usually a productive depth.

Some of the best varieties available are 'Bartzella'-yellow, 'First Arrival'-pink, and 'Viking Full Moon'-luminescent cream-yellow-pink blend. All are very hardy and as easily grown as herbaceous peonies in our cold Wisconsin climate.

Tree Peonies have been grown for centuries in China and Japan. In Japan they are referred to as 'Moutan' (Bouton) and in China 'Moudan'. They are among the most cherished plants in these nations and should receive much greater attention in American gardens. Many cultivars available are very historic hybrids that may be hundreds of years old, giving testament to their durability.

Shrubby woody plants, tree peonies don't actually fit the name commonly given to them. Most range in height from 2' to 4' and some can go to 8' or more. Many woody persistent stems typically make up a plant that usually spreads as much as it's height or greater. Tree peonies are generally very hardy plants that can be grown successfully in zones 3 to 7, but do best in zones 4 and 6.

Plant growth is relatively slow and it may take certain cultivars 3 or more years to mature into flowering plants. Often young tree peonies do not bloom true to form and will only show fully developed and colored flowers on a matured/established plant. Once plants are established they may grow in one place for in excess of 50 years.

Tree peonies are typically propagated by grafting a scion (stem and bud) on to a peony root (usually a herbaceous peony root). Grafted plants that are 3 years old usually begin to bloom reliably and have developed their own root systems. When purchasing grafted plants gardeners should watch for plants that have herbaceous leaves arising from their bases. If this very different leaf type is detected, the eyes of this portion should be cut away below ground so that it does not out compete the tree peony. Some tree peonies are grafted on to their own roots, which is most desirable. Division of tree peony roots is not typically an option since plants tend to grow off a centralized root system, but certain varieties are better subjects for this type of propagation.

Site Selection: A site that drains well and is not in competition with large tree roots in a must. The placement should get at least one half day of sun (preferably morning sun vs. afternoon sun) or bright filtered light. The plant would prefer full sun all day, but the flowers last longer with some shade. The soil should be loose and not compacted if possible. Soils with high organic material are most preferred, but clay works well if it drains. Gravel and sandy soils generally drain well, but are often missing nutrients important for tree peony growth. Soils rich in lime seem to be best and Eastern Wisconsin is well known for this (underlying limestone). Overly wet soils are probably a tree peony's worst enemy, in fact, a fairly dry location will suit the plant very well. Since tree peonies do not generally like to be disturbed, select a planting place that will accommodate the plant for many years without movement. Remember to allow plenty of space around the plant since in several years it could be large plant.

Planting: Start by digging a hole that will easily accommodate all of the peony's roots. Do not squeeze the plant into the hole, as the roots may begin to grow and push the plant out of the ground. Grafted plants should have the graft buried from 4" to 6" below the ground (or more), so that it is well protected from environmental changes. Tree peonies are best planted deeper than their herbaceous relatives-this often promotes growth from below ground and creates a more full plant. We've found that burying the root system to 6" or more will allow the stem to root quickly and branch below the ground. Many of our plants will have only an inch or less of stem above the ground after planting them! Fill the hole approximately 3/4th full of earth around the plant and water the soil thoroughly so that all air pockets are removed. Proceed to fill in the remainder of the hole with soil and add water as you fill. Lightly press down the soil around the plant with your hands once you have finished. Give the plant a couple of inches of mulching the first year to keep a more even temperature and moisture level around the plant.

Care: Generally tree peonies do not require much care after their first season. During the first winter it is wise to mulch the plant so that it is not moved around by spring freeze thaw cycles. We mound soil on top of our first year plantings in the field, this has proven successful in getting the plants through their first winter. Watering during very dry periods during the following summer may be needed until the plant's root system establishes itself. Once the plant is established very little care will likely be needed in the area of watering. If

watering is necessary during extreme drought, water the base of the plant not the foliage.

Tree peonies, like all peonies can get botrytis, a fungal disease which appears as black spots on the foliage or stems. Wet conditions can cause this fungus to be problematic and the best treatment is prevention, keep the plants on the dry side. If fungus becomes a problem, cut away all diseased parts and throw them in the trash. Commercial fungicides may also be used and a local garden center should be consulted (copper sprays tend to be most effective). Fall cleanup of the peony leaves is also a good method of avoiding this problem.

Fertilizing may be necessary at some point. Avoid high nitrogen fertilizers as this will cause excessive foliage to be made at the expense of flowering. It appears that tree peonies like limey soil with a PH from 6.5 to 7.5. A bit of agricultural lime sprinkled around the base of the plant has been said to produce better growth the next year. A soil test is a good idea you suspect that your plant is missing something nutritionally. A dressing of composed manure in a wide swath around the plant will do no harm and enrich the texture of the soil.

No winter protection on established plants should be necessary. A tall plant may loose stems from time to time during very cold temperatures, but new growth will arise from the base of the plant or below the ground. From time to time dead wood will need to be cut from the plant to keep it looking good. Do not cut down tree peonies in the fall like you would a herbaceous or intersection peony, since the woody stems carry next year's flowering buds. One exception to this would be if you would like more stems to arise from the ground. In this case, cutting the woody stems to the ground encourages dormant buds below the ground to grow into stems the following season and sometimes these will bloom their first season, but more likely the next season. We've used this tactic on plants that are in decline or have been slow to spread to the desired width.

The best transplanting time for Tree Peonies is fall, once next years dormant buds have been made. Roots on the plant are

being developed in late fall and early spring. Generally spring planting of peonies is not successful due to a lack of developed roots to supply the plant through the hot months of summer. Plants that do not outright die from spring planting, will often show extreme wilting during summer and a lack of growth. If they make it to fall alive, it is likely they will establish and grow the next year.

The hybrids are somewhat less cold tolerant than the Japanese and Chinese varieties, but can be successfully grown in Wisconsin in most locations. The species delavayii and lutea are tender here and are not easily grown.

In summation, tree peonies are a wonderful long term addition to a garden. Some patience will be required while the plant matures, but in the long run the plants will be extremely rewarding and will likely become one of the 'favorite' plants in the garden. Try one, you won't be disappointed.

William Seidl of Manitowoc, Wisconsin is one of our good friends and has kindly given us a great deal of guidance with these plants. He is well known in 'woody plant' circles and has produced excellent tree peony hybrids like 'Anna Marie'. His plants are becoming well known on a global scale and we hope that gardeners in Wisconsin will become better acquainted with them in the future. Many of Bill's registrations will be available through Solaris Farms as propagation successes are forwarded.