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Growing tomatoes in pots in Brisbane: timing, pots and fruit fly

Tomatoes are the plant almost everyone wants to grow, and the one that frustrates Brisbane gardeners most often. Plants look great, flower, and then the fruit splits, rots or gets stung by fruit fly. Most of these problems come down to timing and a few simple habits.

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Timing matters more than anything

In cooler parts of Australia, tomatoes are a summer crop. In South-East Queensland, mid-summer is actually the hardest time to grow them. Very hot days and warm, humid nights can stop flowers setting fruit, fungal leaf diseases spread quickly, and Queensland fruit fly is at its most active.

The more reliable windows for SEQ are:

You can plant in October, but choose cherry tomatoes, which handle heat and humidity much better than big slicing varieties, and expect the crop to slow as summer arrives. If you're in October now, the October planting guide lists other crops that suit the season.

Choosing a variety for pots

Pot size

Tomatoes are thirsty, hungry plants, and a pot that's too small is the most common cause of trouble. Small pots dry out fast, which leads to stressed plants, split fruit and blossom end rot.

Use a good-quality potting mix rather than garden soil, and leave a few centimetres at the top for mulch. The guide to potting mix for Brisbane heat explains what to look for on the bag.

Sun, wind and support

Tomatoes need at least six hours of direct sun to fruit well. In spring and autumn, give them the sunniest spot you have. In the hottest months, a little afternoon shade can help.

Put in support when you plant, not later, so you don't damage roots. A tomato cage suits bushy cherry types, while tall types are easier on a sturdy stake. Tie stems loosely with soft plant ties so they don't cut in as the plant grows. On high, windy balconies, a lower-growing variety in a heavy pot is often the better choice.

Watering: consistency is everything

Uneven watering causes most fruit problems in potted tomatoes:

Check pots daily in warm weather using the finger test, and water deeply when the top few centimetres are dry. Mulch helps a lot. If you're often away, tomatoes are one of the crops where self-watering pots really earn their keep. Avoid wetting the leaves, especially in the evening, because it encourages disease. The watering mistakes guide has more on this.

Feeding

Tomatoes need steady feeding in pots. A common mistake is giving them too much nitrogen, which produces a big leafy plant with few flowers.

Pollination on a balcony

Tomato flowers mostly pollinate themselves, but they need a little movement to release pollen. Outdoors, wind and bees usually do this. On a sheltered balcony, gently tapping or shaking the flower trusses every day or two while they're open can improve fruit set.

Queensland fruit fly

Queensland fruit fly lays eggs in ripening fruit, and the larvae turn it to mush from the inside. Small puncture marks on the skin are often the only sign until you cut the fruit open. Ways to manage it in pots:

Leaf diseases

Humidity encourages fungal leaf spots and blights, which usually start on the lower leaves as yellow patches with brown spots. To reduce problems:

Quick checklist