Some gardeners have difficult issues with tomato diseases, especially fungal wilts. If this is happening to you then grow tomatoes that are bred to resist these diseases. They are often F1 cultivars so it is not possible to later collect your own seed and expect plants to grow true to type, but it can be worth it just to get a decent crop each year. Fermenting your seed before drying, can also reduce disease (see below).
Fermenting tomato seed before drying will kill any diseases on the seed or in the seed coat. Spoon the pulp with seeds into a cup and add a little water. Leave to sit in a warm spot (but out of direct sunlight) until the seeds start to ferment leaving a smelly white scum on the top. This will take 1–5 days depending on the temperature. Strain the seeds through a fine sieve rinsing well with water and discarding the scum. Spread the seeds over a plate to dry, then place in an envelope with the name and date. Store in a cool, dry position.
Cool and arid climate growing tips
Soil needs to be about 18oC before seeds will germinate. Sow seed into punnets or small pots in a warm position inside or outside. Once big enough to transplant easily, remove the lowest pair of leaves and plant into slightly acidic, composty soil that is well drained and in full sun. Alternatively, you can transplant seedlings into bigger pots and plant out later. Either way, position them so that the lower stem is buried. Provide support for all the taller-growing ‘staking’ cultivars with stakes, screens or frames. Once growing strongly, prune around the base to leave a space between the soil and the bush. Mulch well and water regularly, avoiding soil splash. Sprinkle the soil around plants with potash to promote flowering.
Warm climate growing tips
Our tropical expert Leonie Shanahan says that only die-hard gardeners in tropical and subtropical regions would try to grow big tomatoes during summer, mostly because of fruit fly problems. But cherry tomatoes can thrive, especially those like Tommy Toe, Yellow Pear, Thai Pink Egg and Tropic. She adds that you can cover your crop with white shadecloth or vegie net to lessen fruit fly impact and that plants definitely need good air circulation. She suggests planting in pots with a trellis so they have good drainage and airflow. In good-quality potting mix, soil-related diseases are less likely. A bigger range of tomatoes can be grown if they are planted in autumn and grown through winter.
For more great information on tomatoes, from heirlooms to top tasters and more, get your copy of ABC Organic Gardener magazine, Issue 90.
By: Penny Woodward
First published: October 2016