Small gardens, or even small areas within larger gardens, need a tree in scale with the size of the area in which it will sit. But, aside from a handful of species, conventional trees are just too big for these smallest of spaces, and would require yearly pruning to contain its size within the proportion of the space - a job not for the faint of heart, and an expensive one, to boot. So, what are your choices? Well, have you considered upscaling a shrub? Many shrubs are quite suitable and could provide the solution. With just a bit of judicious pruning – a much easier task than cutting a tree – they can offer the benefits of a tree in a size that is more in scale with your area. While frequently pruned trees can looked awkward with missing limbs, shrubs amenable to pruning don’t. The most frequent request is for reasonably fast growing species; as large shrubs and trees are relatively slow growing plant categories, the best you can hope for speed-growth wise is a meter’s growth per year in warm, high rainfall regions; less in cooler, drier areas. Local rainfall, temperature, soils, and aspect will also influence plant growth, so figures given can only be used as guidelines. Where foundations, extensive paving, or unsuitable soils make the digging of a planting hole too difficult, many species on the list grow well in large containers. How to do it:From the outset, soon after planting, trim the shrub from a multi-stemmed to a single-stemmed specimen. Better yet, when buying, look for a specimen already sporting a single stem or without too many lower branches if possible. This will be your starting point; any new stems that start to grow below the main flush of leaves must be cut off. The trees below have non-invasive roots. It is advisable to protect even frost tolerant species for the first couple of year.This fairly extensive list acknowledges the wide variety of growing conditions experienced by gardeners around the country; hopefully, there is sufficient variety to suit most areas. Our list below describes species that usually grow no more than 5 m. - both upscaled shrubs or small trees.
CALPURNEA AUREA - Natal Laburnum
Size: 3 – 4 m; plant in light, dappled or partial shade or sun; moderate drought; evergreen; container; mild frost; Drooping sprays of bright yellow flowers cover this small tree in a good year. The canopy is light and high up so provides only limited shade. Carpenter bees love the flowers. Some gardeners suggest the tree only lasts 5 or so years, but mine is 14 years old and still flowers profusely. Grows in forest, on forest margins and in clearings, on hillsides or the edge of wooded kloofs and in bushveld; Eastern Cape, Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga.
INDIGOFERA JUCUNDA - River Indigo
Size: 2 – 4 m with a 2 – 3 m spread; evergreen; plant in light to partial shade or sun; quick growing; lovely pink flowers in summer; container plant; screen; can plant close to walls and paving; attracts insects and birds and butterfly host plant; moderate frost; easy to prune. Grows in savanna-bushveld and forest, rocky slopes in Eastern Cape, Gauteng, KwaZulu-Natal.
CLAUSENA ARISATA - Horsewood /Perdepis
Size: 4 m; prune lower branches; glossy leaves; lovely small white bell-like flowers spring to summer; plant in shade to partial shade where it flowers better; host plant to several swallowtail butterflies; small berries attract birds; moderate to fast growth; moderate to high rainfall; tolerates moderate frost. Grows in forest, forest edges and woodlands in the Eastern Cape, Free State, KwaZulu-Natal, Limpopo, Mpumalanga, Western Cape.
POLYGALA MYRTIFOLIA - September Bush
Size: 3 – 4 m; plant in light, dappled to partial shade or full sun; container; evergreen; drought tolerant; half-frost hardy; salt, sand, and wind tolerant. Grows in dunes, rocky slopes, in forests, along streams, in scrub and open grassland; Eastern Cape, Gauteng, KwaZulu-Natal, Northern Cape, Western Cape.