Where the need is simply to fill a large space with greenery, there are a good collection of indoor shrubby plants available, generally at quite reasonable cost. They in fact fulfill much the same purpose as hardy shrubs for the garden. They are durable, and have leaves of interesting shapes, colors and textures. They form useful bulky shapes as whole plants, and can generally be kept pruned or clipped to a reasonable sue or be allowed to grow to large dimensions.
They are, in fact, good general-purpose houseplants that are much used by commercial horticulturalists for displays and decorations of various kinds. Such plants as Fatsia japonica, Grevillea robusta and the Pittosporums are particularly useful as 'working plants'. They will look good and withstand wide ranges of temperature - from the draughty entrance of a hotel to the hot and stuffy atmosphere of an overheated room or a cold and miserable marquee. If the grower who depends on his plants for a living can rely on them, so clearly can the amateur at home.
Two graceful shrubs that can be grown from seed with little difficulty in warm conditions are Dizygotheca elegantis-sima (commonly called the false aralia) and Grevillea robusta (the silk oak of Australia). Both have delicate, feathery leaves that are rather like those of some ferns (although the false aralia's are dark reddish-brown).
Both will develop into plants of considerable size if their growing tips are not removed at an early stage in order to check upward growth. The false aralia will, in fact, take on tree proportions. Unfortunately, as it does so the leaves become much coarser and the appearance is generally far from elegant Shaded, moist draught-free conditions will suit it best with the temperature maintained at around 20°C (68°F).
The silk oak, on the other hand, will fare very much better if the conditions are cool and light and no harm will be done if the plant spends the summer season out of doors. To get the best out of these plants it is essential that the root system at no time becomes excessively dry. (But beware of overwatering, too.) Regular feeding of established plants is also a must and annual potting on in the spring is advisable.
When shopping for indoor plants, there is no need to restrict yourself completely to plants suitable purely as houseplants. You can sometimes select kinds that may be planted out in the garden when they have lost their attraction indoors. Eriobotrya japonica (loquat) and Euonymus japonicus are two such plants. Both require cool, light conditions when used as potted plants. Outdoors the loquat will need the protection of a sheltered wall in colder areas. Not many house plant growers sell these, but they are usually obtainable from shrub nurseries and garden centers.
There are several varieties of Euonymus with variegated leaves from one to three inches long. The Eriobotrya has much larger leaves - up to 12 inches long - that are a beautiful grey when young.
Equally at home in cool indoor positions and also outdoors where winter conditions are not too harsh are the false castor oil plant Fatsia japonica (sometimes sold as Aralia sieboldii) and a hybrid derived from it Fatshedra lizei. Like the true castor oil plant (Ricinus communis), F. japonica has large, dark green palmate leaves with seven to nine pointed lobes. It is one of the most useful of all indoor plants. Exceptional plants may reach a height of some eight to ten feet in as many years, but they usually remain much more compact. They like cool conditions - around 13°C (55°F) -and annual potting on when small. But once plants are in 10-inch pots, they can be sustained for several years by regular feeding during the growing season.
The variegated form of F. japonica, with whitish patches on the leaves, is a particularly fine plant But it is more difficult to obtain and more expensive than its plain relative. It also needs a slightly higher temperature and more.
careful watering if browning of the leaf edges is to be avoided.
F. lizei is a man-made hybrid between an ivy (Hedera) and F. japonica - hence the name Fatshedra. Hence, too, its leaf shape and habit. It has leaves similar in shape to those of F. japonica but about half the size. It tends to grow tall, and can be trained up pillars or staircase handrails. Or it can be kept more compact by regularly removing the growing tips. This plant also has a variegated form, but it is much more difficult to keep in good order. Both types are liable to be damaged by leaf-cleaning agents.