One thing we have tried to do is keep our garden organic. So naturally we avoid the use of pesticides. One way of doing this is to use companion planting. Companion planting is interesting and fun to do with often visually beautiful results. Companion planting gives you the freedom to mix and match flowers, veges, herbs and fruit trees. There are a few approaches to it, for example, you can plant shallow and deep rooted plants together like lettuce and spinach (both shallow rooted light feeders) and celery, carrots, corn and parsnips (deep rooted and heavy feeders). Another way to companion plant is to grow plants together that have different germination times, so, you can grow radishes with carrots because the radishes are quicker to germinate and they help keep the soil soft for the slower growing carrots. Strong odoured plants can either attract or repel insects (or "pests"), for example, we have grown nasturtiums under banana trees with good repelling effects and basil near tomatoes which also work well to repel insects. Rosemary and the mints are also good repellers. Flowers will tend to attract the more garden friendly bugs and we have planted our favorites like ground dwelling gardinias, rampling geraniums and camomile.
Chemicals excluded from roots can work either to prevent germination or to inhibit the plants growth. For example, all the members of the onion family retard the growth of peas and beans while marigolds have a chemical coming from their roots and leaves that can help deter pests. Chives around the rose bush can help to deter aphids and shade the soil as well. Confusing predators by planting a range of flowers that have different smells and that flower at different times or have similar shapes and sizes can make it so you can hide certain plants from the insects view or attract them elsewhere. This can work really well because the garden is so full of choices for these bugs that they leave their normal target plants alone. A variation on this theme is to always let some of your veges go to seed to attract insects to this plant and not other and if bugs do find and destroy one plant in the vege patch just let them go for it, it works well .
