Cordyline is a small genus of around 20 species with about 8 found in Australia. The genus is sometimes placed in the family Asteliaceae and is very familiar to many gardeners through Cordyline australis, a native of New Zealand but commonly available in the general nursery trade in Australia.
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The genus is characterised by plants with long, strap-like leaves arising from thin trunks. Some of the exotic species are cultivated for their colourful foliage.
Cordyline stricta is a tall, narrow plant to about 2-5 metres tall. The leaves are deep, glossy green, linear in shape and up to half a metre long by about 25 mm wide with a sheathing base.
The small, white to purple flowers occur in winter and spring in clusters (panicles) from the upper leaf axils. They are followed by black berries.
This is the most commonly cultivated of the Australian species and has proven to be adaptable in a range of climates although it is a little frost tender and may be damaged in colder areas. The plant usually recovers from damage, however. It prefers moist soils in semi shade but is surprisingly tolerant of extended dry conditions once established. When small, it makes an excellent container plant and can be kept indoors for long periods.
The cultivar ‘Rubra’ has attractive reddish foliage. Propagation can be carried out from seed which germinates readily. Division of larger plants is also a useful method of propagation and stem cuttings also strike readily.
Pandoorea jasminoides is a small genus of 6 species, 3 of which occur in Australia. P. jasminoides is well established in cultivation and several cultivars are known. It is a vigorous twining plant with pinnate leaves having between five and seven lance-shaped leaflets up to 50mm long.
The large flowers are tubular, ending in five spreading lobes. The flowers are usually pale pink with a deep pink throat and are about 35 mm long.
Flowering occurs over a long period between spring and late summer. The flowers are followed by large elliptical fruits which split to reveal elongated, winged seeds. This is a popular plant in cultivation. It is very hardy in topical to temperate regions although it may be damaged by frost during very cold winters. It is adaptable to any reasonably drained soils and will grow in full sun to partial shade. It is ideally suited to growing on a fence or trellis. It prefers a reliable water supply but, once established, will tolerate extended dry periods. Propagation can be carried out easily from either seed or cuttings.
ZUCCHINI TIPS
Home gardeners growing zucchini plants sometimes comment that the fruits begin to form and then drop off the plant. This is most probably due to lack of pollination.
Even though there may be bees around the garden, the flowers on zucchini plants are rather large and effective pollination may not occur. However, it is possible to hand-pollinate the flowers, thus almost guaranteeing that fruit will set and fresh zucchinis will be available.
Hand-pollination is a relatively easy task to undertake, once the individual male and female flowers have been identified.
Male and female flowers grow on the same plant. The female flowers will have an immature zucchini at the base of the petals, while this is absent in male flowers. Initial flowering on a plant will have male flowers, but female flowers will soon be produced. The task is to place some of the pollen from the male flower onto the female flower. This can be done by either to two methods.
A small paintbrush can be brushed over the male flower and the yellow pollen particles will adhere to the bristles. These can then be transferred to the female flower.
A second method involves removing the male flower from the stem and placing it into the female flower, placing the flower in an upside-down position.
If pollination has been successful, then a young zucchini will soon form at the base of the female flower. The fruits should be removed while they are still small, soon after the flower withers on the end of the fruit. Regular picking will assist in maximising fruit production. They young fruits will also have more flavour.
TREE DAHLIAS
Tree dahlia plants are now full of healthy, strong growth. They still have quite a considerable amount of growth, particularly in height, to add to the plant. However, the thick bamboo-like stems are quite brittle and damage easily in stormy winds.
Reduction of plant height by about half at this stage of their growth will encourage lateral, side shoots to be produced. These shoots will be thicker and more abundant, resulting in more flowers and less likelihood of damage from strong winds.
Supporting the trunks is also advisable now, before they become too heavy to be easily managed. The use of a softer, more pliable material, such as stockings, rather than thicker string or rope materials, will avoid the stems being cut and damaged. Supporting the stem at several height levels will also be more effective.
Tree dahlias generally produce clusters of single lavender-coloured flowers with yellow centres. Single and double white flowering varieties are sometimes available.