How to plant tomatoes

Choosing the right tomato seeds

Tomatoes are one of the easiest fruits to grow from seed. The hardest part is choosing which type of tomato you want to grow.

Tip: Look for tomato varieties that are bred to be disease-resistant.

Cultivating tomato seeds

It’s best practice to start planting your tomato seeds in late winter. Check when the last frost usually hits your area. You’ll need to begin the process six to eight weeks before this.

Place some free-draining, sterile seed potting soil into a seed tray. Make a trail with your finger and pop the seeds in. Cover these with about 6mm of soil.

You’ll need to keep the seeds consistently moist and warm (around 21 to 27 degrees Celsius) to help speed up seed germination. Place your seed tray near a sunny window or on top of a heat mat, or use grow lights. Give your seedlings a daily mist to keep the humidity up.

Once your seedlings have become established, you’ll need to thin your tomatoes. This means selecting the best of the bunch and discarding the rest. Choose the healthiest, strongest seedlings with sturdy stems and use a pair of scissors to snip off the other unwanted seedlings at soil level.

When these remaining seedlings develop strong stems, a good set of true leaves (subsequent leaves that grow after the first two leaves on your tomato seedling), and are at least 10cm to 15cm tall, they are ready to be hardened off. This means slowly introducing them to outdoor conditions so they can get accustomed to sun, wind and changing temperatures.

Place them outside for a few hours at a time, gradually increasing the time over seven to 10 days. Once this is done, your seedlings are ready to be planted into the ground. Prepare a planting area for your seedlings by mixing in some good organic matter like compost or well-rotted manure into the soil. Once the last frost has passed, plant your seedlings in a sunny position and water with diluted liquid fertiliser and a seaweed tonic. If everything goes well, you can expect to harvest your first tomatoes in about eight weeks.

Planting established tomatoes

If you prefer to plant established tomato plants, head in-store to select your tomatoes. The best time to start planting tomato plants is during the summer when the soil is warmer. This will maximise the growing season and avoid any potential frost damage. Alternatively, you can start a little earlier in spring once the last frost has passed. Select a sunny, spacious area in your garden that receives at least six to eight hours of full sun daily.

When you’re ready to plant, prune the tomato plants’ lowest leaves. Dig a hole the size of the root ball of each plant. Make sure the hole is at least halfway up the plant’s stem. Tomatoes prefer to be planted quite deeply, as the buried stem will naturally produce extra roots to anchor your plant down.

Place the plant gently in the hole and fill with soil. Water thoroughly after planting with a water and plant-start solution to settle the soil and help the seedlings get comfortable. Apply a 10cm layer of organic mulch right up to the stem to conserve moisture and warmth and to help keep weeds at bay.

Set up any stakes, trellises or cages to support your tomatoes’ growth. Doing this now will help avoid potential root damage down the line. Drive the stake in at least 30cm and position it about 12cm away from the plant. Secure the plant to the stake with some twine or string, adding additional ties every 15cm to 20 cm as they continue to grow.

Spacing tomato plants

Make sure you check the maximum plant height of your selected tomato variety; you can usually find this on the seed packet or plant label. A general rule of thumb for smaller varieties is to plant them 60cm apart, while larger ones can be anywhere from 90cm to 1m apart. Tomatoes love to breathe and the better the air circulation, the less likely you are to get humidity-related pests and diseases.

Now that your tomatoes have been planted...

Learn how to maintain healthy tomatoes.