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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Plant exchanges and donations, Paeonia, Seed exchanges

Do you know of any plant and seed-sharing sites where I might find some peonies, for example? Or where I might post some stuff I have no place for?


Most reliable seed exchange programs require membership, but . . .

If you are interested specifically in peony seeds, the American Peony Society and the Canadian Peony Society are excellent sources.

You might also consider contacting the Pacific Northwest Peony Society. They are fairly new (est. 1996) and might not have a seed exchange yet, but can be helpful with other information.

The American Horticultural Society has an excellent seed exchange program (you must be a member to participate) for just about anything you could want.

There are several places locally that list plants for donation.
Plant Amnesty has an Adopt-a-Plant program. Also, try the Pacific Northwest Garden Exchange at GardenWeb.

This is a relatively recent phenomenon and many cities now have such programs. Here are some examples:
King County Seed Lending Library
Northeast Seattle Seed Library

There are groups on Facebook devoted to plant and seed exchanges. Be aware that not all of them are cautious about excluding aggressive or invasive species.

Date 2017-01-12
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Plant Answer Line Question

Keywords: Plant diseases--Control, Fungal diseases of plants, Paeonia, Plant diseases--Diagnosis

I planted some peony bulbs last year and they grew nicely until they reached about 10 inches high. One was in the ground, and the other is planted in a medium sized pot outside. The one in the ground is now dead, and the other one is not looking good. It gets dark spots on the leaves, and then the leaves die. Can you help?


Without additional details, it is difficult to say what may be wrong with your peonies. The Penn State Extension has information on different diseases that can affect peony plants. What you describe sounds somewhat like peony leaf blotch or measles, as shown in Iowa State University's Plant Pathology webpage on peony diseases. Here is an excerpt:
"Peony leaf blotch is also known as measles or stem spot. Warm, humid weather provides optimal conditions for infection by the causal fungus, Cladosporium paeoniae.
The leaf spots are glossy and purplish-brown on the upper sides of leaves. On the lower sides, spots are chestnut-brown. Infection is generally more pronounced at the margins of outer leaves. Leaves may become slightly distorted as they continue growing.
Fungal infections on young stems first appear as elongated, reddish-brown streaks. As plant growth continues, infected tissue near the crown may darken and become depressed. Stems on the upper portion of the plant may show individual, raised spots. To manage peony leaf blotch, cut the stems at ground level in the fall or early spring. Rake the area before new shoots appear. Fungicides are available to help control the disease, but must be used in combination with other management practices. Also, providing good air circulation and avoiding wetting the leaves when watering can help reduce disease severity."

There are other possibilities, including peony blight, also known as Botrytis blight. The Royal Horticultural Society discusses this problem:
"Peonies collapse at soil level and the stem bases are covered in grey mould. In a severe attack the leaves are also affected and the plant may be killed or so badly weakened it fails to sprout again next spring. Infections also occur frequently behind the flower buds just before they open.
This is a disease that affects both herbaceous and tree peonies. It is caused by a fungus (Botrytis paeoniae) related to grey mould (Botrytis cinerea), which may also attack peonies in a similar way.
Wilt is encouraged by high humidity which builds up around dense clumps of peonies. Increase the circulation of air by thinning out overcrowded shoots. Also avoid over-feeding, especially with nitrogen-rich fertilisers, which encourages lush, disease-prone growth.
Cut out all infected stems well below soil level, as soon as you notice them. Don't put infected material in the compost bin but burn it or put it in the dustbin, preferably in a sealed bag. If whole plants are badly affected lift and destroy them in their entirety along with the soil surrounding the roots. This total destruction is essential as the fungus can produce black resting bodies (sclerotia), which survive for long periods in the soil ready to re-infect new peonies.
There are no fungicides available to amateur gardeners at present."

I recommend taking plant samples to your local county extension agent for diagnosis.

Date 2017-02-16
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Plant Answer Line Question

Keywords: Cold protection of plants, Frost, Paeonia

I have two three-year old Tree Peonies - each in a 30-inch pot. Both have buds - what can I do to protect them from the coming freeze - or will they be ok? The pots are way too heavy for me to move. They are sitting on a blacktop driveway margin. I have no dirt to bury the pots into. Do I wrap them? Would bubble wrap work?

The new one I planted Sunday is covered with an inverted pot - will that be enough?


Your peony (Paeonia) buds will probably be fine, but don't take any chances! Protect the pots with bubble wrap and cover the tops with bed sheets or some other cloth. I think the inverted pot over your new plant should be sufficient. Tree Peonies are quite hardy. The frost would be much more damaging if it came in March or April when plants have leafed out.

Here is an article on predicting frost from Organic Gardening magazine.

University of California's Marin Master Gardeners also has useful tips on how to protect plants from damage by low temperatures. Tree peonies are not among the plants most liable to be harmed by the cold.

Date 2017-09-27
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Plant Answer Line Question

Keywords: Paeonia

I have a peony that failed to flower this year. What could be the cause of this?


Cindy Haynes of Iowa State University of Extension has a helpful list of possible reasons peonies may fail to flower. If there are no buds, it may be due to: not enough sun; recently transplanted; planted too deeply; too much fertilizer; need to be divided (clumps too big); plants immature; premature removal of foliage (in July or August). If they have buds that don't open, these may be the reasons: late freeze; other extreme weather; fungal diseases; insects; undernourished./p>

Another similar list of causes, from Ohio State University Extension:

planting too deeply
immature plants
excess nitrogen
inadequate sunlight
phosphorus and/or potassium deficiency
insect or disease problems
competition from roots of nearby plants
late freezes

Date 2016-12-30
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Plant Answer Line Question

Keywords: Wilt diseases, Paeonia

I purchased a bare root tree peony at the NW Garden Show this year and it was doing just fine, getting to be about 1.5 feet tall until about two weeks ago and the entire plant is now drooping, the leaves quickly sagging. It is in a semi-shady spot that receives morning sun. I water all of my plants once a day unless it has been raining. I am trying to figure out if it is dying, and what I might do.


My first thought is that your tree peony is either responding to drought, or too much water. My own tree peony which is about 12 years old has always been sensitive to excessive heat and drought. It is in a partly shady location, but it has root competition from two nearby conifers. Watering less frequently but more deeply is usually a good idea. A commercial peony site has the following information about this plant's water needs. Excerpt:

"Watering: This is the most common misunderstanding. Tree peonies do not have watering needs like roses or other perennials. They are woody shrubs native to northern China, which receives about 30 inches of rain per year. Once established, tree peonies are drought tolerant plants. Excess water will suffocate the roots and is the leading cause of plant failure. Do not plant near auto-sprinkler systems that keep the soils continuously moist. Do not water until soil is dry below the surface and try not to wet leaves when watering to prevent fungus. Be observant; soil can dry out on top and still be moist 6-12" below the surface. When you feel the soil is dry below the first 4-6" and leaves may droop slightly, water the roots deeply. Climates of hot summer temperatures with little or no rain at all will require more attention to watering then those areas that get some rainfall. Peonies in root control bags will require more watering attention than tree peonies planted in the ground. NOTE: Droopy leaves in the first warm days of spring are caused by an imbalance of the root system and leaf production. If soil has moisture, do not water. This imbalance that will self correct as the plant settles into the growing season. You know this is the cause of the limp leaves if the plant recovers in the evening or early the next morning."

The other possibility is a fungal disease called peony wilt. Here is more information about this problem, from the Royal Horticultural Society. Excerpt:

"Tree peonies can be vulnerable to attack by peony wilt (Botrytis paeoniae), especially during wet springs. Symptoms are wilting of the flower buds, sometimes accompanied by a fluffy grey mould and, later in the season, brown blotches on the leaves. Botrytis forms sclerotia (hardened fungal bodies) in diseased tissue, which carry the fungus over the winter, so it is important to prune out and destroy infected tissues to prevent this happening. Currently no fungicides labelled for control are available."

If you think that the problem may be wilt, and would like confirmation, you can bring samples of the leaves to a Master Gardener Clinic for diagnosis.

Date 2017-08-08
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Plant Answer Line Question

Keywords: Paeonia, Propagation

I have a tree peony that started as a seedling from a plant of a friend gave me 8-10 years ago. I would like to try to propagate mine from seed. From the little I've read, it seems this is a difficult process. Can you help me?


I believe you are correct that propagating tree peonies from seed may be a little challenging. It can be done, but home gardeners may find it easier to propagate by grafting, which is described by a link at the end of this answer.

The American Horticultural Society's Plant Propagation, edited by Alan Toogood (DK Publishing, 1999)rates seed propagation of deciduous tree peonies as moderate in level of difficulty. Another thing to bear in mind is that it will take several years before you see flowers on your new plants. In [late] summer, you would sow fresh seeds in pots and "provide two periods of chilling, such as two cold winters, with warmth between. Seeds are doubly dormant (roots emerge in the first year and seed leaves in the second). Guard against mice: they love the seeds."

Another description of propagating from seed may be found in Jekka McVicar's book Seeds (Lyons Press, 2003):

This seed has a double dormancy, producing roots in its first year and leaves in its second. It needs two cold periods, with warmth in between.

Collect ripe, fresh seeds in early autumn. Sow individually in pots, using standard soil-less seed mix, either peat or peat substitute mixed with coarse horticultural sand. Mix to a ratio of 1 part soil-less mix + 1 part sand. Cover with coarse grit, then place outside exposed to all weathers. Visible germination occurs during the second spring. Grow on in a cold frame for 2 years before planting out.

Excerpt on propagation methods from Plants for a Future database:

Seed - best sown as soon as it is ripe in a cold frame.When sown fresh, the seed produces a root about 6 weeks after sowing with shoots formed in the spring. Stored seed is much slower, it should be sown as soon as possible in a cold frame but may take 18 months or more to germinate.The roots are very sensitive to disturbance, so many growers allow the seedlings to remain in their pots for 2 growing seasons before potting them up. This allows a better root system to develop that is more resilient to disturbance.If following this practice, make sure you sow the seed thinly, and give regular liquid feeds in the growing season to ensure the plants are well fed. We usually prick out the seedlings into individual pots as soon as they are large enough to handle, and then grow them on in a cold frame for at least two growing seasons before planting them out when they are in growth in the spring.

The Heartland Peony Society has an illustrated tutorial on grafting tree peonies, should you wish to try this method.

Date 2017-05-24
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Plant Answer Line Question

Keywords: Planting time, Paeonia

I was given a tree peony in a container. It even has a couple of buds.

Can I plant it in the ground in spring, or must I wait until fall? How should I prepare the soil for planting?


Expert opinions vary on the importance of waiting until fall to plant tree peonies, or Paeonia suffruticosa. The Sunset Western Garden Book (2007) says "All peonies are best set out in fall", while The Gardener's Guide to Growing Peonies suggests that if peonies are planted in spring, the gardener must be very careful to water them well in dry weather that first summer. Of course, watering will still be an issue if your gift remains in the pot all summer! Also, this same source says in an excerpt:

Tree peonies usually become available in the early spring and...have small flowers. While it is very tempting to allow the plants to flower, this can considerably weaken a young tree peony. The buds are, therefore, best removed...and the shoot pruned to leave three or four leaves... Tree peonies are normally sold...in pots...with a peat-based compost. This is a suitable medium for transport, but the plants can deteriorate if they are not planted out fairly quickly into normal soil. ... In the autumn, it can be dug up...and planted correctly in its permanent home.

I don't know about you, but I wouldn't be willing to nip off those little buds! The "heeling in" practice, which involves planting the peony temporarily, might work though. Organic Gardening magazine has an article from which you can read an excerpt:

To heel them in, choose a sheltered, shady site and dig a V-shaped trench. Make the trench wide and deep enough to accommodate the plants' roots and long enough to prevent crowding. Place the plants in the trench at an angle, making sure the roots are below ground level. Refill the trench with soil (don't pack it down) and water the plants thoroughly. Check the soil moisture occasionally and water as needed. "You can leave plants heeled in for months, but I would suggest holding them that way only for a few weeks," says Amy Grotta, extension faculty in forestry education at Washington State University. "You don't want them to break dormancy before planting." Plants that come out of dormancy early are susceptible to frost damage, so plant as soon as possible to prevent harming your new purchases.

Directions for preparing the soil are very consistent in different literature: your tree peony will need a sunny site with rich soil, and "Tree peonies benefit from the application of a heavy layer of compost--particularly if they are grown in sandy soil" (says Martin Page in The Gardener's Guide to Growing Peonies). At least several days before planting, you should dig a hole at least one foot in diameter, and up to 3 feet in diameter, and amend the soil as needed in that planting hole. Unlike herbaceous peonies, tree peonies are planted 6 inches deep (that is, with the graft union 6 inches deep).

Date 2017-06-09
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August 01 2017 12:36:01