How to grow tomatoes
Growing your own tomatoes is a fun project that allows you to reap lots of tasty rewards! Learn how to start growing tomatoes, including step-by-step instructions on how to plant tomato seeds and young plants, plus basic care tips on how to water, prune, and feed your tomato plants until they’re ready for harvest.
Tomatoes are one of the most popular fruits to grow, and it’s not hard to understand why. They’re versatile, come in endless colours, tastes and sizes, and are even more delicious warmed by the sun and picked fresh from the vine. It’s a taste you can’t beat! Plus, growing your own tomatoes means you can try lots of new flavours, smells, sizes and colours you can’t find in the shops. The best thing about growing tomatoes though, is they can be grown almost anywhere, no matter what size of outdoor space you have. This could be in the garden, a greenhouse, in pots, or even in hanging baskets.
While growing tomatoes from seed or seedling can be a lengthy process, it’s something any gardener – even beginners – can succeed in by nailing down the basics. Simply choose a sunny spot and your favourite tomatoes, from small cherries to big beefsteak types, and watch as they grow into ripe and juicy fruits to feast on from summer way into autumn.
When to plant tomatoes
Plant young tomato seedlings in an unheated greenhouse from mid-spring, but if you prefer to plant directly outside, wait until May or June. However, this is just a general rule. When you plant depends on what the weather is like where you live. Wait until all risk of frost has passed and nighttime temperatures are above 10°C before you plant anything outside. Sow tomato seeds indoors anytime between February and April.
Where to plant tomatoes
To get the most out of your tomatoes, you’ll need to plant them in a sunny spot in rich, nutrient dense, and well-draining soil. Tomatoes like warm, but not overly hot, temperatures. A greenhouse is the best place to grow tomatoes either from seed or as young plants, but if you don't have the space then a heated propagator or sunny windowsill will do just as good a job. If the weather outside is warm enough, a cold frame will also protect your tomato plants enough to allow you to grow outside.
Growing tomatoes from seeds
There’s no right or wrong way to start growing your own fruit and vegetables. It's entirely up to your preferences, as well as what space you have available. Not everyone can start sowing tomatoes from seed, or maybe you’d rather start with young plants since growing from seed takes a lot more work and time. Some great reasons to grow tomatoes from seed are you’ll have lots more unique varieties to choose from, it’s an interesting, fun and rewarding process, and it allows you to plan for and grow a much larger harvest.
Growing tomatoes from seeds: step-by-step guide:
Start sowing tomatoes seeds from February, or earlier if you’re growing in a greenhouse.
Fill a seed tray with free draining, slightly damp Dobbies peat-free seed sowing compost. Sprinkle seeds thinly onto the surface then cover with another thin layer of compost and water lightly. To save space you can sow the seeds into a couple of 7cm pots instead. Over the next few weeks, make sure the compost is kept moist but be careful not to overwater. Keep the seedlings at a temperature of around 18–21°C. Using our Dobbies heated propagator works best when sowing tomato seeds, but you can also grow them on a warm windowsill. Make sure to cover your tray or propagator with a plastic lid or clear plastic bag to retain heat and moisture.
Your seeds should germinate within 1–2 weeks. As soon as seedlings appear, remove the cover from the propagator and place them in as much sunlight as possible.
Once the seedlings have grown around 10cm tall and have developed a few leaves, it’s time to prick them out and pot them on. Prepare individual 7cm pots with multipurpose compost. You need one pot per tomato seedling. Use a dibber to gently tease the roots out of the original compost and carefully transfer the seedlings into the pots, holding them by the leaves and not the stem. Firm the compost and water lightly, protecting these pots from frost and cold winds either by keeping them indoors, or inside a greenhouse or cold frame.
When the seedlings have grown to 15cm and have thick stems, they’ll be ready to plant out in the garden into your beds or a bigger container, only if all risk of frost has passed (this will likely be around May). Before transferring outside, it’s important to harden off young plants off. This is when you move your plants outside for a few hours a day and bring them back inside at night to help them slowly get used to outside temperatures and conditions.
When ready to plant outside, choose the warmest, sunniest space sheltered from the wind. Check the tomato seed packet to get the right spacing when planting in the ground.
Growing tomatoes from seedlings
The quickest and easiest way to grow your own tomatoes is from developed seedlings, also known as young plants. Read our blog on how to plant young plants. You can choose from a variety of delicious tomato varieties in our extensive range of young fruit and vegetable plants.
These have been grown and nurtured by experts to give your plants the best start.
After you buy your young plants, remove them from the packaging as soon as possible and give them a water. These young plants will still be too small to plant outdoors or into a larger pot, so plant them into 9cm pots using Jack’s Magic all-purpose compost by Westland. Plant these up to the first 2 true leaves, then gently firm in. Water your pots well and place them in a warm sunny spot, keeping the soil moist but not soaking wet. In a few weeks they’ll be ready to plant in a permanent spot in the ground or container.
How to grow tomatoes in the ground
If you have the space and climate, tomatoes are a must-have in your vegetable garden. Here are the steps you should follow to begin growing tomatoes in the ground outside:
Make sure your tomato seedlings are hardened off properly by keeping them outside for a few hours a day, bringing them back inside at nighttime. Do this for a few weeks to complete the hardening off process. Take this time to plan the spacing of your tomatoes in your plot. Directions on how much space to leave between each plant can be found on the packaging, but in general there should be around 45cm between each plant, and 75cm between rows.
As your tomatoes grow, support them with canes or sticks as necessary.
Water the ground well, making sure to avoid wetting the leaves.
Carefully transfer each tomato plant into its newly prepared hole in the ground so that the last set of leaves sit just above the soil surface. Fill in any gaps with remaining soil.
Tomatoes prefer to be planted deeply, so dig large holes into the ground using a hand trowel. They’re also hungry plants, so add Westland bonemeal fertiliser into the soil before planting.
How to grow tomatoes in a greenhouse
Growing tomatoes in a greenhouse provides the ideal growing conditions for your plants and can even give you an earlier crop. Here are the simple steps to growing tomatoes inside a greenhouse:
Either sow tomato seeds in 7cm pots from February or plant young plants when they’re between 15–20cm tall into a greenhouse border, pots or grow bag, following the planting instructions detailed in previous sections.
If you’re growing in a container, limit to 2 tomato plants per pot, planted around 35cm apart. They’ll also need a lot more water, so make sure you’re checking on them daily and watering as and when required.
Be careful your greenhouse doesn’t get too hot, as tomatoes won’t thrive in temperatures above 27°C. Using a built-in thermometer in your greenhouse is an ideal way of checking the temperature, which should be around 21°C.
To deter pests and diseases, ventilate your greenhouse correctly by opening the vents or door.
How to grow tomatoes in a pot or hanging basket
To save space, grow tomatoes either inside or outside in hanging baskets or pots. Smaller tomato varieties like cherry tomatoes look amazing trailing down the sides of baskets, ready for picking and snacking on. Here’s how you can grow tomatoes in any kind of container:
Choose a container that’s at least 30cm in diameter. It’s up to you whether this is a patio pot or a hanging basket, but tomatoes are thirsty plants, so the bigger the container, the easier it is to keep the plants evenly watered.
Pick a tomato plant to suit your container. Go for bushy, upright varieties for patio pots, or trailing ones for hanging baskets.
Put a layer of stones or crocks (broken terracotta) at the bottom of the pot to help with drainage, then fill it with high quality multi-purpose compost.
Plant your tomatoes, leaving about 30cm of space around each plant. Planting tomatoes a few centimetres deeper than the top of the pot encourages the best growth. Firm plants into place with extra compost if needed. If planting in a basket, line the basket with natural fibre liner then fill with compost. Plant around the edge of the basket so the plants grow outwards.
Tomatoes love the sunshine, so position your container in the greenhouse or outside in a sunny, sheltered spot (once all risk of frost has passed).
As the plants grow, support their stems with a bamboo cane and tie as needed. How many tomatoes you can get per plant will vary according to variety, but some can grow up to 100!
When to harvest tomatoes
Your tomatoes will normally be ready to harvest between July and October. One thing to remember is that, depending on where you are in the country, these times will be slightly different. In areas with milder weather, the timescales may be a little earlier, and for those with harsher weather, it could be a little later.
You’ll know when it’s time to harvest your tomatoes by looking at and feeling them. They should have developed a deep colour when ripened and be easy to pluck from the vine. Later in the summer, any matured yet unripe tomatoes that are just starting to develop colour can still be picked and left to ripen inside your kitchen. However, remember that the fruit will be tastier if left to ripen on the vine!
Know your tomatoes: What are the different kinds of tomatoes?
There’s a huge range of tomato varieties to choose from, each with different sizes, colours and tastes. The time taken to fruit will depend on the type of tomato plant you choose, for example, small varieties are the easiest and fastest to grow. As well as this, each kind of tomato plant will have different pruning and support needs. There are 3 main kinds of tomato plant: cordon/ indeterminate, semi-determinate, and bush/ determinate.
The most common are cordon tomato plants, which are single stemmed and grow very tall. Semi-determinate plants are like cordon but grow shorter. As these plants grow, you’ll need to tie them to a support and pinch out their side shoots (the stems growing between the main stem and a leaf branch).
Determinate tomato plants are often known as bush or dwarf types as they stop growing sooner. These are the types most suited for hanging baskets. For beginner gardeners, or those looking for the easiest way to grow tomatoes, you’ll find the bushy varieties require less maintenance and care. They don’t need pruned or trained. As they grow, they’ll sprawl along the ground or trail out of a pot.
Here are our favourite varieties of tomatoes to grow at home:
Tomato ‘Moneymaker’
The ‘Moneymaker’ is a traditional choice and is loved for its reliability and remarkable flavour. It’s a medium sized tomato that grows well both in a greenhouse or in the garden.
Tomato ‘Tumbling Tom Red’
deal for hanging baskets and containers, ‘Tumbling Tom Red’ is a compact bush variety that produces a non-stop supply of cherry tomatoes for the whole family.
Tomato ‘Beefmaster’
This is a classic beefsteak tomato that produces huge fruits, which are perfect for salads and succulent burgers. For best results, you should grow these in a greenhouse.
How to care for tomato plants
While tomato plants are relatively easy to grow in the garden, it’s still important to look after them well if you want them to develop plump, juicy tomatoes. Tomato plants need as much light, warmth and shelter as possible. Here are some of our top care tips:
How much water do tomatoes need?
Tomatoes need a lot of water, especially in containers. Water little and often; once per week or twice in hotter weather, never letting the soil dry out completely. Keep the foliage dry by watering the soil around the plants instead of directly on top of the plants.
When should I fertilise my tomatoes?
Tomatoes have a reputation of being hungry plants! Once your tomatoes are beginning to flower, add Levington Tomorite tomato food into your watering can mixture. This will help produce a delicious and bountiful crop.
How to prune tomato plants
Pruning tomato plants helps divert their energy into producing more fruit. Remove the side shoots on cordon and semi-determinate varieties as they grow. Once a plant has 6 flowering trusses, cut off the tip of the main stem 2 leaves above the top flowering truss. You don't need to prune short bushy tomato plants.
How to protect tomatoes from pests and diseases
As well as removing any diseased leaves from your tomato plants, you should regularly check them for bugs or eggs. Planting your tomatoes near basil or marigolds is a natural way to deter pests. This is known as companion planting, a practice where you grow different plants like flowers and herbs close to each other for mutual benefit. Often, the scent of the plant confuses the pests and lure them away from your crops. Most combination plants also attract pollinators like birds and bees to your garden, which are important in the plant reproduction and growth process. They also attract other insects like ladybirds, which pray on aphids (a common bug which infects plants). It's been an age-old gardening tradition for years and a fantastic and natural way to not only control pests in your garden, but also to maximise your space. It gives your garden an elevated aesthetic, adding some colour and life to fruit and veg patches.
While we love the strong smell of French marigolds, whiteflies certainly don’t! Planting these flowers beside your tomato plants, especially in a greenhouse, helps keep these pests away. Sow flower seeds or plant young plug plants in your tomato containers or as a row in your bed in front of your tomatoes.
Cleaning pruners and tools between uses will also help prevent diseases spreading to your plants.
How to train tomato plants
Depending on which variety you're growing, tomato vines will need trained. Tie tall stems to plant support sticks or bamboo canes so they grow upright. Bushy varieties may also benefit from a shorter stake placed in the middle to help keep fruit off the ground it grows.
Now you know everything there is to know about planting, growing, caring for and harvesting tomatoes, it’s time to give it a go yourself! Whether this is your first spring growing your own or your tenth, it’s a wonderful way to make full use of your outdoor space, no matter how big or small. Before you know it, you’ll be biting into your own homegrown tomatoes or enjoying their tangy, sweet taste in all your favourite summer dishes. Find everything you need to get started in-store and online at Dobbies today.