This plant has become a real hit in recent years here in Japan. We have not been too succcessful with it as it is not frost hardy and two plants have already died. But we are trying again this time with a brown boronia not a pink boronia, and with a larger plant. . We grow ours beside our orange tree, a reminder of its requirements since the plant also belongs to the citrus family.
There are approximately 95 speciesof Boronia (Family Rutaceae), all but one of which occurred originally only in Australia. The majority of Boronia species are found in south-western Australia. The Brown Boronia (Boronia megastigma) is intensely fragrant (like Freesia and Osmanthus) and is valued in Australian floral arrangements for its intense aroma. B.megastigma is a small shrub which rarely exceeds a 3 feet (1 meter) in height. It has small leaves which are also aromatic and small cup-shaped flowers. The flowers are about 80-100 mm diameter. Usually, the exterior of the petals is a dark chocolate-brown in colour while the interior is bright yellow. Usually the plant sproduced for both domestic & export are Boronia pinnata or heterophylla which have fairly long stems of vibrant pink flowers and are more attractive than B. megastigma yet still possesses good fragrance and grows taller to 2 m.
POTTING: Boronias will flourish in four parts peat, two parts loam, and two parts coarse sand in a greenhouse that has a minimum winter temperature of 45 degrees. As soon as the flowers die, the shoots should be pruned back by two-thirds. They are then placed in the warmest part of the greenhouse and sprayed frequently to encourage fresh growth. When the new shoots are a half-inch long, the plants should be repotted in flowerpots that are an inch larger than the old pots. Thoroughly firm the compost with a potting stick. Keep them warm and moist for a few weeks until new roots have formed, after which they can be kept in cooler and drier conditions. They can be set outside in the summer. The pots should be placed under ashes to ripen the wood for flower production. Return them to the greenhouse before it frosts. Care must be taken in the watering of this plant because too much water, or too little, can be fatal to your boronia. PROPAGATION: Half-ripe or partly woody shoots that are about 2 inches long, are taken off with a “heel” of the old branch still attached and are inserted into a pot of sand and peat moss in July. Water them well and place them in a propagating case in the greenhouse. When they’ve formed roots, they can be planted into individual, 3-inch pots of sandy peat. Pinch off the tips of the main shoots to encourage bushy growth.