The wisteria is a hardy, woody vine of the Pea family. This climbing tree produces an irregular canopy of glossy foliage complemented by its fragrant and colourful blooms. Its vigorous growth, along with its tolerance to shade and pruning, make the wisteria a good selection for bonsai. The brilliant colours of the Chinese and Japanese wisterias make these wisteria species common bonsai selections.
Place the wisteria on a clean, flat surface and inspect it carefully. Remove any dead or ailing branches and stems with sharp, sterile pruning shears. Cut back branches for shape. Thin out heavily foliated areas to promote healthy cell development.
Remove the wisteria from its original container and gently crumble the soil from around the root system. Inspect the roots carefully and trim any dead or wilted roots back to the root mass.
Choose a well-drained potting container for the wisteria. Select a container with a depth that is slightly larger than its root mass and a width that is at least 2/3 the width of its canopy. Pick a container with several drainage holes, as opposed to just one, to ensure an even, well-drained soil environment.
Line the bottom of the wisteria's potting container about 1/3 of the way with soil. Place the wisteria in the centre of the pot and fill it the rest of the way with soil. Irrigate the newly potted wisteria bonsai immediately after repotting. Pour tepid water evenly, at soil level, around the base of the wisteria until the water runs evenly from the drainage holes.
Place the wisteria bonsai in a warm, sunny location that receives at least six to eight hours of full to partially shaded sunlight each day. Elect outdoor locations over indoor locations whenever possible, as the wisteria's development benefits from the unlimited air circulation.
Irrigate your wisteria deeply and regularly to maintain a moist, but not saturated, soil environment. Water this bonsai just before its soil begins to lose moisture. Increase the irrigation schedule during the hot, dry summer months.
Feed this rapidly growing wisteria bonsai in the early spring, just before the tree blooms. Cease all fertiliser applications while blooms are present. Resume the fertilising applications after the flowers have dropped until mid to late fall. Select a low-nitrogen fertiliser especially designed for wisteria, and apply according to the package's instructions.
Be patient with your wisteria bonsai. Allow it time to grow without being picked at or fiddled with. Thin out the interior foliage periodically throughout the growing season to increase light penetration and air circulation throughout the wisteria. Make cuts for shape in the late fall and early spring each year, after removing dead and damaged areas.
Repot the young wisteria bonsai every other year in the early spring. Use a nutrient-rich, well-draining potting soil, and repot the wisteria just as you did with the initial potting. Always clean the potting container with soap and warm water before using it to repot. Use only fresh soil; never reuse the soil.