Try not to leave water on the leaves of plants which are susceptible to fungal diseases, for example tomatoes, cucumbers, pumpkins, zucchinis. Preferably water with drippers, or if you must use overhead sprinklers, water in the cool of the morning so that the water can evaporate during the day. Remember to leave space in your vege patch for those winter vegetables which must be planted in late summer - early autumn. Brassicas and other winter crops need time to mature before the extreme cold of winter sets in. They compete with your plants for food, water and sunlight.
Pests can multiply rapidly over summer.
Observe if there are natural predators present, remembering that there will be a delay between the appearance of the pest and the subsequent build-up of its predators. If you must spray, then use an environmentally benign spray. Reads books on this subject such as Jackie French's Natural Pest Control . Make sure that you harvest your crop regularly - in most cases this will encourage your plants to continue cropping, and you get to eat your produce at its peak. This table is a guide only, please observe the seasonal weather patterns before deciding when to plant, as there will often be distinct differences in summer weather from one year to the next.