Creating an exposed root
This started a while ago. A few Swindon club members collectively agreed they appreciated the exposed root style of bonsai while we were at another club’s show. We made a pact to have a go at creating one for ourselves, myself included. This is as far as I got Terry. I mostly work with pine so it wasn’t difficult to make a decision of what species to use, for me. This is a good example of an exposed root Azalea at Lodders Bonsai, NLI wasn’t sure what techniques were used to create this, and to be honest I was more interested in trying to engineer a solution myself. I got to work using a sapling I had been growing for a few years. This Japanese black pine (Pinus thunbergii) had already been wired into a loose shape. You may be able to see from the image I removed the wire on the trunk later so as to mark & compress the base of the plant, this thickens the trunk as a response, later down the road (hopefully). The sapling health was good when first potted up, you can tell by the dark green colour of the needles. My solution was to plant in a large diameter downpipe. I filled it with 50% Akadama + 50% Kiryu. Larger medium down the bottom for better drainage; smaller at the top. A chopstick was used to ensure the soil would not collapse. One problem with using this pipe; keeping it upright. I tried cutting up and using a couple of plant pots but this didn’t really work. Too top heavy and liable to fall over in the wind. I ended up planting all the plastic in a raised planter with all the other pine I was growing on in aquatic pots. I then watered the the plant in. It stayed upright for a few years in this position and location. Five years later the plant had grown on and thickened up really well. I had made some big cuts in the interim to reduce the size of the tree and keep the branches more compact. Drainage became a problem though, you can tell by the colour of the needles, much lighter green in appearance. The water was just holding at the top of the pipe and not draining down anymore. Time to see what the roots have done! No chance of removing subtly, out comes the hammer. The roots had surprisingly consumed all of the space, leaving everything very congested at the top. This was fascinating to see. The pine had used every inch available throughout the pipe, all the way to the bottom. The roots were smaller in the more compact area at the top, larger and less fibrous towards the bottom. I never expected to get this much root. Now came the task of removing the old soil as this was no longer required. Back to the chopstick as I find this does the minimum damage to the roots if used carefully. I decided to plant in a deep terracotta pot, these work well really for pines because of how they retain moisture. Large pumice down the bottom for a drainage layer this time. Keeping the tree upwards is a problem again. Wired into position. The roots were quickly beginning to dry out so I didn’t have as much time as I would have liked at this point. This had already been a stressful day for the plant. Too much in one session isn’t a good idea. I was quite pleased with how it was coming on at this point, as this was my first attempt. Closer up on the roots. Filling the pot with a large 50/50 Akadama/Kiryu. Covered the exposed roots in Sphagnum moss and wrapped in cling film. I’ll expose the roots to the air from here bit by bit. Using this method my conclusions are:
Keeping the plant in a very deep pot stimulates extra vigorous growth! Depth is definitely more beneficial than width
Difficult to keep adequate drainage going in order to keep plant healthy. Liquid fertilisers are a must
If I was to attempt this again, I would definitely scale down. I was aiming for Shohin size but the pine grew so rapidly this speedily dropped off the agenda. Using a large downpipe which was difficult to break and therefore tricky to expose the roots gradually which was my plan was probably my downfall. Although I am pleased with the outcome.