Peony Questions Answered

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Q: I have a tree peony that is developing a large herbaceous peony in front of it.  My best guess is that the “graft” took, but also the herbaceous root has also been developing.
How is this resolved?  If I find it all on the same root system, how do I “operate” to save the tree peony without damage?   Should the two root systems look different?  I also think that its probably too late to dig at this time, so should I wait until next fall for better success?
Please help? 
CM in London, ON

A:  Tree peonies are normally grafted onto herbaceous peony nurse roots.Tree peony roots also works but they are less readily available. Some cultivated herbaceous peonies have the ability to form adventitious buds on roots well away from any crown tissue. Adventitious buds are those that develop where you would not normally expect to find them, the common example being roots growing from stem cuttings. Lactiflora cultivar roots rarely form these adventitious buds and so are commonly used for grafting. If your grafted tree peony begins to grow stems from its nurse root you will have to deal with it or risk losing the tree peony.

Grafted tree peonies must be planted with the graft union a few inches below soil surface, say about 4 inches. This will put tree peony stem in contact with soil and it must have soil contact in order to grow its own roots and develop crown tissue from which more stems will grow. This has implications in dealing with the nurse root if it ever starts growing its own stems because to handle the problem permanently you will have to dig up the entire plant and remove the herbaceous root portion at or above the graft union. The two types of roots should look different, but more than likely it will be very obvious where the union is. Often there is an enlargement at the union with the herbaceous portion having grown larger than the tree peony portion. Provided the tree peony has grown its own roots, separate the two parts on the tree peony side of the graft. If the herbaceous root has flowered and you want to keep it, you should remove the graft union from it too. If when digging you find the tree peony without its own roots, or with very little root mass, you may have to leave some herbaceous roots attached. This should not have happened if the peony was originally planted at an adequate depth.

Fall is the best time to perform this operation. September and October have nicer weather but I wouldn't hesitate to do it in November.

Alternatively you can cut down the herbaceous stems as they appear hoping to eventually weaken the nurse root, but that will be a long term effort and without the guarantee of the permanent solution afforded by digging and removal.  (Reiner Jakubowski)

Q: Where can I find a list of Canadian bred peonies?  Are there many Canadian sources? In my area, (Quebec) I know of only one place that has a nice offering, being Jardins Osiris.  Can I ask you suggestions for a lovely specimen? I personally favor the japanese forms? Is this a correct term?
A:   There is a list of Canadian bred peonies on this site. We have a list of Canadian suppliers on our website you can check out as well as this site.  There are many Japanese forms (yes, this is a correct term) to choose from:  Barrington Belle, Black Swan, Brides Dream, Bu-Te, Charles Burgess, Chocolate Soldier, Dai Jo Kuhan are a just a few.  (Margaret Sequeira)

Q: Why do the buds on my peony sometimes turn black and dry up early in the season?
A: 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 too 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.   (Lindsay D'Aoust)

Q: Why won't my peonies bloom?
A:  Peonies don't bloom because of cultural problems or disease. There are many possible reasons for the
         lack of flowers.
  • Planted too deep:  If the eyes are more than two inches underground, lift and replant.
  • 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. 
  • Too young, or moved and divided too often: Allow the plant more time to develop; it should be in the same spot for at least five years.
  • Large clumps transplanted without proper division:  Divide (3 -5 eyes per division) and replant.
  • Undernourished:  Buds form but don't develop.  Top dress with compost, avoiding the crown of the plant. Peonies will not flourish if soil is poor or competition from nearby shrubs and trees.
  • Over fertilized: Plants have deep green foliage but form no buds.  Water thoroughly to was away excess nitrogen and cut down on fertilizer.
  • Too much shade:  Plants will be tall and lanky; replant in full sun(6 or more hours) or part shade(4 to 6 hours). An hour or two less won't make much difference but heavy partial shade will reduce the likelihood of flowers.
  • Not enough moisture:  Water to bottom of roots.  (Established plants will bloom even when severely drought-stressed, although not profusely.
  • Root competition from neighboring trees or shrubs: Replant outside the neighbour's root zone.
  • Buds develop but fail to open: These may be damaged by late frost, disease, drought, or being waterlogged.
  • Root system undermined by gophers or moles:  Put in a wire mesh barrier around the bed.
Q: I have ants on my peonies what can I do to get rid of them? Will they hurt my plants?
A:  Ants do not affect the bloom or performance of your peonies.  They are attracted to the sap excreted from the bud.  Once the bloom opens you will find fewer ants.  Before bringing a cut bloom in hang your bloom upside down and give it a light shake to remove any unwanted hitchhikers. (Margaret Sequeira)

Q: My tree peony has grown new stems which have produced different looking leaves and blooms from the original plant.  What has happened, and what should I do about it?
A: When you see stems with foliage noticeably different from the tree peony's foliage, this indicates that stems are growing from the nurse root onto which the tree peony was grafted.  This happens for a couple of reasons.  The nurse root may have come from a plant that has the ability to grow stems from a piece of root, or there was some crown material left on the nurse root from which stems can eventually grow.  In both cases, the herbaceous stems will draw energy from the nurse root and chances are good that you will eventually lose the tree peony.  The herbaceous stems should be cut off as you see them appear, but a better solution is to dig the plant in the fall and remove the nurse root entirely, provided that the tree peony has grown its own roots.  (Reiner Jakubowski)

Q: Some garden centres and retail stores sell potted peonies in the spring.  I have read that the best time to plant peonies is in the fall.  Can potted peonies be planted in spring or must they be kept in the pot until the fall?  Are there any special instructions if planted early?
A: Plant a containerized peony as soon as you can get it into the ground.  If it is a herbaceous peony, try to disturb the soil around the root system as little as possible.  If the crown tissue is not exposed, plant it such that you maintain the same level in the soil. If, however, the root was too shallowly planted in the original container leaving the woody crown exposed, reposition the plant an inch or so below the soil surface such that the exposed crown is covered with an inch or so of soil.
Tree peonies are planted at the correct level.  Yours will likely need to be repositioned.  Carefully shake off the soil from the roots to see the graft point.  Replant the peony with the graft point 10cm below the soil line, 15cm would be even better.  Tree peonies are usually grafted onto sections of herbaceous root.  This herbaceous root sustains the tree peony only for a few years.  The tree peony needs to grow its own roots so tree peony wood must in contact with the soil.
When buying a containerized peony from a garden centre, ask when it was planted i.e. last fall or within the last few months.  A peony potted up in the fall is a better option than one potted up in late winter, early spring.  Though containers are not ideal growing environments for the bulky roots of peonies, at least those potted up in the fall have had the opportunity to put out some feeder roots.  This is not the case for those peonies potted up in late winter, early spring.
Summer can be tough time for a peony that has not had the benefit of fall root growth.  Peonies being the tough plants they are however, will usually recover.  They have suffered a set back though and will likely not establish as quickly as those planted in the fall.
In areas where the falls are very rainy and the summers cool, some gardeners have success with spring planting.  It is however a trade off between two evils; very wet falls that can cause rot in young plants and facing summer with few new feeder roots.  If the summer is cool the lack of feeder roots is less of a problem.
(Lindsay D'Aoust)

Q: I have collected peony seed in recent years, and would like to know how to tell if it is still viable.
A: There is no quick way to tell if the seeds are still viable so you just proceed as if they were.  I always handle seeds the same way regardless of where they come from or how long they've been lying around.  First I wash them with soapy water, then soak them in a solution of one part bleach, 9 parts water.  After rinsing them well, I soak them in water, sometimes up to a week, but change the water at least once a day.  This lets the seeds take up moisture.  Seeds that sink are considered okay, those that remain floating are probably hollow and if that's the case, they won't grow.  Once you start his process, you have to be prepared to continue it through the germination because what you've done is stimulated the seed to begin growth.  After the seeds are soaked, I put them into barely damp vermiculite in a sealed bag.  Milled peat moss works too.  Place them in a warm place, such as on top of the refridgerator, above the water heater in the basement, or any place where they will be warm.  After a week, some may be mouldy.  Throw those seeds out before the mould spreads to the others.  Keep checking and remove any others that become mouldy.  So, now you know which ones aren't viable, but I don't know how you could predict that otherwise.  Some seeds are so shriveled up that it's a pretty good guess that they'll never grow, but I have sometimes been surprised.  (Reiner Jakubowski)

Q: What is peony name registration, and how does one go about it?
A:Plants in cultivation are given identifiers, which in most cases are names but can also be coded numbers.  The objective is a unique name or epithet for each cultivar so that confusion between vendors and consumers, whether they e large agricultural businesses or backyard gardeners, is eliminated.  When you order 'Red Charm' you should get 'Red Charm' no matter from where in the world you order it.  A system such as this needs someone to control and oversee it, and so the International Society for Horticultural Science (ISHS)appoints International Cultivar Registration Authorities (ICRA) to be responsible for any given plant group in cultivation.  The American Peony Society is the ICRA for cultivated peonies.  Their website ( has a Cultivar Registration page where more information can be found.  Available is a down loadable Registration Form and a document which explains most of the items asked for in the registration form.  Peony names already in use and therefore normally not available can be found in the Peony Checklist.  The International Registrar for peonies can be contacted at
Essential in the registration process is that you must have a cultivar.  A single plant is not a cultivar, no matter how pretty or worthy it is.  You must first propagate it by appropriate means (in the case of peonies, by vegetative means) so that you have a number of identical plants that are shown to retain the desirable characteristics for which it was chosen.  A cultivar, a unique name, the completed registration form, photos showing plant and flower, and US$20.00 are the basic requirements for name registration.  Don't worry too much about all the details (which are found in the International Code of Nomenclature for Cultivated Plants).  The registrar will ask for nay important information you may have missed.  (Reiner Jakubowski)

Q: I am still quite a novice and feel that my expertise in the peony field leaves much to be desired.  My sister advises that when she transplants peonies from Spot A to Spot B, she has much better luck with them than many.  She claims that by ensuring that they continue to face the same direction when moved that they adapt much better.  Any truth to the concept?
A: I have never heard that orientation has any effect, and would expect that for herbaceous perennials it wouldn't matter.  Woody plants may benefit from being planted back facing the same direction as they were previously growing because there may be cellular differences between the side exposed to the sun, and the north side which gets less sun.  So if not orientation, then what might be the reason for better than average success?  A quick though on this is that we are dealing with a very careful gardener.  Anyone who is so careful to maintain the same orientation of the peony when replanting is probably also very careful in the entire digging and replanting process.  If the plant is young enough so that it is relatively small enough to move most of the root system, then you have a better chance of moving the thing without it knowing the difference.  Also a factor is the gardener's expectation of what constitutes "success", whether mere survival is sufficient compared to flowering right away in the following year without any set back at all. (Reiner Jakubowski)

Q: Last growing season, I left the seed pods on my Paeonia mlokosewitschii and noticed that they contained two colours of seeds, blue and red.  Is this a common occurrence in peonies and can both colours of seeds be grown with success?
A: Your plant of Paeonia mlokosewitschii is a species peony which means that it is the type found in the wild, and not one cultivated by humans.  Many of the wild peonies and a few hybrids have both red and either blue, blue-black, or black sees ( although Paeonia lactiflora in particular, has brown seeds).  The red ones are infertile, and the darker ones are the fertile ones.  So, if you are planting seeds, remember to avoid those red ones, or you will be disappointed! (Mary Pratte)

Q: Do the flowers of peonies change colour?
A: 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.   (Lindsay D'Aoust)