Geoff Hicks | Keeping rust off your geraniums

Although geraniums are often classed as plants that take plenty of sun, flowering seems to be better if they are growing in a position of part sun.

Geraniums are affected by few pests and diseases. However, one of them is prevalent just now. Rust, a fungal disease, causes yellow-orange raised spots, initially on the underside of the leaves. The spots are caused by spores that develop on the leaves.

As the disease progresses, the tops of the leaves display yellow spots, spoiling the look of the leaves. If affected leaves are left on the plant, they eventually become quite disfigured and eventually fall from the plant.

Prevention is the best treatment, providing a sunny position with good air movement. Rust develops when the leaves are moist. Therefore, watering the plants in the morning, so the leaves have time to dry, is a good strategy for trying to avoid the development of rust.

If rust-affected leaves do appear, they should be removed from the plant by breaking them at the main stem. In this way, the leaves come off cleanly, without damaging the stem.

The affected leaves should be disposed of in the general rubbish, rather than being placed in the compost where the rust spores can affect more plants.

Garden hedges, such as those that have been made from plants such as lily-pillies, camellias, westringias or golden durantas should now be shaped or pruned as they rapidly produce their new spring growth.

This will encourage increased numbers of new shoots, with a resultant thick, rich appearance. Older, thicker branches can be removed, while retaining stronger, more supple growth to maintain the desired growth and shape.

A variety of tools can be used, including trimming the plants with hedge-cutters, either electric of manual, and cutting individual stems with a pair of secateurs. The material that has been removed will generally be too soft for use as cutting material at this stage of its growth.

An application of Seasol will encourage new growth by feeding the root system.

Cymbidium orchids that have multiplied and now fill their pot will have reduced flowering as they will gradually become starved of needed nutrients.

Once the plants have been removed from their pot, which may take some effort if they are very overgrown, the old “soil” should be removed from the roots.

Then the plant should be divided into smaller plants, making sure each one has some older shoots as well as one or two strong new shoots that will eventually produce the flower spikes.

Older and damaged roots should be cut from the plant. It is advisable to sterilize the secateurs in between treating plants in an effort to avoid the transfer of diseases.

Perhaps the most important thing to remember when repotting orchids is the medium that is placed into the pot

with the plant. Orchids require a very free-draining mixture as their root system will quickly rot if it has been placed into heavy soil. A mixture of small to medium sized pine bark is good to use. This will allow the water to flow though as well as letting the roots breathe.

Cymbidium orchids should be fed with Campbell Orchid Special Fertiliser (blue form) from now until December. Then the yellow form should be applied.

The fertiliser should be made into a solution using 15g in 5 litres of water and applied, particularly to the leaves, about every two weeks. It is important to allow the fertiliser to drain through, and away from, the pot. If the pot is allowed to sit in a saucer or similar container containing excess fluid, there will be a build-up of salts around the base of the pot.  This will be evidenced by a layer of white material around the base. An excess of salts will eventually be detrimental to the health of the plant.

The Native Frangipani originates from rainforest areas between Sydney and the Tablelands areas of Cape York.

It is an open and upright growing tree that reaches 20 metres when it is growing in rainforest areas, where it has to compete with other trees for light. However, when growing in suburban gardens and parks, the trees generally only reach eight metres.

Native Frangipani trees display their five petalled flowers that are up to 50cm across, for about six weeks, during spring. The flowers open as a cream colour, then darken to a yellow as they age, giving the tree a multi-coloured effect.

The flowers are produced in clusters and have a pleasant fragrance that might be considered to be similar to that of exotic frangipanis.

The leaves are evergreen and display a shiny dark green upper surface with a paler green underside. Positions of full sun to part shade are suitable for Native frangipanis.

Regular pruning from planting can be used to encourage the development of dense foliage as well as masses of flowers. Planting the tree in an area adjacent to buildings will allow the fragrance to be enjoyed on the evening breezes.

Trees are fast growing and frost resistant.  Dwarf forms of the Native frangipani are sometimes available.

geoffh.gardening@gmail.com

Maitland and District Garden Club