Over many years, plants have that have variegated foliage have become available. The foliage on these plants generally develops their attractive leaf patterning through cell mutations.
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Although the majority of leaf variegation contains yellow, cream and white combinations, there are also many specimens available that display combinations of pink, red and cream colourings.
Sometimes a plant in the garden will “throw a sport”, that is, a shoot that has foliage that is different from the main plant. Through careful propagation, these shoots can be used as cuttings to develop new plants with attractive leaf colouring. However, it can take many years to ensure that future plants bred from the variegated material will continue to produce the variegated foliage.
Camellias, particularly, can sometimes produce a variegated sport. Because the variegation in the leaves is a mutation, the plant will often try to revert to the all-green foliage because the mutation isn’t very stable.
Therefore, it is important for gardeners and horticulturists to regularly check the foliage on plants with variegated foliage in order to ensure that parts of the plant are not reverting to the original leaf form. If a branch or stem that has plain green foliage is found, it is important to remove it, cutting it back cleanly against the main trunk.
The plain green foliage will be more vigorous than the variegated foliage and can quite quickly overtake the variegated plant. While some gardeners may find the contrast in foliage attractive and interesting, failure to remove the parent or species branches will eventually lead to them dominating the less vigorous cultivated branches. Continual monitoring of the plant should then be carried out.
Reversal of leaf colouring applies not only to shrubs, where the change in foliage may be more noticeable, but also to trees with variegated foliage.
Maples, such as the Acer negundo varieties, often used as street and specimen trees, can be subject to leaf colour reversal. There is, however, another form of variegation that does not result from a benign mutation of plant cells. This form of variegation is the result of disease-causing viruses.
Roses would be one of the more common plants affected by this problem, with leaves developing a yellow, mottled appearance. It is generally considered that this disease is spread by aphids, which enjoy the sap of young, new growth.
Black spot, however, will also produce discolouration on the leaves of roses, forming a brown spot with a yellow surround.
Fruit trees, in particular apples, can also be affected by the apple mosaic virus. Prevention is the only form of control as, once a plant is affected by a virus, the virus remains in the plant’s system.
Sterilising cutting and pruning equipment will assist in preventing the spread of viruses. Weeds can harbour viruses, so keeping the garden weed-free is another preventative method.
HEALTHY PROTEAS
Proteas are often admired in floral arrangements and are purchased for their ability to last several weeks in a vase. Because they are related horticulturally to a large group of Australian native plants, including banksias, grevilleas and waratahs, they require similar growing conditions.
They have a low tolerance for artificial fertilizers. Applications of superphosphate will kill proteas. However, they require magnesium and this can be applied as Epsom salts, scattered over the root areas and then watered in well. Spring is an ideal time in which to do this.
Proteas produce a range of flower styles and colours, on plants that vary from quite small through to large shrubs. Flower colours are predominately shades of pink, although whites, creams and yellows are also available. Flowers are produced from May through to mid-September.
An application of mulch will benefit plants, although mushroom compost should be avoided as it contains fertilizers high in phosphorous. It is important to keep the mulch away from the stem as proteas are susceptible to infections such as collar rot, if the lower stems are buried in moist mulch. Mulching will help to avoid the production of weeds below the plant, as proteas resent having their roots disturbed.
Pruning a protea enables the gardener to shape the plant, and this can initially be done through the cutting of flowers for indoor use. Tip pruning in spring and summer will help establish a good shape in a young plant.
More mature specimens should be pruned immediately after flowering, leaving about 10cm of healthy stem.
This will encourage the plant to produce shoots from above the cut and these will produce flowers in the following season. Leucadendrons and leucospermums should also be pruned in the same manner.
A selection of proteas might include: “Pink Ice”, King protea and Pink mink, all growing to 2 metres, Peach protea and Queen protea, growing about 1.5 metres and Honey protea, which grows to 2.4 metres in height.
CONSIDER PARSLEY
Parsley plants (Italian or Curled varieties) can be one of the more useful plants to have in a garden. They look attractive in a vegetable or herb garden, but can also have a visual impact when planted into a flower bed or between lower growing shrubs.
Young plants are available in pots or seedling trays, but plants can also be grown from seed. However, parsley plants can be difficult to raises from seedlings.
