Ochna serrulata is an interesting outdoor bonsai for growers in Zones 14-24, or anywhere with winter protection. Its foliage is attractive as the leaves change color with the seasons, its flowers are showy, and its seed formation is unique. This evergreen shrub from South Africa has a slow-growing, spreading habit and a trunk that can develop character traits desired in bonsai cultivation.
Ochna serrulata prefers soil that is slightly acidic and should work well in most bonsai mixes. A balanced fertilizer should be used most of the year, paying attention to iron to maintain the deep green color of the leaves. As winter approaches, switching to a 1-5-5 fertilizer will reduce leaf budding during the cooler months while providing the right balance to maintain root health and prepare for sprout development. flower buds. As with most bonsai that require iron, I like to add a couple of non-galvanized washers or worn nails to the soil mix. Acid soil promotes iron oxidation providing a satisfactory iron chelate for the plant.
Ochna serrulata has long-lasting, fine-toothed oblong leaves that are bronze in color when the plant sprouts with new growth during the spring, which then changes to a rich deep green as the leaves mature. Serrated blades are barbed, but they are soft, pleasing to the eye and easy to handle. The flower buds are kept close to the stem and will develop into bright yellow buttercup-type flowers in early summer. The flowers themselves are very attractive, but the spent flowers are unique. The yellow petals of the flower will abscisse, but the sepals will remain and slowly turn a deep red color. Green fruit seeds will develop from the center of the red sepals, maturing to a vivid, glossy black color. When the fruits have ripened, the appearance of the black fruits against the red sepals closely resembles the eyes, ears, and nose of a mouse. This is why the plant is often referred to as the “Mickey Mouse Plant”, and one of the reasons why young and old love it.
When pruning Ochna serrulata, the shape and structure of the plant should be considered. Pruning is necessary to regulate growth and remove root suckers and trunk shoots emerging from dormant buds. You’ll also want to thin out overly dense miniature canopy branches that can reduce air circulation and light reaching the flower buds. To increase the height of the bonsai, pinch or cut off the growing tips of the side branches. To increase fullness, pinch or cut terminal buds at the ends of branches. The location of the cuts is important. If it is too close to the vegetative bud or flower spur, the bud or spur may die. If it’s too far from the point where you want to induce growth, you’ll be left with a dormant chunk that, lacking metabolic activity, will typically shrivel, dry out, and abscisse, leaving behind dead tissue that can leave an entry point for disease. In most cases, the cut should be about a quarter inch from the bud you want to encourage, and the cut should be made at a forty-five degree angle so that the apex of the cut is above the bud.
I want to emphasize the importance of a sharp tool for all garden pruning, whether it is a pruning shears, scissors or a saw. Nice clean cuts will shut up more quickly and easily than ragged cuts that have torn the bark. If the cuts are clean, active cells in the cambium layer of the stem or branch will grow inward and carefully close the open wound. (In writing this short article on Ochna, I realized that perhaps more complete information on plant pruning in general should be the subject of future articles.
Because Ochna serrulata likes a little shade for best performance, it should make a great bonsai for any non-south facing balcony in Zones 14-24, or anywhere with winter protection. With attractive foliage, showy flowers, and unique seeds, this slow-growing shrub can be trained to develop character traits desired in a bonsai subject.
Copyright: Gilbert Foerster/2010
