Posts tagged “rot

Tired Old Potentilla fruticosa

The potentilla that is the subject of this post was collected about 10 years ago by a friend of mine. I have admired this tree for some time, as potentilla’s of this size and drama are quite rare. When I had the opportunity to buy it for a reasonable price last year, I didn’t hesitate!

Potentilla fruiticosa yamadori

back

However, this tree has some serious issues and serves to illustrate some limitations of potentilla for bonsai. In a recent post, I said that potentilla are one of my favourite species. They are certainly not perfect, however. Many people will refer to the limited longevity of potentilla. While they are hard to kill, their weedy growth habit is subject to dieback. Their biggest issue, however, is wood rot. This tree is a perfect example of the issues that arise with potentilla over time.

When designing potentilla bonsai as a deadwood species, you must be very conscious of the soft wood. It is nowhere nearly as robust as the deadwood of other deadwood species such as Thuja and Juniperus, and requires extra care. This means treating at least once a year with a penetrating wood hardener, and keeping the deadwood clean and dry. This is the product I like to use.

These techniques were not applied to this potentilla over the last decade, and as a result it has lost much of its structural integrity as a result of rot. Some of the fine jins near the base of the tree also crumbled away when I first laid hands on the tree last summer. The tree is literally falling apart. To make things worse, was planted in a very mucky organic soil mix which takes a long time to dry out.

The purpose of this spring work was mainly to take steps to minimize the advancement of the rot by doing the following:

  • Remove as much of the rotted wood as possible
  • Bareroot the tree and replace the soil with a coarse inorganic mix
  • Plant the tree more upright so that the deadwood is far away from the soil surface
  • Treat with limesulfur, then wood hardener

Crevices such as this are highly at risk of rot, especially if they are not kept clean and dry.

This organic soil mix holds far too much water. This rotted the jins that (used to) lay on the surface and also creates too much humidity for the deadwood that lies above the soil. It is worth noting, however, that the tree grows fine in this soil. Potentilla will grow well in almost anything!

The video clip below shows the extent to which the rot has compromised the structural integrity of the tree.

 

This is the new pot. It is a yamaaki pot with some signs of age. It is far from ideal, but I think it is a slight improvement on the current pot. I think this tree is ideally suited to a crescent stone, but I have not been able to find the right one yet!

After much struggling, I decided to break the pot. The unusual shape made it very hard to get the tree out and, given how fragile the tree has become, I did not want to pry on it too hard. This pot was made by the previous owner and he warned me that I might have to break it - sorry! :)

Barerooted with the hose and trimmed. You can see that the root system is strong despite the difficulties the tree has presented to the bonsai design.

The tree is so "floppy" that it had to be tied to itself in order to achieve the desired angle. This guy wire is hidden at the back of the tree and can be adjusted if needed.

Thats it for now. Much cleaning and wood preservation still needs to be done, but I think that the deadwood is much safer now than it was before.

The back of the tree is quite interesting as well. As the structure of this tree continues to deteriorate, I am sure that I will have to keep other design possibilities in mind.