From seed to juicy fruit: your step-by-step guide to growing garden-fresh tomatoes bursting with flavour.

There’s nothing quite as exciting as presenting a plateful of homegrown tomatoes at a summer party. Whether you’re making a Caprese salad, pan con tomate, or a fat slice of beefsteak tomato on sourdough, the vibrant flavour and sun-ripened sweetness of your own harvest will steal the show.

Tomatoes are medium-demand plants that don’t require much more than a good feed and plenty of sunshine. But in Tasmania, chilly nights and late frosts can set your plants back. The secret to growing great tomatoes is knowing your microclimate, choosing varieties that thrive in your region, and setting them out at just the right time.

Determinate vs Indeterminate

Tomato varieties fall into two categories: determinate or indeterminate. Determinate varieties tend to set their fruit all at once and then taper off, while indeterminate varieties continue to fruit until the first frost.

We stock the following varieties in store. Please note all height measurements are estimates, and the following list does not reflect stock availability. Call us at 03 6228 7705 to check if your favourite tomato varieties are in store.

Sowing tomatoes from seed

The last week of August through September is the best time to start tomato seeds indoors by a sunny window or in a warm spot, such as the top of the fridge or a hot water cylinder. Sow seeds in a friable seed-raising mix and keep the soil moist until they sprout, usually within 7–10 days.

You can prick out tomato seedlings while they’re still small, being careful not to touch the stems or roots, and pot them up. With plenty of water and a dose of liquid feed, they should be ready to begin hardening off in mid- to late October.

Hardening off seedlings

Seedlings need to be hardened off to build strength and resilience, helping them withstand local weather conditions. Begin by placing them in a shaded or semi-shaded position with exposure to a light breeze. Bring them indoors at night to protect them from critters and cold temperatures. After a few days, you can slowly introduce them to sunnier conditions.

When to set out tomatoes

There’s a well-loved Tasmanian tradition of planting tomatoes on Show Day, but the right timing really depends on where you live. Aim to plant when night-time temperatures are consistently above 12°C and soil temperatures are sitting at or above 16°C. If frost is still likely in your area come the last weekend of October, you’ll do yourself (and your tomatoes) a big favour by waiting another couple of weeks.

Planting your tomatoes

Tomatoes can grow adventitious roots from their stems, so they benefit from being planted deeply — up to half the height of the plant. This encourages a stronger root system and creates a sturdier plant that can better withstand Tasmanian summer winds. Deep planting also protects roots from temperature fluctuations that can stress young seedlings.

Watering your tomatoes

Before planting, make sure your garden bed or potting mix is well-watered. Once your seedlings are in, water them in thoroughly to help them establish. Tomatoes aren’t drought-tolerant and can become stressed by inconsistent watering, so aim to keep the soil consistently moist. Watering at the base (rather than overhead) helps keep foliage dry and disease-free.

Feeding your tomatoes

Tomatoes have a short growing season in Tasmania. Because they need to establish and fruit within 3-4 months, fertilising is key. Start seedlings with a fortnightly liquid feed of seaweed tonic and liquid fertiliser. By the time they’re planted out, garden beds or pots should be enriched with a generous helping of nitrogenous fertiliser to encourage rapid growth. As the weather warms in November, continue feeding your tomatoes with a side dressing of nitrogenous fertiliser and sulphate of potash until flowering begins. Once flowers start to set fruit, switch to phosphorous-rich fertilisers to support fruit development and reduce excess leafy growth.

Essential tomato products in store

Common tomato problems

Leggy seedlings

Tomatoes grown indoors from seed can become leggy if they don’t receive enough sunlight. To strengthen them, crack open a window to allow a breeze or set them outside on a mild day. This will help the stems toughen up. If they’re still leggy at planting time, plant them deeply at a 45-degree angle. The plant will straighten itself out as it grows.

Aphids

These sap-sucking insects tend to attack weak plants and are usually only a problem when plants are young. You can sprinkle diatomaceous earth directly on aphids, spray plants with an oil-based insecticide, such as white oil or eco-pest oil, or simply pick them off. Consider planting flowers, such as marigolds and nasturtiums, alongside your tomatoes to attract predatory insects that feed on aphids.

Curling leaves

Tomatoes do best with consistent watering. If a large amount of water is added to parched soil, the plants may temporarily curl their leaves. This generally won’t harm them and is simply a symptom of inconsistent moisture. It’s a common occurrence in summer, especially when many of us are away on Christmas holidays and rainfall is less likely. If you’re planning to leave your tomatoes for a few days, consider investing in a watering timer or mulching your beds heavily.

Blossom-end rot

If you notice a black, rotting spot on the underside of your tomatoes as they begin to ripen, you’re likely dealing with blossom-end rot. This is usually a symptom of calcium deficiency, which can result from irregular watering. The best cure for blossom-end rot is prevention, ideally addressed before planting. Ensuring your tomatoes are growing in nutrient-rich soil, with plenty of organic matter and trace minerals added at planting, will reduce the likelihood of this issue, as will maintaining a consistent water supply. If blossom-end rot has already appeared, try adding gypsum or a complete organic fertiliser to the root zone of affected plants.

Come in to the Nursery and talk to one of our friendly garden experts today!