Tomatoes are a beloved staple in many gardens, prized for their juicy, flavourful fruit that enhances countless dishes. Their vibrant colours and rich tastes make them a favourite for everything from fresh salads to hearty sauces!
Whether you're a seasoned gardener or a beginner, growing your own tomatoes can be incredibly rewarding; imagine stepping out into your garden and picking a sun-warmed, vine-ripened tomato to add to your meals. It's a simple pleasure that can elevate your culinary creations to the next level.
In this guide, we’ll explain how to grow tomatoes from seeds, whether you have a sprawling backyard garden or a raised garden bed on your balcony. We’ve got all the tips and techniques to ensure your tomato plants thrive.
Choosing the right tomato variety for your garden
The first step in growing tomatoes is selecting the right variety for your garden. Tomatoes come in two main types: determinate and indeterminate:
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Determinate Tomatoes: These are bush-type tomatoes that grow to a certain height, produce fruit all at once, and then stop growing. They’re ideal for small spaces or container gardening. Popular varieties include 'Roma', 'Celebrity', and 'Bush Early Girl'.
- Indeterminate Tomatoes: These vine-type tomatoes continue to grow and produce fruit throughout the growing season. They need staking or caging for support. Favourite varieties include 'Beefsteak', 'Cherry', and 'Heirloom'.
When choosing your tomato variety, consider your space, growing conditions, and how you plan to use your tomatoes. For example, if you’re growing tomatoes in a raised garden bed, you might opt for determinate tomatoes because they only grow to a certain height, allowing you to maximise space on your balcony or patio.
Preparing the soil for your tomatoes
Tomatoes thrive in well-draining, nutrient-rich soil; proper soil preparation is crucial for healthy growth and a bountiful harvest. To get started, test the soil’s pH. Tomatoes prefer acidic soil with a pH of 6.0 to 6.8 — if it’s too acidic (below 6.0), add lime to raise the pH, and if it’s too alkaline (above 6.8), add sulphur to lower it.
You can purchase a soil test kit from your local nursery or Bunnings!
Here are some other tips for preparing soil.
Enrich the soil
Tomatoes are heavy feeders, so enriching the soil with organic matter is key. Mix in plenty of compost to improve soil structure, fertility, and drainage, as well as well-rotted manure to boost nutrient levels. Organic amendments like bone meal (for phosphorus) and wood ash (for potassium) can also improve soil fertility.
Consider a raised garden bed
If your garden soil is heavy clay or poorly drained, a raised garden bed is the perfect solution. Raised beds offer better drainage, improved soil aeration, and warmer soil temperatures, which are ideal conditions for tomato plants.
Fill your raised beds with high-quality garden soil mix and equal parts of topsoil, compost, and well-rotted manure to improve drainage further.
Moisture, aeration & tilling
After planting your tomato seeds, apply a layer of mulch to help retain soil moisture, suppress weeds, and regulate soil temperature.
Ensure the soil is well-aerated by loosening it with a garden fork or tiller before planting. Avoid over-tilling — this can disrupt the soil structure and harm beneficial organisms.
Key planting techniques
Properly planting your tomatoes will set the foundation for strong growth and fruit production. Spacing is essential to ensure your tomato plants have enough room to grow and access sunlight, air, and nutrients:
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Determinate Varieties: These bush-type tomatoes should be spaced about 18-24 inches apart. Determinate tomatoes grow to a certain height, produce fruit all at once, and then stop growing; adequate spacing helps prevent overcrowding and ensures good air circulation, reducing the risk of disease.
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Indeterminate Varieties: These vine-type tomatoes require more space, with plants spaced 24-36 inches apart. Indeterminate tomatoes continue to grow and produce fruit throughout the season. Providing enough space allows for proper support structures like stakes or cages and ensures the plants get ample sunlight and air circulation.
- Row Spacing: Space rows about 36-48 inches apart. This allows you to move between the rows for maintenance and harvesting and provides additional airflow, which is crucial for preventing fungal diseases.
Aside from spacing, water your seeds after planting to settle the soil and eliminate air pockets. Keep the soil consistently moist (but not waterlogged) until the plants are established.
The timing of planting tomatoes is also critical to success. For example, tomatoes are warm-weather plants and highly sensitive to frost, so plant them after the last frost date in your region. You can find this information from local nurseries (or a quick Google will suffice).
Ensure the soil is consistently above 15 degrees before planting, too. Cold soil can stunt growth and make your tomato plants susceptible to diseases. Use a thermometer to check the temperature.
Supporting your tomato plants as they grow
Supporting your tomato plants is essential, particularly if you prefer a low-maintenance approach. There are three options available: staking, caging, and trellising.
Staking
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Materials Needed: Use 6-8 foot tall stakes made of wood, metal, or sturdy bamboo. Ensure the stakes are strong enough to support the weight of mature plants and their fruit.
- Installation: Drive the stake into the ground about 6 inches from the plant’s base. Insert the stake at least 12-18 inches deep to provide stability. Install the stakes at the time of planting to avoid damaging the roots later on.
- Tying the Plant: Use soft ties like cloth strips, garden twine, or commercial plant ties to attach the main stem to the stake. Begin tying the plant when it is about 12 inches tall, making a loose figure-eight loop to avoid constricting the stem. Continue tying the plant at regular intervals as it grows, ensuring the ties are secure but not too tight.
- Pruning and Training: Regularly prune the plant by removing the suckers (the small shoots that develop in the leaf axils) to encourage vertical growth and reduce the weight on the stake. Training the plant to a single stem makes it easier to manage and supports better air circulation.
Caging
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Choosing a Cage: Select a sturdy, galvanised wire cage with a diameter of at least 18-24 inches and a height of 4-6 feet. The cage should have large openings to allow for easy access to the plant and its fruit.
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Installation: Place the cage over the plant shortly after planting, pushing the legs of the cage into the soil to anchor it securely. Install the cage early to prevent damaging the plant’s roots and to guide the plant’s growth from the beginning.
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Growth Through the Cage: As the tomato plant grows, guide the branches through the openings in the cage. This helps support the plant’s weight and keeps the branches from sprawling on the ground.
- Minimal Pruning: Unlike staking, caging requires minimal pruning. The cage provides support for multiple stems, allowing the plant to grow more naturally. However, removing the lower leaves and any diseased or damaged foliage is still beneficial.
Trellising
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Materials Needed: Use a strong trellis system made from wooden or metal posts with horizontal wires, netting, or a lattice structure. Ensure the trellis is tall and sturdy enough to support the mature plants.
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Installation: Install the trellis at the time of planting. Space the posts about 6-8 feet apart, and secure the horizontal wires or netting at various heights to provide multiple support points.
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Tying and Training: Similar to staking, tie the main stem to the trellis using soft ties. As the plant grows, train the branches to spread out along the trellis, attaching them at regular intervals.
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Pruning and Maintenance: Regularly prune the plant to encourage vertical and lateral growth along the trellis. Remove any suckers and ensure good airflow by spacing out the branches.
Regardless of which option you choose, it’s important to regularly check the ties and supports to ensure they’re holding up well and adjust them if needed. Loosen any ties that are becoming too tight to prevent damage to the stem.
At the end of the growing season, remove the supports and clean them. Store them in a dry place to prevent rust or damage, ensuring they’re ready for the next growing season.
Pest & disease management
Tomato plants attract several pests that can damage the leaves, stems, and fruits, like aphids — small, soft-bodied insects that cluster on the underside of leaves, sucking sap and weakening the plant. They excrete a sticky substance called honeydew which can lead to mould growth.
Spray aphids with a strong jet of water to dislodge them. Introducing beneficial insects like ladybugs (the natural predator of aphids) can help keep their population in check.
Other pests include:
Hornworms
These large green caterpillars defoliate tomato plants, leading to significant damage. They also blend with the foliage, making them extra hard to spot!
Handpick them off the plants and dispose of them. Use a biological insecticide to control larvae, and encourage natural predators like birds and wasps to help manage the population.
Spider mites
These pests can cause stippling and yellowing of leaves, leading to reduced plant vigour. They thrive in hot, dry conditions.
Introducing predatory mites can help manage spider mite populations. Alternatively, you can spray them with water to dislodge them or use an insecticidal soap.
Cutworms
These nocturnal larvae can cut off young seedlings at the soil line. Use collars made from cardboard or plastic around the base of your seedlings to prevent cutworm damage, and remove plant debris and weeds where cutworms might hide.
Tomatoes are also prone to several fungal, bacterial, and viral diseases. Here are some tips on how to prevent and control common tomato diseases found in Australian gardens:
Fungal diseases
Fungal infections like blight, mildew, and leaf spots are common in tomatoes. These diseases thrive in humid conditions and spread quickly.
Here are some preventative measures you can take to avoid these diseases:
- Practice crop rotation
- Remove and destroy infected plant debris
- Space plants apart for good air circulation
- Avoid overhead watering
- Apply appropriate fungicides as needed.
Bacterial diseases
Bacterial infections like citrus canker can cause wilting, leaf spots, and stem lesions.
- Use certified disease-free seeds and transplants.
- Avoid working in the garden when plants are wet to prevent the spread of bacteria.
- Remove and destroy infected plants.
- Copper-based bactericides can help manage bacterial diseases.
Viral diseases
Viral infections such as tomato mosaic virus and tomato spotted wilt virus cause mottled leaves, stunted growth, and reduced fruit quality.
- Use virus-resistant varieties.
- Control insect vectors like aphids and thrips that spread viruses.
- Remove and destroy infected plants to prevent the spread of the virus.
Companion plants to successfully grow tomatoes
Choosing the right companion plants can boost your tomato harvest by improving pollination, deterring pests, and enhancing soil health. Basil is a classic pairing—it may help repel insects like aphids and whiteflies while improving flavour. Marigolds are another favourite, known for keeping nematodes and other soil pests at bay.
You can also plant tomatoes alongside carrots, lettuce, spinach, and onions to make the most of your garden space. Avoid growing them near brassicas (like broccoli or cabbage) and corn, which can compete for nutrients or attract unwanted pests. With the right companions, your tomato plants will thrive naturally and productively.
Harvesting your tomatoes
Knowing how and when to harvest tomatoes is essential for the best flavour and texture! Proper harvesting techniques can also help maintain the health of your plants, encouraging continuous fruit production throughout the growing season.
Your tomatoes are ready to harvest when:
- They are fully coloured (depending on the variety). For example, red tomatoes should be a deep, vibrant red. Always refer to the seed packet or plant label for specific ripening indicators.
- They feel slightly firm but yield to gentle pressure. Overly soft tomatoes may be overripe, while hard tomatoes may be underripe.
- They have a sweet, earthy aroma at the stem end. This scent is a good indicator of ripeness and flavour.
- They are smooth and free from blemishes. If the fruit feels too hard or has a green tint, it needs more time on the vine.
To avoid damaging the fruit or the plant:
- Gently grasp the tomato and twist it until it releases from the vine. Don’t pull too hard; this can damage the plant or cause unripe tomatoes to drop.
- Use garden scissors or pruning shears to avoid stressing the plan. Cut the stem about half an inch from the fruit.
- Check your tomato plants daily to encourage the plant to produce more fruit and prevent overripe tomatoes from attracting pests and diseases.
- Handle the fruit gently, as tomatoes bruise easily. Place them in a shallow basket or container to avoid stacking or bruising.
FAQs
Is growing cherry tomatoes different to regular tomatoes?
Smaller cherry tomatoes are generally easier and faster to grow than larger tomato varieties. They produce fruit more quickly, require less space, and are perfect for pots or small garden beds. However, overall care, such as watering, sunlight, and support structures, is quite similar.
Can I use regular potting mix to grow tomatoes?
Yes, you can use regular potting mix, but choosing one enriched with compost or adding organic matter yourself is best. Tomatoes are heavy feeders, so a nutrient-rich mix with good drainage will give your plants the best start.
How can I add extra nutrients to my soil?
You can add extra nutrients to your soil by mixing in compost, aged manure, crushed eggshells, or worm castings — all excellent natural nitrogen, phosphorus, and potassium sources. Organic fertilisers like seaweed solution or fish emulsion can also boost your plants during the growing season. Mulching with straw or sugarcane helps retain moisture and slowly improves soil quality as it breaks down.
How do I keep the soil moist?
To keep soil moist, water your plants regularly — ideally in the morning — and apply a layer of mulch like straw, sugarcane, or bark to slow evaporation. Choose well-draining soil that retains moisture without becoming soggy, and water deeply rather than frequently to encourage strong root growth. In hot or windy conditions, you may need to water more often.
My tomatoes never seem to go red. What do I do?
If your tomatoes stay green, they may need more consistent warmth, sunlight, or time. Tomatoes ripen best in temperatures between 20–25°C, so cooler weather can slow the process. Try pruning excess leaves to let more sunlight reach the fruit, and pick any mature green tomatoes to ripen indoors in a warm spot, away from direct sunlight but near bananas or apples to speed things up with natural ethylene gas.
Now you know how to grow tomatoes from seeds, it’s time to get growing!
From selecting the right varieties and preparing your soil, to providing proper support and managing pests and diseases, each stage is crucial for ensuring healthy, productive plants. Remember, gardening is both an art and a science, and every garden is unique. Don’t be afraid to experiment and adapt the tips above to suit your specific conditions and preferences.
Give your tomato plants the best start to life with a raised garden bed from the Organic Garden Co! Our designs ensure the soil is well-aerated and drained, creating the best conditions to grow healthy tomatoes.