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Archive for the ‘Peony Propagation’ Category

Tree peonies are most often propagated by grafting or division. A third method is by branch layering. In addition to creating new clones, this technique can also be used to make for a lower growing tree peony with a spreading growth habit. Though tree peonies do not root as readily as most woody plants, if a living branch is buried beneath the soil, it will eventually form new roots. This may happen over one season or it may take several years. After the branch forms sufficient roots, it can be cut away from the mother plant. At Cricket Hill Garden, we have found that tree peonies with P. rockii genetics in their heritage root much more readily than tree peonies from other cultivar groups. If you want to attempt branch layering a tree peony, the best time to do it is either in the early spring before new growth commences or in the summer and early fall.

This P. rockii cultivar 'Black Tornado' is about 17 years old and now measures 11'' wide. We have achieved this spreading growth habit by layering branches.

This P. rockii cultivar, ‘Black Tornado‘, is about 17 years old and now measures 11 feet wide. We have achieved this spreading growth habit by pinning new growth to the soil so that they form roots and then send up new shoots farther and farther away from the original base of the plant.

A look at the base of the this plant

A look at the base of this plant shows how branches buried in the soil form roots and then grow new stems away from the original trunk of the plant.

It’s best to attempt branch layering on a tree peony which naturally has a lower growing or pendulous habit.

pendulous grower

This lower growing tree peony would be a good candidate for branch layering.

As a contrast, this tree peony has a much more upright habit. With only a few upright stems, this plant would not be an ideal tree peony to branch layer.

As a contrast, this tree peony has a much more upright habit. With only a few upright stems, this plant would not be an ideal tree peony to branch layer.

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The best branches for layering are vigorous with strong new growth.

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Remove three or four of the leaf stems on the area of the branch which will be buried. Be sure to leave the leaves on the top part of the branch which will remain above the soil.

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An optional step is to remove a patch of bark on the stem right below a new bud. During the summer, the bark on new growth will easily peel off. We have done many successful branch layers without removing the bark though some horticulturalists contend that removing the bark stimulates new root growth.

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Pin the branch 3 inches beneath the soil.

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After securing the branch, cover it with soil and water deeply so that there are no air pockets around the branch.

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Let’s check on a branch layer which we set up last fall.

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After digging away the soil, new white feeder roots are visible. This indicates that the layer has succeeded. If the purpose of this layer was propagation (rather than creating a spreading plant), this branch should be buried for another year before cutting it off from the main plant and replanting in a new location. This is because the root growth is not yet sufficient to support a whole plant.

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Dividing a Tree Peony

The principle method by which tree peonies are propagated is by grafting. This is a rather involved, labor intense procedure. Much simpler is to propagate your favorite tree peony by means of division. The technique used for this is similar to that for dividing herbaceous peonies.

Not all tree peonies are good candidates for division. Only those which are growing on their own roots will successfully divide. Tree peonies with only one or two main trunks should NOT be divided. Most likely a tree peony with this kind of growth habit is not growing on it’s own roots and is still reliant on a large grafted herbaceous peony nurse root.

Also, before deciding to attempt to divide a older, well established plant, remember that tree peonies are slow growing. It will take many years before divisions attain the grandeur of a mother plant a peak bloom. With that said, lets get chopping!

First, choosing the right plant to divide.

With only two main trunks, this tree peony would not make a good candidate for division. In this case it is even possible that the plant is not on its own roots and is still reliant on its grafted herbaceous understock. Attempting to divide a plant with this form my result in no viable divisions.

A multi-stemmed tree peony is a good candidate for dividing.

Notice many vigorous stems from the base. This is indicative of a spreading root structure.

Before digging up a peony, remove the leaves. Begin by digging around the drip line of the plant.

After loosening the soil a bit, remove some by hand from around the base. This will help to free the roots from the ground.

Dig around the plant some more. Be patient, good divisions are dependent on undamaged roots. Roots are easily broken by hasty and careless digging.

With enough soil removed, the plant should just ease out of the ground with a little gentle prying.

Quite a crater is left from the excavation!

The next step is to wash off the roots.

Since most tree peonies are grafted, its probable that even a very well established plant will still retain the original herbaceous graft root in addition to its own roots. In this photo both are clearly visible. The herbaceous graft root is dark and bulbous, while the tree peony roots are lighter in color as well as much longer.

We like to allow the plant to ‘rest’ for a few hours. We wet the roots and cover them with damp burlap. This allows the roots to dry ever so slightly and results in them being less brittle and thus less prone to break during the division process.

The two main tools you will need are a sturdy pair of garden snips and an large old kitchen knife. Be sure to wipe your tools down with isopropyl alcohol before beginning. This sterilization will prevent harmful bacteria and fungi from spreading via the cuts you will make.

If the herbaceous nurse root is still present, remove it before beginning the actual divisions.

The herbaceous peony nurse roots should slice off relatively easily.

Once removed, the old herbaceous peony nurse root can be discarded. Or you might try replanting it. Its possible that small, heretofore dormant buds will begin to grow on it. If you do this, expect to wait a few years before you see a flower from your new herbaceous peony.

Now you are ready start dividing. The first step is see where the plant looks like it might naturally divide. This allows you to visualize the cuts you will need to make. In order to be viable, a division must have both buds for above ground growth as well as adequate roots.

Look for naturally occurring divisions that seem to have both adequate stems and roots. Take special note of the new tree peony shoots coming up from the crown of the plant. Be careful not to damage these.

Its often best to initially try prying the plant in half. You may need to call a helper at this point.

A well placed snip will break through a shared piece of root.

The roots are very intertwined, so be careful and pull divisions apart gently.

One of the resulting divisions. It has a good stem to root ratio.

You may want to stop at simply splitting the plant in half, or you might opt to maximally divide your plant.

We have chosen to maximize the division of this rockii tree peony.

Further division beyond a simple split will probably require cutting through the hard, woody crown of the plant. Keep your helper around to help with this as well.

When you are satisfied with your divisions, clean them up. Trim ragged cuts and removed blackened bits of root.

To ensure that the above ground buds will not put too great a strain on the roots, we recommend trimming the top growth back by as much as 1/3.

In the case of very small divisions with little root, totally remove the woody top growth in favor of new, more vigorous buds.

The end result:

Three large plants, one medium, two small, one x-small and lots of scions to graft. Replant new divisions immediately. If the roots dry out, the plant will take longer to establish in its new location.

Dividing an older tree peony is not for the beginning gardener, nor the faint of heart. It is a given that the new divisions will take a few years of growth before the begin to flower well. In the end however, the result will be many more tree peonies to enjoy. Should you have any questions regarding this post, please do not hesitate to contact us.

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A few months ago we wrote about how to identify the herbaceous peony understock sprouting on a grafted tree peony.  This is usually the result of the grafted tree peony being planted too shallowly.  Now that the season for transplanting peonies has arrived, it’s time to dig up and remove unwanted herbaceous understock as well as replant the tree peony. It is necessary to do this because if left unchecked, the herbaceous peony can eventually overpower and choke out the tree peony. If you do like the way the herbaceous understock blooms, you can replant this and let it grow out.

If you have a tree-herbaceous chimera peony, now is the time to dig it up, remove the unwanted herbaceous peony suckers and replant the tree peony deeply enough so that it will grow its own roots on which it will thrive for many years to come.

Tree peony leaves are easily distinguished from those of herbaceous peonies. Tree peonies are dissected and three pronged, while herbaceous peony leaves are elliptical and pointed.

If you are unsure about the difference of the leaves, you can always check the stems. tree peonies are woody, while herbaceous are green.

Remove the leaves before digging up and peony. Dispose of these in a hot compost pile or outside of the garden least they spread harmful fungus throughout the garden.

The best method for digging up a large peony is to do it carefully. Being by digging around the circumference of the plant, about 18” away from the drip line. Then remove some of the soil from around the roots, lastly gently ease the plant out of the ground.

This plant had a smaller root system the anticipated.

The majority of this plants roots are herbaceous peony roots, it has very few tree peony roots. The herbaceous peony’s ‘eyes’ are the small white buds which have formed at the bottom of this year’s herbaceous stems.

Because this plant has so few tree peony roots, to remove all the herbaceous roots now would kill or weaken the tree peony. Best now to remove the herbaceous peony ‘eyes’ by trimming these pink or white buds. Replant the tree peony deeply so that it can grow its own roots over the next few years. Plant the tree peony about 4” above the graft union, or where the herbaceous peony roots begin. Take this opportunity to properly amend the soil for the tree peony. Place a shovel full or two of compost in the planting hole. As you back fill, mix in a cup of limestone dust if your soil is acidic. Mix in a few more shovel fulls of compost as you fill in the hole, mixing in a cup of Azomite to give the plant a mineral boost.

As you back fill, water in the soil/compost mix so that it settles well around the roots. Tamp down the soil and top dress with a shovel full of compost if you still have some handy. Newly planted, or replanted peonies should be mulched for their first winter in the ground to help prevent the soil around the roots freezing and thawing suddenly and heaving the roots above ground.

Tree peonies can be transplanted anytime now from now until early November in our USDA zone 6. The most important thing is to make sure that the roots do not dry out while out of the ground. Remember to plant in a sunny, well drained location, with rich soil and a pH of at least 6.5.

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The time for digging and dividing herbaceous peonies has arrived and can be done anytime through early November. Do you have a large, old herbaceous peony clump that you would like to propagate? The best way to do this is through dividing the root system. This is a form of asexual reproduction, and yields a duplicate of the mother plant. Many plants are propagated this way such as hosta, iris and daylilies. Planting the seeds from a favorite peony variety is sexual reproduction and this will yield new plants which may not share the same attributes as the mother plant.

Dividing herbaceous peonies is fairly straight forward process with an end result that will gladden any gardener; more beautiful peonies to spread around the garden or share with friends.

Digging up a herbaceous peony

By this time of year, herbaceous peonies are not looking their best.

First cut the stems down, but leave 8” of stem to aid in pulling the roots out of the ground.

Dig around the ‘drip line’ of the peony. For a large clump, this is at least 15” away from the center of the plant. We like to use a heavy duty fork, but a shovel will also do just fine.

Get your digging tool under the root system and gently pry. Do not be impatient to get it out of the ground. Take the time to dig around the clump a few times to loosen the soil and the roots.

Use the stems to ease the roots out of the ground.

Rather than pulling straight up, work it from the sides. Freshly dug peony roots are very brittle.

Dispose of old peony leaves outside of your garden. If you leave them to compost in the garden, any harmful fungi on the leaves will colonize in the compost and only spread further in the garden next year. Old peony leaves can also be burned.

Thoroughly wash off the root system. Cover with a damp towel or tarp and allow to sit overnight. This will soften up the roots and make the task of dividing much easier.

Dividing a herbaceous peony

Peony dividing tools and supplies.

Supplies:

  • Isopropyl alcohol and paper towels for sterilizing dividing tools
  • Garden clippers
  • Assortment of old knifes of various sizes; a paring knife and large cutting knife do well
  • Linoleum knife
  • Rubber Mallet

After letting your roots soften overnight, begin by cleaning up the remaining stems so you can see the eyes and how the roots intertwine. The ‘eyes’ are the bullet shaped pink buds which grow from the crown of the plant. Each ‘eye’ represents a stem and potentially flowers for next year. 

In order to grow well, a new division needs ample roots. Too many eyes with just a little root will be unbalanced and struggle to thrive.

Use the large knife with the aid of the mallet to make your first big cuts.

Make further cuts as necessary with a smaller knife.

After making your cuts, gently pry the pieces apart, carefully untangling the roots.

Cut off any roots with black spots.

Use the linoleum knife to further clean any lesions on the divisions.

Four new peonies out of one. These could be further divided, but we like to have at least 4 eyes per division, suggested minimum is two. New divisions may or may not flower the following spring, depending on the amount of root present. If there are flowers, most likely they will be significantly smaller than a the plant will produce after 2-3 years of undisturbed growth.

If all this seems a bit to much for you, there is the more primitive, but also effective method I like to call the “old farmer technique” of dividing herbaceous peonies.

Dig up clump.

Take good aim with a sharp shovel….

The results are not as precise but the process certainly more expeditious.

Now its time to plant your new divisions. Remember that the ‘eyes’ should be no more than 2” beneath the soil (shallower in warmer climates). Check back next week for a post on planting herbaceous and tree peonies.

‘Itoh’ or intersectional peonies are also propagated by division. Since the crowns of these hybrids are very dense and woody, its best to let them dry out for at least a day before attempting to divide.

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From late August to early October is the time to graft tree peonies in our USDA zone 5. Grafting is the most efficient means of reproducing a new clone of an existing tree peony variety. This is an ancient technique whereby the bud of the desired variety is fused onto an under-stock of either tree or herbaceous peony root. This nurse root serves as a ‘battery’ which powers the new growth for a year or two before it develops its own roots.

Cross section of a successfully grafted tree peony. This plant did not ultimately flourish because it was not planted deeply enough and the tree peony never developed its own roots.

One of the main reasons tree peonies remain expensive plants is that grafting, though a relativity labor intensive and slow process remains the most effective means of asexual propagation. Tree peonies reportedly can be rooted from summer cuttings, but success requires humidity and temperature to be carefully controlled. This is very difficult and not done in any production setting we are aware of. There have been some reports of success in cell tissue micropropagation of tree peonies, though large-scale success has thus far proved elusive. Age-old grafting techniques are the preferred method of propagation of tree peonies in Japan, China and the U.S.

Grafting will remain an essential skill for gardeners to propagate woody plants, as it has been for centuries. We present here a low tech method with little specialized equipment for those dedicated gardeners who seek to propagate their woody tree peonies.

Grafting tree peonies is similar to other kinds of grafting, but also differs in a few key ways. The following is the method we use at Cricket Hill Garden.

Preparing Tree Peony Scions and Herbaceous Peony Roots

Cuttings can be taken from tree peonies from late August through early October. In this period the buds have reached a good size and the stem have yet to become too woody.  Select large terminal buds for cutting. These cuttings are known as “scions”. Each scion should contain at least one terminal bud. If you can get a secondary bud as well, all the better.

Choose big terminal buds like this for use as scions.

After cutting your scion, trim off the leaves. Leave buds lower down on the branch to develop. Realize that in cutting the terminal buds, you are cutting off next years flower buds. This may be hard for any peony grower to accept, though a new tree peony may be of some compensation.

Leave secondary buds to develop for next year.

Trimmed tree peony scions.

If you are not going to do you grafting immediately, you can store the scions wrapped in a damp paper towel in a sealed plastic bag in the refrigerator. Scions stored in this manner should be viable for several weeks.

The best herbaceous roots are 2-year-old seedling which have been ‘decapitated’ of their ‘eyes’. Seedling roots are the most vital. If you do not have seedlings, a good healthy piece of root from any herbaceous peony will work very well. To obtain roots from a well established plant, you can either dig up a whole plant and cut what you need or extract a few roots by digging around the clump. For each graft you will need a 5-7” pieces of healthy and undamaged herbaceous root. Be sure that you keep track of the terminal end of the root.

2-year-old herbaceous seedling root which has been ‘decapitated’, or had its eyes cut off.

Large herbaceous root harvested from the side of a large clump. Note that we have cut the bottom end of the herbaceous root at an angle so we can distinguish it from the top

It’s best to pick and clean your herbaceous roots the day before you intend on grafting. Store them in a cool, damp place. This will allow them to become a bit less brittle and a little more elastic when you are ready to graft. Freshly harvested herbaceous roots can also be used but are quite brittle.

Tree peony roots, usually of ‘Phoenix White’ can also be used as under-stock. These are much more difficult to work with than herbaceous roots and are not recommended.

Before using your scions and roots soak them for 10 minutes in a 10% bleach solution. Then wash them off until they no longer smell of bleach, allow to air dry before begging grafting.

A quick 10% bleach bath before grafting helps to eliminate unwanted bacteria.

There are many different kinds of cuts which can be made to secure the tree peony scion to the herbaceous root. Make sure to sterilize your blades with alcohol before doing each graft. We will discuss the two which he have had good success with at Cricket Hill Garden.

Side Graft

Cut scion and rootstock at complimentary angles. Make sure that your cuts are on a level plain so that there will be good contact. The aim is to have the cambium layers of the tree peony scion and herbaceous understock match up. The cambium layer consists of the undifferentiated cells of the vascular system of the plant and is where growth occurs. In a successful graft the vascular cambia of the scion and rootstock grow together.

For a side graft, make one clean and even angled cut at approximately 45° to the scion.

Make a cut at a complementary angle on the herbaceous root.

The goal is to have the cambium layer of the scion and the rootstock match up.

Align the cambia of the scion and the rootstock.

It is not necessary to have the scion and rootstock be of the same diameter. If one is larger than the other, just match the cambium layers up on one side.

Tie up with rubber band. We use specialty grafting rubber bands, though a plain old office rubber band will also do.

Cover wound completely as possible, don’t worry if there is a bit of exposed tissue at the very top.

Wedge and Cleft Graft

This is a standard set of cuts and is perhaps an easier introduction to tree peony grafting than the faster side graft. Wedge and cleft grafting required four cuts. The goal here again is to match up the vascular cambia of the scion and the understock.

First, cut your scion with an even wedge.

Make sure that the two sides are as even as possible. We like to use a very sharp grafting knife or a  straight-edge razor blade for fast, clean cuts.

The wedge needs to have an even and clean bevel.

Then, cut a complementary cleft out of the rootstock.

Keep in mind that there is some give to the herbaceous root so the wedge should be narrower than the cleft.

The wedged scion should fit snugly into the cleft in the herbaceous rootstock.

Again, don’t worry if the scion and rootstock are of different diameters, just make sure that the cambium layers match up on one side.

Tie up the graft.  I like to tuck the tail in at the end and forgo tying a knot.

Tightly tied up.

Don’t futz around trying to get the scion and rootstock to fit just right. The Chinese say the excessive rubbing of the cut surfaces decreases the change of the graft taking. Better to practice making sharp, clean cuts before attempting grafts for the first time.

Even high volume commercial operations do not achieve 100% success in tree peony grafting. Our first year we had about 70% of our grafts come up in the spring, last year was lower, but that is because we began too early in the summer. Hopefully this year we will achieve 80-90% success.

Most tutorials on tree peony grafting have you cover the rubber band and wound area with grafting tape or polyfilm before setting aside to heal. We do not feel that this step is necessary because we heal the grafts for a short time at a high heat as opposed to a relatively longer period at room temperature.

Healing the Grafts

After you have tied up your grafts, they need to be healed. We have found the best way to do this is for a short time at a high heat. Place grafts in a 4” deep tray with clean, slightly damp sand at the bottom. The sand must not be too wet or the grafts will fail. Cover grafts with at least 1” of damp sand.

Be careful not to jostle the scions too much in fitting the grafts into a try of sand.

Keep the sand covered grafts at 90° F for six or seven days. We use a heat mat to do this. Ensure that the sand remains damp by occasionally misting the top and covering with a piece of plastic.  If the medium is too wet or too dry the grafts may fail.

We allow the grafts to heal for six or seven days.

After six days, the grafts will have ‘taken’ and the healing will have begun. We find that if the tree peony buds are still firm there is a good chance that the graft was successful.

Select a planting location which is has deep, well drained soil (pH at least 6.5) and receives about 6 hours of sun.

We use an iron breaker bar to make the holes in the garden bed  in which the grafts are planted.

Plant grafts so that top bud is 2-3” beneath the soil, space grafts 8” apart in 1′ rows.

Make sure that the graft is snugly planted with 2-3” of soil covering the top bud.

Mulch with a light layer of straw or leaves to help retain moisture. Right before or after the ground has frozen in the late fall cover your graft bed with a a layer of clear plastic and add additional mulch on top of this. We do this in November.

Mulch graft beds after planting to retain moisture. Cover with clear plastic and more mulch in the late fall, when the ground begins to freeze. Covering with plastic too early will invite mice to nest in your graft bed and ruin your results.  This has happened to us, so we warn you of this problem. Covered grafts are dormant all winter and begin to grow in the spring.

In the Spring…

Uncover your grafts by removing all mulch in mid to late March or when the crocuses bloom. The young shoots should be poking through the soil at this time.

Emergent tree peony graft in the very early spring.

Expect first year grafts to grow to 8-16”. Some may even form viable flower buds, though it is best to pick these off at an early stage so that the plant does not waste energy on a small flower. Begin to fertilize in the later spring after the leaves have turned fully green.

The amount of first year growth is contingent on a number of factors; ranging from scion and understock size to planting conditions and the relative vigor of a given variety.

This comparison illustrates the importance of using large and vigorous herbaceous roots as understock. These are both 1st year grafts of the same variety, the only difference was the size of the herbaceous root used as understock. Bottom line: the bigger the root the greater the strength of the ‘battery’.

In the fall of the first year, you may want to further space out your grafts. Space to 2′.  Remove rubber bands. If the graft has not developed any tree peony roots by this point, replant it deeper, at least 4” above the graft union.

1st year graft which has thus far failed to develop any tree peony roots. These are merely roots from the herbaceous understock.  It should be replanted above the first two buds.

                                    Grafted tree peonies which are not planted deeply enough often never

                                    develop tree peony roots and will fail to thrive.

2nd year graft with two vigorous stems. Most varieties will begin to flower in the 3rd year.

Supplies

Basic tree peony grafting supplies.

Sharp grafting knife or straight-edge razors

sharp gardening snips

isopropyl alcohol (to sterilize cutting instruments)

paper towels

rubber bands or hemp twine (specialty grafting rubber bands are available from nursery supply companies, but plain old rubber bands will also do)

herbaceous peony roots

tree peony scions (bud cuttings)

tray with damp, clean sand

heat mat (not strictly required, if there are other means of keeping grafts at 90 degrees for the healing period)

N.B.

‘Itoh’ or intersectional hybrid tree peonies can also be reproduced by grafting using the technique described here.

Tree peonies can also be propagated by means of root layering and division. We will be posting on these two techniques later in the fall.

In one of my first posts, I discussed experimental Spring grafting. Unfortunately all but one of these failed, though this could have been for a number of reasons. The scions were picked from winter damage and could have been dessicated, also the root stock was very small. Bottom line is that grafting is best done in the fall.

Some other links of interest on tree peony grafting

A good tutorial prepared by the Mid-west peony society.

An article by English peony grower Jo Bennison on tree peony grafting.

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Each year we collect seeds from our collection of Northwest Cultivar Group (rockii) tree peonies. You can order them from our website or send us $12 to receive 25 freshly harvested in late August. (Price includes postage.) We also have limited numbers of other peony seeds for sale. Please see our website for full information. Get your requests to us soon, we can only provide seeds a limited number of seeds each year.

Many of the seeds of Northwest Cultivar group p.rockii tree peony hybrids will yield plants which will produce these beautiful white flowers with maroon flares (blooming in about four years). This flower form and color is very similar to the wild species P. rockii.

Late August to early September will be the time to collect this year’s peony seeds. The vast majority of peonies yield viable seeds so if you left the pods on the plant all summer, try your hand at raising a crop of peonies from seed. Peonies raised from seed do not come true to the parent plant, though they may strongly resemble it. Almost all cultivated tree and herbaceous peonies are hybrids far removed from their wild species ancestors. The exception to this rule are seeds collected from a single species of peony which did not cross pollinate with other peonies.

Intersectional hybrid (Itoh) peonies are sterile and do not yield viable seeds. Unfortunately some garden favorites like the advanced herbaceous hybrids ‘Coral Charm’ and “Lois’ Choice’ are also infertile. Most of the European and American ‘lutea’ hybrid tree peonies like ‘Leda’ or ‘High Noon’ very rarely produce viable seeds. However, these are but a very small subsection of the peony world, the overwhelming majority of Chinese and Japanese tree and herbaceous peonies all yield large quantities of fertile seeds that will soon be ripe for the picking and planting.

Right now the beautiful star shaped pods are swelling and beginning to turn from a leathery green to brown in color. Seeds are ready to be harvested when the seedpod has turned a dark tallow-brown. We generally harvest our tree peony seeds here between the  3rd week of August and early September.

A good seed producing tree peony can yield over 50 seeds per pod.

The herbaceous seeds are ready a bit later, around the end of August.

An almost ripe herbaceous peony seed pod.

Methods for Seeding Tree and Herbaceous Peonies

When the seed pods have become a dark brown color and are just beginning to crack open, the seeds are ripe and ready to be harvested. Open up each segment of the seed pod carefully and remove the seeds. Damaged seeds will not germinate.

When fully ripe, peony seeds develop a double-dormancy which consists of a hard outer seed coat and dormant embryo. Germination occurs when air and water are able to penetrate the seed coat and reach the embryo.

There are many different methods for starting peony seeds. Some are determined by the natural condition of the seed, that is the level of dormancy while others are decided by the grower, primary weather to germinate the seeds outdoors or indoors.

Direct seeding outdoors

Freshly harvested seeds  may germinate in the same season (in the late fall) and sprout the following spring as a small green shoot above the soil. Directly planting dry seeds  with a hard and dry seed coat may need two growing seasons to naturally overcome the double-dormancy. These seeds shown below are harvested a little too soon. We have learned that it is better to wait to harvest brown and black seeds, otherwise the seeds will easily mold if not cured and somewhat dry.

Within each lustrous pearl is the germ of a peony which the world has never seen bloom, and has the potential to awe onlookers for centuries to come. Make the world a more beautiful place, plant some peony seeds this fall.

Left to mature seedpods will change to a dark brown and inside the seeds will change to black. The seedpods will also crack open. This is the time to plant the seeds.

 

Plant fresh (tan, brown or black) seeds directly in a sandy loam, garden soil mixed with a little extra sand, perlite or aged bark nuggets for drainage. The pH should be near 7.0, which often means adding some garden lime to sweeten the soil.  Either plant directly in a seed bed or use pots with good drainage holes, 10-12” in diameter.  We prefer clay pots or root control bags for seeding, though plastic pots will work.

Plant seeds about 1-2” apart, 2“ deep, and water well to settle in.  Seed orientation does not seem critical; the rootlet will find its way downward. At Cricket Hill Garden, we will sink the pot into the garden bed so it is protected in winter. Choose a site that is half sun, half shade. Cover over the seeds with 2-3 inches of mulch for protection from squirrels. If late summer and fall weather is hot and dry, water periodically to prevent drying. Normally, this is not needed after September in our climate. Later in fall, in late November, add 2-3 more inches of mulch for winter protection.

‘Root Control’ bags planted with peony seeds mulched for winter.

If conditions are right, the warm late summer weather will cause the seed to sprout and then cooler fall temperatures will promote root growth until the freezing weather. Nothing will show above soil level until next spring. Some seeds will not germinate until the second spring. Do not be impatient. We have given up on tree peony seed pots too soon, only to have them sprouting and growing in the compost pile! After two full years and 2 springs have past, and nothing shows, then likely you have a failure to germinate. This is often the case when you let the seeds dry out while germinating. So the first fall is very critical to have some  moisture in the seed pot.

Tree peony seeds sprouting in the early spring. These germinated in the fall.

Remove mulch from the pot in spring about two weeks after the ground has thawed, leaving pot submerged in the garden. Observe any new growth by May. Young sprouts need to be watered and fed a mild liquid fertilizer, such as Neptune’s Harvest fish-seaweed fertilizer every other month during the growing season, April to September. Young sprouts will be about 2” tall.

1st year tree peony seedlings in June.

1st year herbacoeus peony seedlings.

Move young seedlings ONLY IN THE FALL. Allow them to grow undisturbed until September of their first year.  After the first year space to about 6” apart in the garden.

In the second year tree peony seedling develop true leaves and grow to over 6” tall with foliage.

Young plants may be moved again in the fall season of their third year to a more permanent location. Allow at least 4 to 5‘ for each plant (3′ for herbaceous peonies) choosing a well drained site with 5-6 hours of sun for tree peonies. Tree peony seedlings will often start to bloom in their fourth year. While herbaceous will sometimes bloom in their third year. Keep in mind that peonies sometimes take several years of immature flowers before they show their mature form.

We have found this ‘direct’ seeding method very effective for seeds of  Northwest Cultivar group Chinese (P.rockii) tree peonies such as ‘Snow Lotus‘ and herbaceous peonies. Seeds from other hybrid groups of tree peonies may germinate more easy with the benefit of the steps described below.

GERMINATING FRESH PEONY SEEDS INDOORS

Open freshly harvested seed pods as described above. Instead of opening seed pods immediately after harvesting, some growers allow the pods to cure in brown paper bag for a week in your garage or a shady, dry area. After a week, carefully open the seedpods.

Place the seeds in a zip-lock bag of slightly damp fine sand or vermiculite. Put the bag in a warm place (around 80 degrees). We use the top of our refrigerator. Root growth may commence in 4-12 weeks, after which point the sprouted seeds (identifiable by protruding white rootlet) can be planted outside as described above or put in a refrigerator for a period of cold stratification of 3 months at 40 degrees (the vegetable crisper of the refrigerator is a good spot).

Sprouted herbaceous peony seeds. These can either be planted outside if its early in the fall or put in the refrigerator for a period of cold stratification.

Sprouted herbaceous peony seeds. These can either be planted outside if its early in the fall or put in the refrigerator for a period of cold stratification.

After this point the sprouted seeds can be planted in pots and either grown under lights indoors or gradually introduced to natural sunlight outdoors.   A note of caution, the protruding rootlet is very fragile, so handle with care when planting. If seeds fail to germinate after the first cycle of hot/cold stratification, repeat the three months of warm treatment (around 80 degrees) followed by 3 months at 40 degrees.

Peony seeds which have a black or dark brown in color and have a hard seed coat. If these seeds are planted outside without any special treatment, it will likely take two growing seasons for the right combination of water, heat and bacteria to beak down the seed coat and allow water and air to reach the embryo. We recommend scarifying the seed with a file or medium sand paper. Two or three passes is all that is needed to gently rub the seed coat. See the photos below.

Without special treatment, dry, black seeds need to go through a period  warmth and winter chill (either natural or simulated) before germinating.

In order to speed germination, the seeds can be scarified. This is a method of physically breaking down the outer seed-coat. We use a rather course file.

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Hold the seed between your thumb and forefinger and give it 2-3 light passes with the file.

About 2-3 light passes with the file is all that is required, filing too deep will damage the embryo. If you file the seed down to the point of the white interior, you have gone too deep. Filing so that you remove the outer seen if usually enough. It is only necessary to file a small section of the seed. A diluted solution of sulfuric acid can be used to scarify large batches of seeds.

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Filing just below the shiny exterior coat is all that is necessary to allow air and moisture to reach the dormant embryo initiate germination.

After scarifying, seeds can be planted out directly if its still early in the fall and the ground is workable.

If planting indoors, follow the instructions for warm/cold stratification in the section for planting fresh seeds.

Some other considerations regarding peony seeds:

  • Single, and semi-double flowers tend to yield more seeds than complex double forms.
  • Place in cold and dry storage if you are unable to plant right away.
  • Seeds collected from single specimen tree peonies (not in proximity to any other tree peonies) may not be viable.

Some of the beautiful tree and herbaceous peonies we have raised from seed. We call them our own Peony Heaven hybrids, but really we are just stealing the credit of the bees and the wind!

‘Zhou Dynasty Yellow’ herbaceous peony

‘Peony Heaven Celestial Peach’ herbaceous peony

New and as yet un-named Peony Heaven tree peony. Bloomed for the first time in 2011.

Another new Peony Heaven tree peony.

‘Post-Modern Phoenix White’ Peony Heaven tree peony

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Though we had a cold, wet inch of snow today, its safe to say that spring has finally arrived at Cricket Hill. Several male mallard ducks are jousting for the attention of a single female in the pond, and the tender emerald shoots of garlic are pushing up through the mulch.

This male mallard chased away three competing suitors

Garlic! I can taste the scapes already!

The tree peony buds are swelled and some of the early varieties of herbaceous peonies have their red eyes peeking out from the soil.

The buds of the later varieties of tree peonies have yet to break their calyx.

The early herbaceous variety ‘Coral Charm’ shows itself, the first herbaceous peony up this year!

With the blooming of the crocuses this past weekend it was time to uncover our tree peony graft beds. We uncovered several small beds containing a few hundred grafts. Because this week promises more wet and cold weather we have decided to wait on our main beds until things dry out this weekend. Last fall we grafted over 1000 tree peonies. I’m hoping for an overall success rate of around 80%. For our 2009 tree peony grafts our overall success rate was only 54%, but low number was the result of the total failure of a few varieties.

In 2010, we mostly used scions with nice fat primary buds. My preferred understock is 2 year-old herbaceous peony seedlings. After planting the grafts in August-September, I covered the beds with straw. Then in December I mulched with clear plastic and wood chips. No rodent damage was evident when I uncovered them.

Here is a graft a few days ago. Beginning to grow already!

And today, little peony babies in the snow.

It’s also time to uncover our seed bags. So much life!

Northwest Cultivar Group (P. rockii) planted last September.

Experiment in Spring Grafting

When the snow began to melt two weeks ago, we found that many of our most prized specimen tree peonies had suffered extensive winter damage. Many of our customers have reported the same. If you had a branch break on your tree peony, you should snip it off and allow the plant to heal. If there are other undamaged flower buds, these will received more energy and produce larger flowers this year. As long as the plant has a solid root system it will send up new growth this season to compensate for any that was lost this winter.

In addition to snow damage, for the first time in our two decades of growing tree peonies, some of our older specimen plants planted near stone walls were girdled by rodents. They totally gnawed off the cambium layer of the trunks, going up over 2′ in some cases. Aside for giving our cat an unlimited mandate to “disappear” as many mice and chipmonks as he can get his claws around, there was little we could do. With a heavy heart we cut down some of our most prized tree peonies.

This ‘Color of Eternity’ was over 15 years old and loaded every year with dozens of flowers.

This is was the little monsters did to it over the winter. I guess to be fair to them, they had no idea of knowing it was going to be such a harsh winter and only resorted to the peony bark as a famine food.

The branch is dead with the cambium layer so thoroughly stripped off.

I had to cut this plant almost totally to the ground, luckily I know it has a good strong root system and that it will be more beautiful than ever in a few years.

I spent a few days in merciless pruning of damaged branches, however I just could not bring myself to throw out all of that nice grafting material.

I collected these scions from damaged tree peonies as soon as the snow melted, hopefully preventing them from desiccating.

Tree peonies are traditionally grafted in the late summer and early fall, when the new growth has yet to turn woody and there is an ample supply of herbaceous roots available for use as understock. But, since I have good looking scion wood which would otherwise go into the compost why not try it in the spring?

The main issue seems to be that the cambium layer is very thin on last year’s growth as it is almost totally woody. However, some varieties seem more promising in this regard than others.

Cambium layer still looks pretty thick here.

Another issue is that I do not have a quantity of good herbaceous roots around now. What I was able to scrounge are small, so even if these grafts take, they will not be as vigorous as one done on herbaceous seedling roots.

Finished grafts.

I used hemp twine to tie them up, I have used jute in the past and it worked well. The advanatge of twine is that it will break down over the course of a year, unlike a rubber band.

I set the grafts in slightly damp sand at 90 degrees to heal. I will check them in five to seven days.

Transforming broken stems into new peony babies?????

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