How to grow tomato plants

Which variety of tomato should I grow?

From fun-sized cherry tomatoes for pizzas and salads to stonking big beefsteak tomatoes for burgers and bruschetta, tomatoes come in thousands of different shapes, sizes and colours.

As with any homegrown produce, it’s always a good idea to get varieties that you’re likely to eat – so whatever size of tomato you’re after, you’re pretty spoilt for choice.

Tomato plants are split into two categories: determinate and indeterminate.

Determinate tomato plants

Determinate tomato plants are also known as ‘bush tomatoes’. These are small and compact plants which will grow to a certain height (usually around 90-100cm depending on the variety) and produce their flowers and fruits from side shoots. Their fruits are generally all ready for picking within a small window of a couple of weeks before it stops producing.

Determinate tomato varieties are fantastic for smaller gardens, or gardeners who don’t have the time (or patience!) for too much aftercare. They also lend themselves very well to growing in pots and planters.

Indeterminate tomato plants

These are the skyscrapers of the tomato world, and will happily grow up and up until they’re pinched off – you’ll also see them referred to as ‘vining tomatoes’. They require a little more aftercare, but the reward is a longer growing period compared to bush tomatoes.

Indeterminate tomato plants can be grown in pots or in the ground, as long as you give them some support.

Top tip: if you’re really pressed for space, dwarf tomato varieties are also available.

When to plant tomato seeds

You can start your tomato plants indoors from seed in early spring, as early as six or eight weeks before your last frost date. Depending on where you are, this ranges from February to April.

How to grow tomatoes from seed

It’s tomato time.

Fill your seed tray with a good quality potting mix and pop your seeds on the surface of the soil. Depending on the size of your seed tray, you may be able to fit 2-3 seeds into each plug – just make sure they’re about an inch apart.

Sprinkle a thin layer of potting mix over the top to cover, and give them a light watering to get them started.

Pop your seed tray into a propagator if you have one, and place it on a warm windowsill in your home. Don’t worry if you haven’t got a propagator – loosely cover the top of your seed tray with cling film or a plastic bag to retain moisture, until you see the seeds start sprouting. This normally takes a couple of weeks depending on conditions, and whether you talk to them or not.

Potting up tomato plants

Tomato seedlings are ready to transplant into their own pots when they’re an inch or two tall, when they have grown their first ‘true’ leaves. These are the ones that grow after the first leaves that appear when they first sprout from their seed casing.

Carefully lever the seedlings out of their tray, holding them by the leaves, and pop them into their own small pot filled with potting mix, submerging some of the stem within the soil. Put the pot back on a sunny windowsill until they’re ready to be planted in their final position in about a month.

If your tomato plants are over-achievers and start to grow too big for their pot before your last frost date, simply pot them up into a slightly larger pot.

Top tip: don’t be tempted to plant your seedlings into a pot that’s too big, or there’ll be too much soil for the roots to deal with, leading to soggy soil and potential root rot. This isn’t fun for you or the tomatoes.

Planting tomato plants outside

The time to plant tomatoes outdoors is in early summer, when the temperature has reached around 16 degrees Celsius, which usually falls in the month of May for most parts of the UK.

It’s a good idea to start ‘hardening off’ your plants first; popping their pots outside during the day and bringing them back in at night. This gets them used to being outside, so it isn’t too much of a shock!

Tomatoes love warmth, so find them a sunny spot once they’re ready to plant. They’ll need well-drained soil that’s enriched with plenty of organic compost, whether they’re going in the ground or in pots.

Top tip: dig your tomato plants in fairly deep – up to the first set of leaves. Tomato plants can create roots from anywhere on their stems, so the more roots they can put out, the more likely you are to get strong plants and plenty of tasty fruits!

Top tips for tomato plant aftercare

All tomato plants like moist soil, so make sure you keep them topped up, especially in the warmer months. Avoid watering when the sun is at its strongest, though – it’s best to give the soil a good soaking in the early morning or evening.

Make sure to water your tomato plants regularly, or your fruits are likely to split when they ripen!

When watering, focus your watering can around the base of the plant and avoid water splashing onto the leaves, as it’s more likely to spread airborne diseases.

With indeterminate vining tomatoes, you’ll need to stake them up when they reach a certain height using plant canes, or they’ll fall over! Remove any side shoots that start to appear. These are shoots the grow between the stem of the plant and main branches. Simply pinch them between your fingers – this focusses the tomato plant’s energy into creating flowers, and then fruit!

When flowers do appear (yay!), start using a tomato feed or seaweed fertiliser once a week or so to give them a boost in nutrients.

It’s time to harvest!

If everything goes to plan, your flowers should turn into tomatoes any time from June onwards, depending on the weather!

Make sure the tomatoes are getting plenty of light, and keep on top of your watering and fertilising. Simply pick or snip off your tomatoes when they’re fully ripe and store them at room temperature for up to a week.

For the best-tasting tomatoes, fresher is better. Treat yourself to a tomato straight from the vine as you’re picking them – you’ve put in a lot of work, and it’s one of life’s pleasures, so enjoy it!

Companion planting for tomato plants

Like most things in your garden, your tomato plants need pollination to produce fruits, so it’s well worth including some companion plant alongside your tomatoes.

A popular flower for this is marigolds, as they’ll attract beneficial bugs such as bees, as well as pest predators like hoverflies and ladybirds. Not only will this make sure your plants get the pollination they need, but it’ll also reduce the likelihood of pests like aphids and whitefly – and they look lovely too, of course!

Basil is also a worthwhile companion to tomato plants. It’s said that their scent repels flies and another annoying bugs, and they’ll also take one for the team by luring whitefly away from your tomato plants. That’s what being a good friend is all about.

Common problems and solutions

Blight

Blight is a fungal disease, and it’s a nasty little so-and-so. It’s more likely to happen if you have a particularly wet summer, and is characterised by a browning of the stems, leaves, and fruits of your tomato plant.

Annoyingly, there’s not a huge amount you can do, unless you catch it early. If your tomatoes are in pots, move any unaffected plants well away and hope for the best.

Discard any fruits that have brown patches, and salvage the rest. Green tomatoes can be used to make green tomato chutney, or sliced and fried for a tasty snack.

Tomatoes which are semi-ripe can be stored at room temperature. If they’re with other ripe tomatoes, they may ripen up on their own.

Top tip: putting a banana next to your ripening tomatoes can help them ripen faster. Science!

Blossom end rot

Sounds a bit dramatic, doesn’t it? If your fruits are discoloured at their base, you may have blossom end rot.

This is often caused by irregular watering. If the soil dries out and is then hit with a lot of water, the fruits can split which leads to this pesky disease. Keep your tomatoes consistently well-watered, especially on warm days.