Tomato flowers need to be pollinated to form fruit. Flowers are pollinated by wind or special insects like the Australian native blue-banded bee. Planting lots of flowers in your garden that attract beneficial pollinating insects can help improve Tomato fruit set, as can growing plants in an airy position. You can even try hand-pollination (with a small paintbrush) or gently shaking the plants to help move pollen around between flowers.
Cold temperatures can cause blossom drop (therefore affecting fruit set), however once the weather warms up, more flowers will develop and hopefully fruit will follow. In addition, cold weather can lead to a problem called ‘cat-facing’, where fruit develops abnormally and appears dimpled and scarred. Improved weather conditions will result in less cat-facing.
Prolonged very hot weather can also lead to blossom drop. Try creating a shade structure to help protect your Tomato plants from harsh sun.
Well-fed and watered plants will produce more fruit, so regular watering and feeding is important.
For more information, visit our comprehensive guide on How to Grow Tomatoes in a vegie patch or pots.