Potentilla fruticosa

New Pot for Potentilla fruiticosa

Quite a flamboyant choice. Perhaps too flamboyant? Well, it technically is a flowering tree… although it certainly doesn’t carry that presence.

Regardless, I find it a fun change.

New pot by Heian Kosen

New pot by Heian Kosen

 

Old Yamaaki pot. This pot couldn't handle the winter and developed some hairline cracks.

Old Yamaaki pot. This pot couldn’t handle the winter and developed some hairline cracks.


Some More Fall and Winter Images

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Tamarack

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American Beech (Fagus grandifolia). This species has stunning white-silver bark but it certainly isn’t the best beech for bonsai cultivation. This trio was thrown together for a demo in the spring. Not exactly a showstopper buy it is somewhat of a novelty in my garden. Needs a couple more trees and some adjustments.

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Tamarack

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Siberian Elm

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Potentilla. Not exactly known for their fall colour but this caught my eye as I was getting it ready for winter storage.

 

 


Potentilla fruticosa

This Potentilla is as fragile as a stained glass window and parts of it literally crumble away every time I work on it. It has undergone some pretty radical changes since I acquired it in 2011, and certainly does not look like the tree I initially envisioned it would become when I bought it. If I could give one piece of advice to anyone who wants to work with Potentilla – especially a deadwood specimen – I would say keep the trunk as clean and dry as possible. They are extremely susceptible to rot. Brush it, lime sulfur it, treat it with wood hardener, remove dead bark… all that good stuff is essential. 

The main things I did this year were to remove the last of the rotting parts, soak every piece of deadwood in lime sulfur then wood hardener, and compact the crown. I also completely redesigned the branch structure such that it is much more simple and “bonsai like”. This is contrary to the wayward, random nature in which Potentilla grow. I’m not saying the current image is better than some of the earlier ones. Certainly some incredible deadwood features have been lost.

Next step is to find the right pot, which certainly won’t be easy. I figure this tree still has a couple years of life before it returns to the dust from whence it came.

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The crown still needs a bit of filling out, but that won’t take long.

Earliest

This is the earliest image I have of the tree. I have no idea of the dates, but presumably the top left shows the tree soon after collection, while the other is the pinnacle of the tree’s development under its previous owner.

 


Overwintering Bonsai in the Toronto Area USDA Zone 5-6

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I’ve received quite a few emails from people asking about overwintering hardy trees outdoors. While there is lots of good information out there on the internet, most of it is region specific. What applies in England, Japan, or North Carolina does not apply in Toronto. With that in mind, this information is specific to zone 5-6 and is for people who have no special facilities (heated garage, polyhouses, etc.).

Reiner Goebel of rgbonsai.com has a good article about overwintering trees in the Toronto area. Have a read here. What I do is very similar.

  • Use tough species to make life simple. Semi-hardy species (Trident maples etc.) require more attentive care in this climate. My collection consists of Eastern White Cedar, Larch, Juniper, Yew, Siberian Elm, Potentilla, Ginkgo, and  few others. All fully hardy.
  • Don’t be afraid to leave them on the bench through a few late autumn frosts. They can take it. I usually put mine away in late October or early November. If the ground is frozen, you’ve waited too long 🙂
  • Bury the pots in the ground in your garden and water everything really well. This insulates the roots. The risk is not the rootball freezing. It can and should freeze solid. The tree will be fine. The risk is frequent freeze-thaw cycles. This is why unusually warm winters are more of a concern to us northern bonsai growers than unusually cold ones. Burying the pot helps ensure that once the rootball freezes, it will stay frozen until around March, even if there are some freakishly warm days in January (it happens). If your tree is in a massive training box but is a hardy species, just sit it on the ground and mulch around it. Just having contact with the ground will help buffer the rootball temperatures.
  • Snow is your friend. As soon as fluffy snow hits the ground, shovel it onto your trees (don’t shovel on heavy wet snow!). Sure, three feet of snow can bend branches but I feel most comfortable when my trees are buried in snow all winter. This protects from -20 degree air temperatures and drying winds. But when the snow starts to melt, brush it away as this heavy slushy mess can really cause damage to branches and fine ramification.
  • Try and winter them in a shady spot in the garden protected from the wind (i.e. a north facing corner). This provides a bit of insurance against wind and sun if it is a snow-less winter (like the infamous winter of 2011). It also helps keep the tree dormant as far into the spring as possible. This is important. If your trees break dormancy too early, the tender new growth will be exposed to the unpredictable early spring weather.
  • Rabbit-proof your garden as best as possible. When rabbits get hungry in the winter, bonsai bark apparently looks quite appetizing. Even  a couple of exploratory nibbles can ruin the image of a tree. Try to board up any gaps under the fence.
  • If you have the energy, fence in your trees with hardware cloth to provide further protection from pests. Burying the fence a couple of inches provides me some reassurance against mice, although if mice want to get anywhere bad enough, they will find a way.
  • Don’t worry about watering! If you put them away late enough, they should not need any water the entire winter.
  • Again, keep them dormant as long as possible. Don’t take them out of the ground at the first sign of spring in March. You know that in our part of the world it is not impossible to have freezing nights in May, and these spring freezes can kill off tender new deciduous growth.

This approach has worked well for me for 8 seasons. There are many ways to do it, but I find this to be the simplest and most foolproof approach. It takes some time to prep the trees for winter, but once they are in the ground you can literally forget about them, sit back, and wait for repotting season to come! Unfortunately, since the trees are frozen solid in the ground, you cannot really work on them in the heart of winter.


Another Potentilla

This one was repotted back in March and since then produced 2-5″ extensions, which were cut back today.

Also, some significant branches were removed from the apex. A new, lower apex will be built over the coming months.

Before apex pruning…

… and after.