I have some plants that always seem to have insects attacking them. Why?
‘Gardening is the art of killing weeds and bugs to grow flowers and crops for animals and birds to eat’ (according to ‘A Dictionary for Weedpullers, Slugcrushers and Backyard Botanists’ by Henry Beard and Roy McKie).
At times it would seem that much of a gardener’s time is spent solving problems in the garden and not actually enjoying the garden itself.
I have found that many if not most insect problems of Australian plants in the Riverland is directly related to ‘soft’ growth promoted by frequent light watering. This type of watering is relative. By this I mean that frequent light watering to a lettuce in mid summer might be a short sprinkle four times daily where as it may mean fortnightly watering to a local mallee Eucalypt.
The soft growth produced from very frequent light watering is also relative to the plant species. To take our example again, the lettuce with soft growth will wilt very easily and the leaves of the local mallee Eucalypt will be ‘soft’ to touch compared to the same species growing on natural rainfall in the Riverland.
I am quite convinced that it is this soft growth particularly in spring and autumn that attracts insects looking for sites to lay eggs that will provide good feeding sites for their emerging young.
The most straight forward way to keep the insects moving on to easier feeding sites is to provide tough plants that are watered deeply (species specific watering regime).
This is the ‘NIMBY’ technique. That is ‘not in my back yard’. When the plants are tougher than elsewhere, insects will also go elsewhere.
The best way to achieve this in practical terms is to group plants of similar watering requirements together and water (if required) appropriately. Shallow rooted plants that require fairly frequent watering such as ferns; lawns, annuals, vegetables and roses should be reasonably close together.
Then perennials, many bulbs, herbs and plants from rainfall zones with an annual average of around 1000mm should go together. This group would also include many Australian native plants. This group in mid summer would need something like fortnightly watering.
Many plants from the Mediterranean, most cacti and succulents and Australian plants from rainfall zones of around 500mm per year should be grouped together. This group would need about monthly watering in summer. Often four or five waters for the entire year would be sufficient for healthy growth.
Finally, our local species and countless others from similar rainfall zones (around 250mm per year) should go together. In theory these plants would be happy growing on nothing more than natural rainfall, which is quite achievable for revegetation projects. However most will respond dramatically to the occasional watering. Something like one or two waterings all year is often enough to keep these dry land plants not only in healthy growth but also flowering for extended times and often in spectacular fashion. Anybody that has travelled to any of our Australian deserts after rainfall events will attest to it.
Make your plant choices wisely, water wisely and be rewarded for your efforts without having to ‘chase the bugs’!
This article first published in the Riverland Weekly © November 13, 2008.