Five Species That Make Great Indoor Bonsai
Most bonsai species, even if sold as "indoor bonsai" are actually meant to live outside. They need direct sunlight. They benefit from temperature changes, both daily and seasonally. Unlike other house plants, they require frequent watering, and occasional root and foliage pruning. In short, they require all of the same care and needs of outdoor bonsai, but they can tolerate indoor conditions. This makes them the perfect choice for someone who wants to decorate a home or office with a beautiful bonsai tree.
Interior lights are usually insufficient to supply the indoor bonsai with enough light to photosynthesize, so it is important to place the tree in an area that gets direct or indirect sunlight through a window. However, you need to be careful to expose the tree neither to the freezing cold of a windowsill during the frozen winter, nor the sauna-like heat of an unventilated windowsill area in the summer. Fluorescent lighting or high-intensity growing lamps can substitute for sunlight for some species.
Ficus is one of the most popular indoor bonsai species. There are two that are very good for indoor growers, and are easy enough to maintain that they make good beginner trees.
Ficus benjamina is a weeping fig that is evergreen, fast growing, with lush foliage and interesting roots. It can best be shaped as a formal or informal upright, or in a weeping banyan tree style. They scar easily and don't easily heal over large pruning wounds, so it is best to grow these up from smaller trees than to do trunk chops from larger trees.
Ficus neriifolia is a willow-leafed fig that is known for its thin foliage, strong root spread and twiggy branch ramification.
2. DWARF UMBRELLA TREE
The dwarf umbrella tree, or schefflera arboricola, is a hardy and popular evergreen houseplant that looks great in a bonsai pot and can be trained as a bonsai in a variety of styles, including weeping banyan style or with exposed roots over rocks. It is evergreen and produces palmately compound sets of 7 to 9 leaflets. During periods of strong foliage growth, high humidity and root street (from pruning, or becoming root-bound), this species may produce highly prized aerial roots that will reach down into the soil from branches above.
Scheffleras will also bud back on old wood, allowing for heaving pruning if necessary to develop the desired shape. They do not, however, develop extremely woody trunks, which causes some bonsai collectors to avoid them. They do not respond well to wiring and bending, and directional pruning and cutting back to a younger apex are the primary ways of shaping and training them.
They will tolerate low indoor lighting better than most bonsai species, and they are tolerant of low humidity better than most, too. They should be repotted every other year. If healthy, they will tolerate defoliation once a year.
3. CHINESE ELM
Chinese elms (ulmus parvifolia) are not only great trees to grow indoors, they are among the easiest trees for bonsai beginners. It's fast growth, small leaves, woody trunks and short nodes make it very easy for a beginner to grow a healthy and attractive bonsai tree, even inside a home or office.
They are more tolerant of underwatering and overwatering than most bonsai species. They respond well to wire, or can be trained by directional pruning. They can grow in good or bad soil, as long as you don't let them simply sit in water, or dry out completely. They are easy to grow from clippings, or, if you have mature Chinese Elms in your neighborhood, they sprout prolifically from fresh seeds.
And, believe it or not, they are edible. The seeds are edible, if bland, and the fresh light green leaves taste like lettuce and can be mixed in with a salad for an extra layer of flavor. Bon appetit!
4. SNOW ROSE
The snow rose, or serissa japonica, is a tree with a woody stem that produces tiny leaves and very small, attractive and plentiful flowers. It is evergreen or semi-evergreen, and will do as well inside as it does outdoors. It can flower in every season, but it is most prolific from early spring to late autumn. Flowers are usually white, but pinkish cultivars are available, as are variegated cultivars. They develop twiggy branches that can be easily ramified by pruning back to one or two sets of leaves when branches get leggy. They are sensitive to changes in light, temperature and watering, and may lose some foliage, temporarily, when they are stressed by such changes, but they are usually quick to rebound to health.
5. FUKIEN TEA
The fukien tea tree, (carmona retusa), named for the province of Southern China where it is native, can grow to more than a dozen feet if planted in the ground outside, but it also thrives indoors, and it is one of the most popular mass-produced indoor bonsai species offered for sale by roadside vendors, fair vendors and big box retailers. It produces small white flowers, year round, and small red fruits. The foliage is small, rich green, and waxy. This tree is well suited for an informal upright style. Unfortunately, many of the mass produced fukien tea trees are styled into a very curvy S-shape that is difficult to alter once the trunk becomes too thick to bend with wire.
It does best in stronger light, for at least 5 to 6 hours per day, and although it will thrive indoors, it benefits from spending some time outside in spring and summer. It does not do well if temperatures drop below 40 degrees. During winter months, especially in colder climates in which cold outside air comes in from outside and is heated, caused very low humidity, this species will benefit from the use of a humidity tray.
Repot every other year, or whenever the roots begin to fill the pot (i.e., you see root masses pushing out the bottom of your drainage holes) and prune off the bottom quarter of the root ball. As a tropical species, this tree prefers repotting to take place in the middle of summer, rather than late winter or early spring like many other species. Keep new growth pruned back when it gets too long and unkempt, but do not remove all of the growing tips. Fertilize regularly throughout the growing season.
Indoor Bonsai Care
Maintenance of an indoor bonsai tree is not much different than maintenance of outdoor species. Never permit the soil to become completely dry. If your tree is placed in a hot area of the house, more frequent watering, or the use of a humidity tree may be necessary. A humidity tray is a shallow tray filled water and small stones, on top of which you place your tree's pot. The evaporating water provides moisture to the tree, via absorption through the foliage. Fertilizer should be applied, at half strength, at least monthly, except during the winter season. Like any bonsai, you should remove new growth that is unwanted, by clipping or pinching off. At least once a year, you should inspect the soil to make sure the tree is not root-bound. Most indoor bonsai species benefit from repotting every other year.
With proper care, feeding and watering, your indoor bonsai can remain small, healthy and attractive indefinitely.