Frequently asked questions

Over the years I’ve been sent many questions about peonies.The following are some of the questions I get asked most frequently.

What is the difference between tree, herbaceous and intersectional or Itoh peonies?

Tree peonies have woody above ground stems that remain throughout the year, much like a small shrub. The leaves however are deciduous and fall each autumn.

Herbaceous peonies die back to the ground each autumn.

Intersectional peonies are the result of crossing herbaceous and tree peonies. Like herbaceous peonies they die back to the ground each year. Their foliage and flowers however are reminiscent of tree peonies.

All three types of peonies form the next year’s buds each fall. Tree peonies form these buds mostly on the above ground stems. Herbaceous and intersectional peonies form these buds on the underground crown of the plant. This difference accounts to a large degree in the difference in hardiness. Herbaceous and intersectional peonies will thrive in northerly climes too cold for tree peonies.

How many species of peony are there?

There is still some debate about the classification of peonies however depending upon the classification system used there are about 35 species.

The most well known species of peony is Paeonia lactiflora. This peony is sometimes referred to as the Chinese peony because of the extensive breeding work done by Chinese horticulturalists with this plant. The so-called old-fashioned double peonies are almost all cultivars of this species.

Why are my herbaceous peonies not blooming?

Peonies don’t bloom because of cultural problems or disease.

There are many possible reasons for the lack of flowers. The following are a few:

YOUNG PLANTS

Sometimes it can take 3 years to get blooms from a slow growing peony

SMALL DIVISIONS

When very small divisions are planted flowers take longer to appear. Divisions with 3-5 eyes will reach blooming size more quickly than the much smaller 2-3 eye divisions often sold in garden centres. We sell 3-5 eye divisions.

NOT ENOUGH SUN

With the exception of areas with very hot summers, herbaceous peonies generally prefer full sun. An hour or two less won’t make much difference but heavy partial shade will reduce the likelihood of flowers.

POOR NUTRITION

Peonies are heavy feeders. If soil is poor or there is too much competition with nearby shrubs and trees, peonies will not flourish.

PLANTED TOO DEEPLY

Divisions should be planted with the top eyes on the crown no deeper than 5 cm (2 inches).

DISEASE

Peonies hate growing in wet areas! Rot sets into the crown and over time the plant weakens. I have seen peonies hang in for years in poorly drained sites but they don’t flourish and eventually they succumb to the rot.

BUD BLAST

Young buds are attacked by a fungal pathogen or late frost and don’t develop

Why are ants always on my peonies?

They are hungry!

The ants visit your peonies because the flower buds secrete a sweet substance that the ants like to eat. The good news is that the ants are not harmful to your peonies! The ants don’t eat the actual plant and contrary to popular belief, the ants are not required to open the buds.

A small trick if you want to cut some of your peony flowers but don’t want to bring the ants into the house… Try cutting the flowers before they open and the ants get inside. Cut the flowers when the colour is showing and the bud feels like a marshmallow. At this stage it is easy to remove the ants and the buds will open nicely for you inside within a couple of days.

Can I grow herbaceous peonies in Zone 2?

Probably. It is certainly worth a try.

Paeonia lactiflora (the main species of peony) is actually native to Siberia. Some of the other species come from warmer climes and hence hybrids may be a bit more risky in your area though I would still say that they are worth trying especially if you have good snow cover.

When is the best time to plant peonies?

Fall

Peonies grow the majority of their roots in the fall. It makes sense to respect this growth cycle and allow newly planted peonies some time to grow roots before facing the heat of the summer. A peony planted in the spring will have endured the summer season with a less than optimal root system resulting in a stressed plant.

Peonies are tough plants though and many will survive the difficulties of spring planting. They do however seem to get off to a slower start.

Freshly dug peonies planted in the fall will, in my opinion, give superior results to peonies planted in any other season.

When will my newly planted herbaceous or intersectional peony flower?

Any where from the first spring after planting to up to 3 years after planting

How soon a newly planted peony division will produce flowers depends on at least 3 factors – division size, growing conditions and genetic propensity.

Good quality, fresh, large root divisions, planted in the fall will often send up a flower or two the first year. Smaller divisions can take longer to produce the first flower.

Growing conditions will always have an effect on flower performance. A peony planted in the right location at the right time will do better than one planted under less than optimum circumstances.

Some peonies however just grow slowly and they will take longer to establish no matter how good we are to them. The vast majority of our peonies however do not fall into this category.

How and when can I move an old herbaceous peony plant?

Dig and divide in the fall.

Peonies should only be moved in the early fall. It is however never a good idea to move a mature plant from point a to point b intact. The plant will do much better if, when you dig it up, you also divide it before replanting.

A mature plant that is moved without division is likely to just sit in its new location without flowers for some years. Newly planted divisions usually start vigorous growth immediately and will produce better quality plants.

You can find complete instructions on digging and dividing on the “propagation” page of our web site.

Are there any peonies that do not require staking?

Yes, there are many peonies that do not require any staking.

There is however staking and STAKING! I tend to classify our plants into one of three categories when it comes to staking. They are as follows:

CATEGORY 1 – NOT NORMALLY

These plants tend to be slightly less than average peony height, though there are notable exceptions, and have very upright stems. Many of them are early hybrids. Examples would be ‘Mandarins Coat’, ‘Dandy Dan’, ‘Paula Fay’, ‘Friendship’, ‘Horizon’, ‘Early Scout’, ‘Laddie’, ‘Illini Warrior’…

All the intersectional and tree peonies I grow fall into this category.

CATEGORY 2 – DEPENDS UPON LOCATION

No one wants to find the flowers on the ground but some people, myself included, prefer a plant with an informal look. These peonies tend to have a more open habit and have lots of movement. Very occasionally a flower will touch the ground but this is more the exception than the rule. Planted in an area that is not too exposed to winds and where they have a neighbour to lean on, they rarely require staking.

Peonies in this category that are planted in an open location with no neighbours to lean on benefit from some light staking.

CATEGORY 3 – LOOKS BEST WHEN STAKED

Some peonies just need to be staked either because their stems are very weak or their flowers are preposterously heavy. A good discrete peony support will keep these plants looking wonderful.

In the catalogue descriptions I try to indicate for almost all our peonies the staking requirements as I observe them here.

When do I cut down the foliage of my herbaceous peonies and how far?

Cut down foliage almost to the ground in the fall.

The longer you leave the foliage the better. But it should be cut back shortly after the first hard frost.

The leaves are used to produce food that is stored in the tuberous roots over the winter. This stored food supports the plant growth the following spring. By cutting back the foliage prematurely, the plant makes and stores less food.

A peony will likely survive an accidental chopping once or twice because they are so tough. However, foliage cut back very early in the season year after year will reduce the flowering performance of your plant.

The bottom line is that the leaves have a job to do and the longer they have to do it, the healthier the plant.

The foliage should be cut down to within about 5 cm (2 inches) of the soil level.

Note: The foliage is only cut down on herbaceous and intersectional peonies. Tree peonies are deciduous and the woody aerial stems should not be cut down.

Should I remove the flower heads once they are finished flowering?

It is a question of personal preference.

Many peonies, particularly the singles produce attractive seedpods after flowering and leaving them to mature only adds to the interest of the plant. Beware however that if you let the seeds fall to the ground they can become a nuisance weed.

Leaving the spent flowers is also the only way to obtain seed if you’re interested in breeding work.
On the other hand, many of the large double flowered peonies are sterile and the faded flower can be unsightly. In this case there is perhaps more reason to clip the faded bloom.

Why do the flowers on my new peony not look as I expected they would?

Your plants are probably young.

Young peony plants often produce atypical blooms during their first years. A double peony may actually produce single or semi-double flowers initially. The colour may also vary in intensity.

Peony breeders will rarely make a decision on a new variety based on the first years of blooming. It takes a few years for the plant to mature and settle down to producing flowers of typical form and colour.

Why are the stems of my herbaceous peonies rotting where they meet the ground?

A fungal pathogen has likely attacked your plant.

Peonies are susceptible to a number of fungal pathogens, especially in periods of cold wet weather. The problem could be attributed to Botrytis or Phytophthora, both of which are quite common in peonies.

The best treatment is to remove the diseased portions of the plant as soon as the damage is spotted. Be careful not to spread the disease yourself by handling diseased plants then touching healthy plants.

The plant will likely recover on its own as long as the attack is not too widespread. Be careful this fall to remove all dead peony foliage from the peony bed. This will help ensure the problem does not return next year as the fungi over winter in the foliage. Good air circulation around the plants will also help reduce the incidence of fungal diseases.

In my experience, good fall clean up and good air circulation go a long way to reducing the incidence of fungal diseases in peonies.

Can I grow peonies in containers?

Yes, but success will require a certain amount of special attention.

A FEW THINGS TO TAKE INTO CONSIDERATION:

  • Peonies have very large root systems, and even more so for herbaceous and intersectional peonies.
  • Impeccable drainage is imperative
  • Peonies are heavy feeders
  • Peonies require an extended period of cold to overcome late season dormancy
  • Exposure to a deep freeze can destroy the peony root system
  • Peonies are best planted in fall, which is when they make the bulk of their new root growth.

Success with peonies in containers will depend on how large a container you can provide and what winter conditions are like.
Peonies in containers exposed to deep-freezing temperatures will likely not survive. Low temperatures however are required if the peony is to overcome seasonal dormancy. Hence success will depend on finding the right balance.

I wouldn’t for example leave a peony in a pot on a balcony in Montreal over winter. It would have to be placed in an area with near freezing temperatures for the duration of the winter.

Peonies are heavy feeders so any container mix will have to take this into account. Drainage however must be excellent otherwise root rot will set in.

Dark coloured pots absorb much heat during the day and this can also have an adverse effect on a pot grown plant.
There is no universal tried and true method of growing peonies in pots. You will need to experiment to find what will work in your conditions.

Generally it is easier to achieve success with tree peonies than with herbaceous and intersectional peonies just because the root system of a tree peony is smaller.

Can I grow peonies in a warm climate?

The short answer is a qualified yes.

Having always lived in northern climes I can’t speak from personal experience, however peonies are generally considered to grow well into USDA Hardiness Zone 8.

The factor limiting the success of peonies in warm climates is the requirement for a cold period to overcome a seasonal dormancy. There is no well-accepted data available that states exactly what the requirement is in terms of temperature and duration.

There does however seem to be consensus that weeks of freezing temperatures are not required. There have been several reports from gardeners in USDA Hardiness Zone 9 who have grown peonies successfully.

Peonies grown in warm areas will benefit from slightly more shade than those grown in cooler climes.

Paeonia lactiflora comes from the most northerly locations and as such is logically less likely to perform well in warm areas. The early flowering herbaceous peonies tend to be either hybrids or varieties of species from warmer areas. These are likely best suited to warmer areas.

Tree peonies are probably the least stringent of all the peonies in their cooling requirements and are a good place to start experimenting if you live in a location warmer than USDA Hardiness Zone 8.

How do I prepare my herbaceous peonies for winter?

Cut down the foliage and remove it from the bed.

As a rule of thumb, it’s time to cut down the foliage anytime after the first hard frost or by the end of October in warmer areas. It’s also a good idea to remove the foliage from the peony area as it can harbour fungal pathogens such as botrytis that can attack peonies in cold wet weather.

What are the most fragrant peonies?

Generally speaking double herbaceous peonies are more fragrant than single herbaceous peonies. And, the pinks are more fragrant than the reds. White double peonies also tend to be fragrant. There are however lots of exceptions!

We grow a few double pinks that are not at all fragrant and I have one wonderfully fragrant double red, so beware of exceptions.
Many singles have a light fragrance but I find they are rarely as powerful as the doubles.

The early herbaceous hybrids tend to have little or no fragrance.

Some of the intersectional peonies have a very good fragrance. ‘Garden Treasure’ being an example.
I have yet to find an exceptionally fragrant tree peony but many have what I would consider a good fragrance.

What is the “fern leaf” peony?

Paeonia tenuifolia and its varieties.

The term “fern leaf” peony is often used to describe a specific species of herbaceous peony namely Paeonia tenuifolia. This species has very distinct soft almost needle like foliage with single red flowers. The most popular “fern leaf” peony however is the double flowered variety P. tenuifolia ‘Plena’.

P. tenuifolia flowers very early in the peony season and is a good choice for the rock garden or the front of the border because of its diminutive stature – 40 cm (16 in) or less.

A disadvantage of these peonies is that the foliage tends to go dormant and die back earlier in the season than the more well-known lactiflora peonies.

Are there any peonies suitable for a rock garden?

Definitely!

The most frequently mentioned rock garden peony is probably P. tenuifolia ‘Rubra Plena’ or the so called “fern leaf” peony. Here we grow several P. tenuifolia hybrids (‘Little Red Gem’, ‘Early Scout’, ‘Laddie’, ‘Smouthi’, ‘Merry Mayshine’) that are very well suited to rock gardens and there are certainly others that, because of their delicate form and low height, look great along with a number of alpines.

These hybrids have very dissected foliage similar to but perhaps a little wider than their P. tenuifolia parent. The flowers are single, red and some have a pleasant fragrance. I prefer the hybrids to the species because they make a neater plant and keep the foliage longer during periods of hot dry weather. They range in height from 30 to 90 cm (12 to 36 inches).

Can I plant herbaceous peonies in a shady location?

It depends on your local climate and the type of shade.

I have found that peonies do best in full sun in my area – southern Québec. However in areas that have very hot summers, some high afternoon shade can be beneficial.

Also, in areas that are prone to late spring frost, some early morning shade is helpful in reducing frost damage to flower buds. Frosted buds seem to survive the experience better if they warm up slowly.

When discussing shade tolerance it is very important to note that all shade is not alike. I would suggest that if you are considering planting peonies in an area that does not receive at least 6 hours of full sun, you experiment with a couple of plants before investing too much money in plants that may not flourish.

Tree peonies and some species peonies such as P. veitchii will tolerate, and actually benefit from, more shade than the herbaceous and intersectional peonies.

Shade certainly has its advantages. Light shade maintains flower colour better than full sun and pale flowers always seem to look more luminous when grown in shade. The trick is to find just the right balance between sun and shade!

Do the flowers of peonies change colour?

Yes and no…

Young plants take time to mature and they often produce flowers that are not the same form or colour as those seen on mature plants of the same variety. As the plant matures however the flower form and colour stabilizes.

Weather can also affect to some extent flower colour, especially the lighter coloured flowers. A cool damp spring seems to make the whites a little less brilliant and any pink tinges become more accentuated.

Can a white peony become a red peony? I don’t believe so. Judging by the number of times I get asked this question though, some people are seeing red flowers where white ones used to grow and vice versa.

One possible explanation for such a radical change is that a peony seed has germinated on top of the original plant and over time has taken over the location. The flowers that the owner now sees are those of a different plant growing where the old plant once stood.

The foliage on my herbaceous peonies was accidentally cut down right after flowering. Will my plants come back next year?

Yes.

A peony will likely survive an accidental chopping once or twice because they are so tough. However, foliage cut back very early in the season year after year will reduce the flowering performance of your plant.

Are there any truly yellow peonies?

Yes.

The only truly yellow herbaceous peony is the very rare wild species P. mlokosewitschii, sometimes known just as Moloko or Molly the Witch.

There are a few other herbaceous peonies that are often described as having pale yellow flowers e.g. ‘Prairie Moon’, ‘Goldilocks’.

The big news in truly yellow peonies is the so-called Itoh hybrids or Intersectional crosses. These plants represent crosses between herbaceous and tree peonies.

Though first achieved in Japan in 1948, American peony breeders have also introduced such Intersectional peonies as ‘Bartzella’ and ‘Garden Treasure’. These two peonies have unmistakably yellow flowers. Beware however that the price tag on these plants is high. In 2015 ‘Bartzella’ and ‘Garden Treasure’ could be found for $120.

Yellow is a fairly common colour in tree peonies. At the end of the 19th century Father Delavay collected seeds of the yellow flowered tree peony P. lutea in China. These seeds were sent to France where French hybridizers Henry and Lemoine crossed the resulting plants with tree peonies from the suffruticosa complex. Many of the resulting hybrids were yellow. ‘Souvenir de Maxime Cornu’ was the first such hybrid and can be found in this year’s catalogue.

American breeders such as Professor Saunders and Nassos Daphnis also worked with P. lutea to create a number of beautiful yellow tree peonies.

Can I grow peonies from seed?

Yes.

Many peonies are fertile and do produce seeds. These seeds can in turn germinate and produce new plants. With the exception of wild species populations however peonies do not come true from seed so growing peonies from seed is not a way to obtain more plants of your favourite variety.

Growing from seed however is the way to discover new peonies. Each seed will produce a “new” peony with a high probability of not being like its parent. It may be wonderful, but there again it may not! The only way to find out is to germinate the seed.

Peony seeds collected from species peonies in the wild are likely to yield plants similar to the parent because all the peonies in the area have a very similar genetic makeup. Often growing from seed is the only way to obtain plants of many species peony.

Should I apply fertilizer to my peonies?

Not necessarily.

Peonies are heavy feeders but whether or not additional fertilizer is necessary depends on the type of soil. Heavy soils tend to be more fertile than sandy soils and it is not always necessary to add fertilizer. Sandy soils however tend to be nutritionally poorer and the regular addition of nutrients will help ensure the peonies are well fed.

In my opinion these nutrients are best added in the form of compost rather than chemical fertilizers. Top dressing around your peonies each fall with well-aged compost will improve the structure as well as nutritional content of the soil. It is best not to add the compost directly on the crown of the peony, but rather in a circle around it.

If compost is not available, a granular fertilizer higher in phosphate and potassium than nitrogen can be scratched into the soil around the crown in early spring and fall.

We have a special occasion to celebrate a few weeks after the peonies are normally finished blooming. Is there any method to store the blooms?

Yes, cold storage holds blooms well.

Cut double blooms just before they are fully open. Singles and semi-doubles should be cut before they open at all and when the bud is showing colour and is quite soft to the touch. Remove the leaves and place them in about 8″ of water in the fridge. Cut blooms keep quite well in an old refrigerator for several weeks.

It takes a bit of experimentation to know exactly the right time to cut each variety but it is certainly possible to hold peonies for at least 3 weeks, if not more.

Do peonies require a specific type of soil?

No, for the majority of peonies.

Most peonies are tolerant of most soil types. However, they are heavy feeders and must be in a well-drained location.

Clay soils are generally very fertile but drainage can be a problem. Because clay is so dense, water does not always percolate through it quickly. Peonies hate to have water standing on their crowns. In fact, poor drainage is probably the number one enemy of a peony. If you can ensure good drainage of the peony bed, they should do well in clay soil.

When growing on lighter sandy soils, soil amendments such as compost may be necessary to maintain soil moisture and fertility.

Species peonies can be less tolerant i.e. they have a narrow range within which they will flourish. Unfortunately these tolerances are not always well documented and growing them can become a learning experience.

Publications by the Canadian or American Peony Societies can be useful places to find gardeners exchanging their experiences with these peonies.

How are herbaceous and intersectional peonies propagated?

The usual way to propagate herbaceous peonies is by dividing the underground crown in the fall. This vegetative method of propagation will result in new plants identical to the original peony i.e. clones.

Some peonies produce seed but the seeds will not produce plants like the parents i.e. each seed will produce a new and unique peony. The only exception being in wild populations were pollination has been controlled over many years. Growing peonies from seed is however an important part of a peony breeding program.

The “propagation” page of our web site gives detailed descriptions on how to grow peonies from seed and how to divide mature plants.

How are tree peonies propagated?

Grafting.

Tree peonies are generally propagated by grafting a scion, or small length of tree peony wood, onto a section of herbaceous peony root. The herbaceous root supports the tree peony wood until it can form its own roots.

How long do peonies live?

When peonies are growing under optimal conditions it is not unrealistic to expect them to live for over 30 years. Not many herbaceous plants can boast such longevity!

There are peonies growing in my mother-in-law’s garden that have been in the same location for over 50 years. Other than cutting down the foliage each fall, they receive very little attention but every year they produce masses of flowers.

Do I have to divide my peonies regularly as I do iris?

No.

Peonies do not need to be divided periodically. On the contrary, well-established peonies do not like to be disturbed. If however you have to relocate a herbaceous or intersectional peony it is always better to dig, divide and replant rather than transplant the entire plant from one location to another.

Mature tree peonies are best left in the same location.

How far apart should peonies be planted?

From 75 cm to 1.5 meters (2.5 to 5 ft) centre to centre depending on the variety and look you want to achieve.

Peonies look great as specimen plants as well as in groups. Typically I plant peonies on 1-meter (3 foot) centres. I would not plant peonies much closer than 75 cm (30 inches) centre to centre. This minimum spacing ensures some air circulation and not too much root competition. Some varieties however grow quite wide ex. ‘Postillion’, ‘White Innocence’ and a wider spacing would be advisable.

I generally would not plant tree peonies any closer than 1 meter centre to centre.

What are the reddish brown spots on the leaves of my peony?

Likely the result of a fungal infection.

Peonies are subject to a number of fungal diseases that tend to thrive in cool, wet weather. There are several fungi that could be the cause of the problem but I would guess that it is due to Cladosporium or peony measles. This fungi is often seen after flowering and it attacks the leaves and stems. The spots start out as small red lesions (hence the name measles) and eventually coalesce into dark necrotic spots.

Cladosporium will not likely kill your plants. It is a good idea however to cut down the foliage around the time of your first hard frost and remove it from the garden.

Why do the buds on my peony sometimes turn black and dry up early in the season?

Likely the buds have been damaged by frost or a fungal infection.

What you describe is often called bud blast. It can be caused by environmental conditions at a critical stage of development such as frost or drought. It can also be caused by a fungal attack, usually during cold wet periods. In these cases the problem is unlikely to be repeated the following year and the plant will likely continue to thrive.

If the problem happens next year you might also suspect a nutritional problem, likely not enough potassium, too much shade or that the plant is planted too deeply. All of these are correctable by either adding fertilizer or moving the plant to a more suitable location in the case of shade or planting to deeply.

Bud blast often occurs in newly planted peonies. Peonies form their buds in the fall. If a plant is divided and replanted in the fall (as it should be) the previously formed buds will continue their growth in the spring on a much-reduced root system. Often the newly divided plant does not have the “strength” to fully develop all the buds and they just dry up. As the plant matures this problem disappears.

Is it true that peonies planted too deeply will not flower?

Yes and no.

Herbaceous and intersectional peonies should be planted such that the top most buds on the crown are about 5 cm (2 inches) below the soil. A newly planted peony will always grow to position itself at the right level. The depth of 5 cm (2 inches) is a good safe starting point. Too shallow and the crown risks being damaged by winter weather or careless cultivation. Any deeper and the plant will spend valuable growing time reaching the right depth rather than producing flowers.

Planting a herbaceous or intersectional peony at 10 cm (4 inches) rather than 5 cm (2 inches) will just mean you will wait longer for it to flower. If the poor plant is positioned at say 20 cm (8 inches) below soil level, it may never manage to struggle to the right level.

Tree peonies are different. Because they are grafted and because we want them to eventually grow on their own roots, it is important that several inches of tree peony wood be in contact with the soil even if this means almost entirely burying the young plant. The graft union should be a minimum of 10 cm (4 inches) below ground and deeper is better.

How can I find out the name of a mystery peony I have in my garden?

Identifying so called “mystery peonies” is very difficult! However some people are trying to put together some tools to help gardeners identify their peonies.

The Heartland Peony Society in the US has an extensive gallery of photos that can be helpful.

If you have a peony to which you’re trying to attach a name, it’s not enough to know that it is a pink double that flowers in June. During the growing season try to make detailed observations about such things as plant habit, flower form, fragrance, stem colour, leaf colour, overall height, does it set seed, are the carpels (seed pods) visible, are there any pollen bearing stamens, are the stems hairy, bloom time in relation to a known variety ex. 3 days after ‘Red Charm’ etc.… The more information you collect the better the chances that a match will eventually be found.