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September Gardening – Sue McDougall

September is when the gardening world goes mad. There is no excuse to avoid the garden as the weather is warm and the days are sunny. Spectacular displays of colour are in every garden and the vegies are growing right before our eyes.

Lawns that are looking slightly yellow at this time of the year will benefit from a quality slow release lawn fertiliser applied to them.  Controlled release fertilisers reduce leaching as they release their nutrients gradually so it’s always best to select controlled release fertilisers over quick release types. Better Pets and Gardens stores have a wide range of the best on the market.

African lawn beetle will be getting the blame for dead patches in the lawn as the weather warms up but usually these pests are not the culprit. The soil can become water repellent and will not soak into the root zone but bead and run away, the major cause of dead patches in lawns. A wetting agent is a must as it allows the water to soak into the plant’s roots where it is needed. As the weather warms up treat the whole garden, not just the lawn. There have been many advances in wetting agent technology in recent years as this problem not only affects home gardeners but also broad acre farmers, commercial growers and golf course curators. Quality products now available will help sort out non-wetting soil problems and the garden will be a lot healthier for it.

Citrus trees require an application of fertiliser as they are starting to flower and will be setting fruit soon for next year. Look for silvering and curling on the new foliage which will indicate an infestation of citrus leaf miner, common at this time of the year. An application of pest oil is very effective at controlling these pests.

In frost free areas, warm season vegetables can be planted including beans, beetroot, capsicum, carrot, chilli, Chinese cabbage, cucumber, eggplant, honeydew melon, repeat harvest lettuce, pumpkin, rock melon, silverbeet, squash, sweet corn, tomatoes and zucchini. Growing vegies from seed is the cheapest way to establish a vegie garden.

September is the best time for planting flowering annuals that will give continual summer colour. Petunias, portulacas and vincas are the best pick for waterwise seedlings as they will thrive on almost no attention so you can imagine what they will look like if they have had fertiliser and good soil improver added to the soil when they are planted. Fortnightly applications of liquid fertiliser over the foliage will keep seedlings looking fantastic throughout the growing season.

Feed the spring flowering bulbs after they have finished flowering with a complete bulb fertiliser. After flowering these plants tend to be forgotten but they are busy developing the embryo for next year’s flowering before they go dormant. Sprinkle the fertiliser around the surface of the soil and water it in well. Reapply in four weeks.

After flowering, the lavenders will also benefit from a trim in late spring as grey foliage plants tend to become woody and require regeneration. Some grey foliage plants tend to drop dead if trimmed back hard so are best when pruned in several stages. The secret is to select about one-third of the main branches and trim them back hard. Let them shoot away and after a few weeks trim back the next lot of branches, then follow with the last lot of branches in the same process. This will allow the plant to recover over a period of time.

Trim wax flowers after they have finished flowering. Better still, trim them while they are flowering and bring inside to enjoy as a cut flower. This way you have the best of both worlds; a lovely vase display and a trimmed shrub.


Written by Sue McDougall, a qualified horticulturalist and experienced garden centre owner who grew up in the WA wheatbelt and has had experience in gardening throughout the entire state.  You may know Sue as the garden expert on 6PR radio and by her many TV appearances.

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