Growing tomatoes from seeds can be a rewarding experience, providing you with delicious, fresh fruits all summer long. Whether you’re a seasoned gardener or a beginner, this comprehensive guide will walk you through everything you need to know about how to grow tomatoes from seeds, from choosing the right varieties to dealing with common problems.
Getting Started: How to Grow Tomatoes from Seeds
Choosing the Right Tomato Variety for Growing from Seeds
There’s an enormous range of tomato varieties to choose from, which is one of the great benefits of growing your own tomatoes from seeds. Tomatoes come in various sizes, colors, textures, and flavors, far more diverse than what you typically find in supermarkets. You can grow small cherry tomatoes, medium-sized salad tomatoes, or large beefsteak varieties. Each type has its unique characteristics and growing requirements.
Understanding Cordon and Bush Tomatoes
Tomatoes generally have two different ways of growing:
- Cordon (or Indeterminate) Tomatoes: These are vigorous, fast-growing plants that can get very tall and need suitably tall supports, both in a greenhouse and outdoors. As they grow vertically, they take up very little ground space. However, they require regular maintenance, including watering, feeding, tying to supports, and removing side-shoots.
- Bush (or Determinate) Tomatoes: These are naturally more compact plants, making them great for smaller spaces. Trailing types can also be grown in window boxes and hanging baskets, with the stems cascading over the sides. These are the easiest type to grow and need little maintenance apart from watering and feeding. The stems may need support when heavily laden with fruit.
Check seed packets or plant labels before buying to ensure you get the type that suits your growing space.
Starting from Seed vs. Buying Young Plants
Tomato seeds are widely available from garden centers and other seed stockists. Many also sell young plants in spring and early summer. These are ideal if you don’t have the time or space to grow from seeds, but the choice of varieties is limited. Grafted plants are a recent introduction – these are generally more vigorous than seed-grown plants, providing earlier and larger crops and greater resistance to disease. However, they are more expensive, and the choice of varieties is currently fairly small. Grafted plants are mainly available from online suppliers.
Sowing Tomato Seeds
Growing tomatoes from seeds indoors is straightforward. Sow from late February to mid-March if you’ll be growing your crop in a greenhouse, or from late March to early April if they’ll be outside. Seeds need a temperature of about 18°C (64°F) to germinate, so use a heated propagator or place the pots on a warm windowsill and cover them with a clear plastic bag to maintain humidity. As soon as seedlings appear – usually within a fortnight – uncover and place them in as much light as possible to prevent them from growing thin and leggy.
Pricking Out and Potting On
After a couple of weeks, once the seedlings have a couple of true leaves, move them into individual pots or modules of peat-free multi-purpose compost. Lift each seedling individually, using a dibber to support its rootball, and hold it by a leaf rather than the delicate stem. If the seedling is leggy, replant it more deeply, so the first pair of leaves is just above the compost surface. Keep them in a bright location, with a temperature of at least 16°C (60°F), and water regularly. After about a month, they should be ready to plant in their final position.
Planting Out Tomato Seedlings
Young, well-rooted tomato plants, either grown from seeds or recently bought, can be planted into their final position in early summer once temperatures are reliably above 16°C (60°F). You can plant them in large containers or growing bags in a greenhouse or outdoors, or plant them in the ground. To grow outdoors, choose a really warm, sunny, sheltered location.
Plant tomatoes deeply, so the first set of leaves is just above the soil surface – the buried section of the stem will then produce additional roots. Tomatoes are tender, so before planting out, acclimatize them to garden conditions by hardening off.
Grow Tomatoes in Containers
Tomatoes do well in large containers and growing bags in a greenhouse or outdoors in full sun, and they are very productive in a small space. Use peat-free loam-based or multi-purpose compost. Plant one tomato plant in a 30–45cm (12–18in) pot and two in a standard growing bag.
- Bush types are compact and ideal for large patio containers, troughs, window boxes, and even hanging baskets.
- Cordon types grow well in large containers, with a tall cane for support. This can make the pots top-heavy, so position them in a sheltered site, ideally against a sunny wall. In a greenhouse, you can use canes or vertical strings for support – tie the strings to the roof, so they hang down vertically, and bury the other end under the rootball when you plant. The string should be quite slack, so it can be wound around the top of the main stem as the plant grows.
Grow Tomatoes in the Ground from Seeds
Tomatoes thrive in rich, free-draining but moisture-retentive soil, so add plenty of garden compost before planting. Choose your warmest, sunniest spot, sheltered from the wind. Space plants 45–60cm (18–24in) apart, depending on their eventual size – check seed packets for exact spacings. With cordon tomatoes, insert a sturdy cane next to the plant and tie in the main stem loosely.
Avoid growing tomatoes in the same bed in consecutive years to prevent the build-up of diseases in the soil. Alternatively, you can use a growing method called ring culture in a greenhouse border.
Caring for Your Tomato Plants
Watering Your Tomato Plants
Water tomato plants regularly to keep the soil or compost evenly moist. Fluctuating moisture levels can cause problems with the fruit, such as splitting or blossom end rot. Plants in containers dry out quickly, so they may need watering daily in hot weather. Curling leaves can be a sign that a tomato plant is short of water.
Top Tip: Sink a 15cm (6in) pot into the ground alongside tomato plants and water into it, so the water goes directly down to the roots. The moisture doesn’t then sit around the neck of the plants, which can lead to rotting.
Feeding Your Tomato Plants
To boost fruiting, especially with plants in containers, feed every 10–14 days with a high-potassium liquid fertilizer once the first fruits start to swell.
Mulching Your Tomato Plants
Lay a thick layer of mulch over the soil around tomato plants to help hold in moisture and deter weeds. Use garden compost or well-rotted manure, but leave a gap around the base of the stem to prevent rotting.
Improving Pollination
When growing tomatoes in a greenhouse, open the vents regularly to give pollinating insects access to the flowers. You can also lightly tap or shake the flowers when fully open to aid pollen transfer within the flower. Misting flowers with water may also help.
Pruning and Training Tomato Plants
The two different types of tomatoes are treated differently – check your seed packet or plant label to see which type you are growing:
- Cordon Tomatoes: These are grown as tall, single-stemmed plants. They need tall supports, and the side-shoots should be removed regularly. This keeps these vigorous plants in check and ensures they put their energy into fruit production.
- Bush Tomatoes: These are more compact, and their side-shoots should be left to grow. Plants may need support if they grow quite large. Also, if they carry a heavy crop of tomatoes, the side-shoots may start to droop or be at risk of snapping. If so, simply add short vertical canes when and where required, tying in the shoots loosely.
Training Cordons Up Supports
Cordon tomatoes need support, usually either a tall sturdy cane or a vertical string coming down from an overhead horizontal support, such as a greenhouse roof, and anchored under the plant’s rootball at planting time. However, tomatoes don’t cling to supports or twine around them naturally, so they must be attached by hand as they grow. If using a cane support, simply tie the main stem to it at regular intervals as it grows. If using a vertical string, gently wind the string around the top of the main stem once or twice a week as it grows.
When plants reach the top of their support or have set seven fruit trusses indoors or four trusses outdoors, remove the growing point of the main stem at two leaves above the top truss.
Removing Side-Shoots
Cordon tomatoes are best grown as single-stemmed plants. However, these vigorous plants naturally produce side-shoots from the joints where leaves sprout from the main stem. These side-shoots should be removed to keep plants growing vertically on just one stem. If they’re not removed, the side-shoots grow rapidly, forming a mass of long, scrambling, leafy stems that are difficult to support, produce few fruits, and take up a lot of space.
Removing the side-shoots is simple – every time you water, check the plant for any shoots sprouting from the joints between the main stem and leaves. Snap them off with your fingers. Don’t cut them, as the wound may become infected.
Bush tomatoes naturally branch and don’t need side-shoots removed. Simply let them grow, although if plants become top-heavy with fruit, tie them to short vertical canes for support.
Pinching Out Tips
To speed up ripening in late summer, pinch out the growing tip of the main stem and any side-shoots about a month before the first expected frost, leaving about four trusses of fruit on the plant. This stops the plant from flowering and setting more fruit, concentrating its energy on the remaining trusses.
Q&A Section on How to Grow Tomatoes from Seeds
Q: How long does it take to grow tomatoes from seeds?
A: To grow tomatoes from seeds to harvest typically takes about 70-85 days, depending on the variety and growing conditions.
Q: Can you grow tomatoes from seeds indoors year-round?
A: While tomatoes can be started indoors year-round, they need sufficient light and warmth. Using grow lights and maintaining a warm environment can help achieve this.
Q: What are the common problems when growing tomatoes from seeds?
A: Common problems include damping-off disease during germination, leggy seedlings due to insufficient light, and transplant shock. Ensuring proper care and conditions can help mitigate these issues.
Q: How often should I water my tomato seedlings?
A: Tomato seedlings should be watered regularly to keep the soil moist but not waterlogged. Overwatering can lead to root rot, so ensure good drainage.
Q: What is the best time to transplant tomato seedlings?
A: Transplant tomato seedlings when they have at least two sets of true leaves and after the risk of frost has passed, ensuring temperatures are consistently above 16°C (60°F).
Growing tomatoes from seeds is a rewarding and enjoyable experience that can provide you with a bountiful harvest. With the right care and attention, you can enjoy delicious, home-grown tomatoes all summer long.