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How to grow tomatoes

Tomatoes are one of the easiest crops to grow at home, and the fruits taste richer and sweeter than any that you’ll find at the supermarket. Haynes shows you how to succeed with a mouth-watering harvest – and if you want to become an expert, try the Haynes Home-Grown Vegetable Manual.

What tomato plants should I buy? 

Garden centres are packed with young tomato plants from March to May. You’ll find all the tried and tested favourites such as ‘Moneymaker,’ ‘Alicante,’ ‘Gardener’s Delight’ and ‘Ailsa Craig’.

First, decide if you want to grow standard, cherry or beefsteak tomatoes. Independent garden centres often have a wider choice of plants.

What are grafted or turbo tomato plants?

Grafted plants have lots more vigour and can crop earlier, but generally cost more. Grafting means that the upper part of the young plant (scion) has been joined to a vigorous rootstock of another variety.

If that sounds a little complicated, don’t worry. It’s like having a car with a turbocharger – quicker off the mark and plenty of power, except that with ‘turbo’ plants, you’ll end up with a heavy, earlier crop of tomatoes, and not a speeding ticket.

Where do I grow tomatoes? 

Like Brits abroad, tomatoes love to bask in heat all day long, so choose the brightest part of your garden, or ideally, a greenhouse in full sun.

If growing under glass, you’ll need to paint shading onto the glass by May – it won’t cut down light levels, but it’ll prevent your plants and crops from scorching in the summer sun.

Coolglass, made by SBM Life Science, is easy to apply to glass with a paintbrush and will stay on all summer. It can be wiped off with a household duster in autumn.

When can I put the plants outdoors? 

Not until after the last frosts, which can mean late May in the south or early June in the North. Keep a close eye on the weather forecast.

What do I grow tomato plants in?                                               

Growing bags are easiest, but don’t try to cram more than three plants into one bag. Avoid thin, cheap bags which offer little space for roots to develop and don’t hold much water.

It’s always worth tracking down extra fat growing bags, such as the Levington Tomorite Giant Planter or Gro-Sure Tomato Planter.

Or use big plastic pots, but make sure they have plenty of drainage. Fill with multi-purpose or John Innes No 2 compost before planting one tomato plant per pot.

How often should I water tomatoes? 

Tomatoes are thirstier than a pub full of drinkers during happy hour, so make sure you have a hosepipe or water butt nearby. In high summer, greenhouse tomatoes will need watering daily – and often twice a day.

Allowing plants to dry out between waterings leads to problems such as split fruit and blossom end rot. Standing pots in big saucers to catch water run-off can help to reduce the risk of compost drying out.

Do I need to feed tomatoes?

Yes – regularly, once the first truss of fruit has set (that’s when the small yellow flowers drop to reveal tiny tomatoes). Follow the instructions on your bottle of tomato food, but it’s likely to be weekly outdoors, and up to twice a week under glass.

Never be tempted to bung in a bit of extra food for good measure when diluting the feed into a watering can, because this can damage your plants.

There are loads of brands of tomato food, such as Westland’s Big Tom, and Scotts’ Levington Tomorite.



Why do side shoots need pinching out? 

Most common varieties are grown as cordons – which means a single stem that’s trained and supported by a cane or wire. Check your variety. If it’s a cordon, pinch-out side shoots that appear where leaves join the stems.

This is because you want plants to put all their energy into producing tomatoes, not lots of foliage. Yellowing leaves at the base of plants can be removed as they mature, but don’t overdo it and strip plants bare.

Outdoors, pinch off the tops of plants when they reach the tops of their canes or supports. Do the same in greenhouses when plants hit the roof. If yours is a ‘bush’ variety, leave the sideshoots untouched.

What is tomato blight? 

Tomato blight is, to put it bluntly, a disaster when it strikes. Healthy plants can be reduced to a decaying, collapsing mess in a matter of days. The airborne disease is worst during warm, wet, humid summers.

Plants under glass are at less risk, but are not immune. If plants and fruits rapidly turn brown, shrivel and die, it’s game over – bin or burn the lot.

If growing outdoors, it’s worth tracking down blight-resistant tomatoes: try Suttons’ ‘Crimson Cherry’ or ‘Crimson Crush’. Thompson & Morgan’s tomato ‘Mountain Magic’ is claimed to have good blight resistance, too.

Can I grow tomatoes if I don’t have a garden?

If you only have room for a hanging basket or window box, there’s a tomato plant to suit. Tomato ‘Tumbling Tom Red,’ ‘Hundreds & Thousands’ and ‘Romello’ are perfect for baskets or pots.

These are known as compact bush varieties, and you won’t need to support stems or remove side shoots.

How do I harvest tomatoes?

When crops are ripe and coloured all round, it’s time to pick. Hold the tomato and break it away at the swelling on the stalk. Don’t yank the fruit or you risk snapping off the entire truss and any unripe toms!

What do I do with the plants when they finish cropping?

When you’ve picked all your tomatoes, usually by late September or early October, cut the plants down and put them in the compost bin (or green waste bin). Tomato plants don’t over-winter, so there’s no point keeping them.