Bonsai orange trees are an attention-grabbing addition to any home or garden. When grown properly, bonsai orange trees will bloom and produce edible fruit just like their full-size relatives. Most dwarf varieties of orange will grow from 6 to 10 feet tall, but by combining dwarf citrus growing techniques with bonsai training, growers have been able to keep orange trees even smaller. With just a few basic supplies and some general gardening know-how, anyone can grow and enjoy bonsai orange trees.
Purchase or obtain a suitable species of orange tree that will work well for bonsai training. The most popular orange tree for bonsai training is the Calamondin orange (also known as Chinese, or China orange; Panama orange; golden lime; scarlet lime). This species is naturally compact and has 1 3/4-inch fruit, perfect for bonsai displays. Common dwarf oranges will also work, however the large fruit of these trees tend to look disproportionate to the small trunk and branches.
Provide bonsai orange trees with as much sunlight as possible. In hot, dry climates, place trees where they will receive early morning or late afternoon sun, but protect from intense midday sun. In cooler climates, place trees where they will receive at least six to eight hours of sun each day. Protect bonsai orange trees from frosts.
Plant bonsai orange trees in a fast-draining bonsai potting mix. Purchase a commercial potting mix from a nursery or home store, or create your own mix made of 3 parts peat moss, 3 parts perlite, 1 part small bark and 1 part sand. The peat moss will retain moisture, while the perlite, bark and sand allow the mix to drain well.
Water bonsai orange trees at least once daily from spring through fall, more often during heat spells. Thoroughly moisten the potting mix until water runs out of the drainage holes on the bottom of the pot. Provide slightly less water during the winter (water once every two to three days as needed). Do not let the potting mix dry out completely.
Fertilise bonsai orange trees every other week from spring to fall with a liquid 3-2-1 bonsai fertiliser. Mix the fertiliser solution following the manufacturer's recommendations, and only apply fertiliser solution to pre-moistened soil (never apply to dry soil or it may burn the roots). Withhold fertiliser during the winter when growth slows.
Prune bonsai orange trees lightly while in active growth. Remove suckers that arise from the trunk, but allow upright growth from the branches to grow freely from spring to fall. Trim back upright growth in fall after flowering and fruiting to two leaves. Prune away any thorns that may emerge. Do major pruning when growth slows in winter.