In bonsai, a raft is one trunk along the ground supporting a number of ‘branches’ that have become trunks in their own right. Rafts come in straight and sinuous and are usually developed when a stock plant has branches on one side only.
Plants that are good for rafts are privets, figs, crabapples and junipers, to name a few. The trunk is scored along the side with no branches. Cuts can be made into the trunk, cutting through the cambium and placing a small pebble to force the slit to stay open. Another method is to scrape the bark exposing the cambium in a number of areas. The trunk is then planted in a training pot (a styrofoam box is ideal) and the actual root ball is slightly buried and the mound on top of the soil is covered with soil and spaghnum moss and always kept moist until the new roots develop. Hairpins, made from bonsai wire that are bent into U’s, are placed along the trunk to keep it in close contact with the soil. The tree can also be tied down. It is vital that the exposed cambium areas are kept in contact with the soil and kept moist.
Once the plant has started developing roots and shooting, a normal fertilising regime can be started. When the growth is strong enough the new ‘trunks’ can be wired into shape and position. With privets and figs, it is not necessary to have roots. A branch can be started by nicking as above, burying part way in the soil and keeping the plant moist. It is also okay to have a ‘bridge’ raft where there are roots at each end and the branch bows above the soil level.
Every year at repotting the original rootball is gradually shaved back until it is level with the ground. Do crabapples when they are dormant, figs in October/ November and junipers and privets in spring. Try other species as well.
Developing a raft can take several years but the raft bonsai can be a very interesting style and provides a good learning curve as well as utilising what could be a poor specimen for an upright bonsai.
A bridging raft, a straight raft or a sinuous raft, try something new… go for it. The variations are endless and exciting.