GROWING PLANTS:

22JUNE2011:
HOW TO GROW:

	Growing Acacia galpinii

Monkey-thorn is easy to propagate from seed that is not parasitized. Like other plants belonging to the Fabaceae, seed of this tree must be soaked in hot water overnight and then sown the next day. Seed must be sown in a seedling tray filled with river sand. To avoid unnecessary moisture loss, the seed can be covered with vermiculite. Seedlings are fairly fast-growing but must be protected from frost probably for the first growing season. Although it is frost-tolerant, severe frost often kills off tender young branches. The tree prefers full sun. Do not plant it too close to buildings as it has extensive roots.

Growing Faidherbia albida

Faidherbia is one of the acacias. Its seeds need to be treated with boiling water before sowing. The seeds can be immersed in hot water overnight. Select swollen seeds, they are the ones that are viable (are able to germinate) and sow them in river sand. Seeds must not be buried deep, but must be covered with a layer of sand the same size as the seeds.

The seeds usually germinate after two to five days. The seedling develops a long taproot and must be transplanted directly into the garden. The correct time to transplant the seedlings is when they have reached a height of 50 mm. Caution must be taken to protect young plants from frost.

Young trees are mostly attacked by white Australian bug. They can be treated with systemic (absorbed by the plant system) insecticides.

Growing Acacia erioloba

Acacia erioloba can be propagated easily by seeds. The seeds generally need some treatment to weaken the protective waterproof seed coat. They can be put into boiling water and then left to soak for a couple of days until the seed swells. Alternatively the glossy coating can be lightly sanded before soaking. Seeds may then be sown in a well-composted, sandy seedling mixture, and kept in a warm and moist positon. Seeds usually take four to six weeks to germinate. It is also possible to propagate it with semi-hardwood cuttings, but this is not a commonly used method. Trees start to flower when about 10 years old.

Growing Acacia caffra

The trunk is very often crooked which gives the tree wonderful character in a garden. It is frost and drought resistant and has a growth rate of about 700mm - 900mm per year. Like other Acacia species the common hook-thorn throws a light shade which allows enough light through to enable lawn to grow beneath. Acacia caffra has a stately shape and looks very elegant in a sweep of lawn. It responds well to pruning. Avoid planting near paving or buildings as it reportedly has an aggressive root system.

It grows easily from seed. The seeds need hot water treatment before they will germinate. Simply pour hot water over them and allow to cool. You will see if this has worked as the seeds will begin to swell as they absorb water. Do not leave them in the water for longer than 24 hours or they will start to deteriorate. It is best to sow directly into black bags as the taproot is long and is sensitive to transplanting.

Growing Barleria obtusa

Barleria obtusa grows very well in full sun and semi- shaded conditions. Although B. obtusa is a summer rainfall subject and can grow in a wide range of soils, it thrives in the winter rainfall, W. Cape area but requires well drained soil conditions. Lots of compost added to the soil will give plants a good boost.

The bush violet also shows good drought resistant properties, however, for excellent growth, regular watering is encouraged.

The shrublet can be planted in mixed borders and banks. Regular pruning is necessary after the shrub has flowered, for neat and compact growth. To encourage more flowers, nip off the shoots during spring and early summer.

B. obtusa is easily propagated from seeds, cuttings and layering. The seeds must be collected before the seeds are dispersed, when the seed capsules turn brown in colour. The flat seeds are sown in seed trays in a well- drained medium. Cover the seeds with sifted soil or sand. Keep trays in a shaded area.

Semi-soft wood cuttings can be taken during the summer from new growth. Dip the base of tip or stem cuttings into Serradix No. 2 hormone powder to stimulate fast root development. Successful results can be expected in four weeks.

Layering is also an easy method of multiplying this plant. Choose a long branch which has not flowered. In autumn prepare the soil, by filling a small hole with coarse sand. Bend the branch and remove the leaves of the area that touches the soil. Score the underside of the naked stem to injure the tissue. Peg the bent branch into the hole and cover it with soil and coarse sand. Stake the tip and keep the spot moist until rooted.

In habitat B. obtusa is variable with different forms. White and pink flowered forms have been introduced into cultivation. Barleria 'Purple Prince' has a spreading habit with darker violet flowers and has slightly glossy leaves. This cultivar is very popular and a garden asset for difficult areas.

Barleria is a large genus composed of 120 species mostly confined to Africa and in tropical Asia. There are about 50 species found in South Africa. In the recent past new species have been discovered, such as B. greenii from Natal. This genus bears investigation as several other Barleria species also exhibit horticultural potential.