Conker Tree, Horse Chestnut
Introduced to the British Isles in the 17th Century, it is a deciduous Tree, growing to 45m and is priced for its flowers and conkers. It is a hardy but frost tender tree, which flowers in May. It has both Male and Female Flowers on the same tree and can be grown in moist well drained soils in semi-shade (light woodland) or no shade. It tolerates high winds and atmospheric pollution and hence is often planted along city roads. Because of its large leaves and stalks it is best suited to large sized Bonsai.
Informal Upright, Slanting
It like a full sun position.
Water well through out the growing season. It dislikes the pot going dry or getting too water logged, to ensure that pot surface dry out between waterings. Leaf burn occurs easily but does not harm the tree excessively.
Feed biweekly early spring to early summer. Use a low yield Bonsai feed, in the region of N:P:K 5:5:5 or lower. High yield fertilisers will vastly increase leaf-size.
Leaf and Branch Pruning:
As soon as a few small leafs emerge on the shoots, pinch out lead bud. This make the plant concentrate on new growth and helps maintain small leaf size of conkers.
Re-potting & Growing Medium:
Repot young plants every years, every 3-5 years in older plants, in spring. Use a well drained soil, 1 part Akadama and 1 part Pumice.
Conkers are shaped with pruning, as the branches are thick and ungainly. If required you can always use wire in the Autumn just as sap starts descending, but ensure that you use a raffia or protect the bark in some way as it scars easily.