Tsuga is a genus of 10 species of evergreen, monoceious, coniferous trees found in forest from the Himalayas to north Burma, west Vietnam, China, Taiwan and Japan, it is also found in North America. Tsuga species feature flattened, usually linear leaves (similar to that of Yews), with silvery white bands beneath.
Tsugas are typically tall, graceful trees with spreading branches that droop downwards at the tips creating a cascading effect. The bark is a cinnamon red colour and it becomes deeply furrowed with age. Cones are small and pale brown when mature; after dropping their seed they remain on the tree for a quite a long time.
Species suitable for bonsai include;
TSUGA CANADENSIS/ Eastern or Canadian Hemlock
A broadly conical tree to 25 metres tall in its native eastern North America. T. canadensis has linear finely-toothed, mid-green leaves to 2cm that taper from their bases and are 2-ranked. There are many varieties of Tsuga canadensis available including dwarf and prostrate forms. Frequently seen is Tsuga canadensis ‘Jedoloh’ which has a common name of ‘Birds Nest Tree because of its habit of spreading and forming a depression in the crown that resembles a birds nest.
TSUGA HETEROPHYLLA/ Western Hemlock
Narrowly conical tree with narrowly-oblong, finely-toothed, glossy dark-green leaves 0.5-2cm long which are 2-ranked. Native to west North America (Alaska to California) where it can reach heights of 20-40metres. (Extremely shade tolerant but requires extra shelter from the wind).
TSUGA DIVERSIFOLIA /Japanese Hemlock
Broadly conical, later domed tree, orange bark and orange shoots with short, fine hairs. Linear leaves are very glossy, dark-green, 0.5-2cm long and 2-ranked. Native to north Japan where it can reach heights of 15metres.
BONSAI CULTIVATION NOTES
POSITION: Partial shade, particularly in Summer. Tsuga need protection from strong, freezing winds that will quickly dry out the foliage.
FEEDING: Every two weeks throughout the growing season.
REPOTTING: Every two years in Spring as new growth starts, or late Summer from mid-August to October, use a basic soil mix. Older established specimens can be left 5-10 years between repotting.
PRUNING: Hemlocks grow very slowly and as new growth is similar in colour to mature foliage (except Tsuga heterophylla) growth extension can grow unnoticed and trees can easily get out of shape. Prune hard in late-Winter any trees that have grown out of shape. Wiring can be done at any time of the year though care should be taken not to damage tender new growth in Spring. Cut back fresh growth as it extends to produce a more compact second flush of growth and back budding from the base of old needles.
Take care when wiring as Hemlock have a habit of marking easily.
PROPAGATION: Sow seed outside in Spring. Root semi-ripe cuttings in late Summer or early Autumn.
PESTS AND DISEASES: Largely trouble free.
STYLING: Suitable for all forms except Broom, in all sizes.