How to grow Tomatoes

How to grow Tomatoes from seed

When growing tomatoes outside, remember that they thrive in a sheltered, sunny position. There’s no single best way to grow tomatoes: all varieties can be grown under the cover of a greenhouse or polytunnel, but many are also suitable for outdoor cultivation, so long as these growing requirements are met. Look out for those varieties described as suitable for outdoor growing, or pick an old, reliable favourite such as ‘Shirley’ or the appropriately named ‘Outdoor Girl’. 

If you’re growing tomato plants in the soil outside, pick a spot where tomatoes or potatoes have not been sited within the past two years. This will reduce the chances of crop-specific pests and diseases, such as late blight, passing on to the new crop. 

Prepare the soil by digging it over and incorporating plenty of well-rotted organic matter such as home-made compost. Tomatoes perform best when given a nutrient-rich soil, so early preparations will go a long way to ensuring the best possible yields. Rake the soil level a week before planting, ready for your new occupants.

Growing tomatoes in a greenhouse

Greenhouse-grown tomatoes will stand the best chance of success if they are introduced into a clean, sterile environment that’s free from overwintering pests, so thoroughly clean all nooks and crannies within your greenhouse the winter before. 

Growing tomatoes in a greenhouse will allow an earlier start and will extend the season, meaning you’ll be left with more fruit. Plants can be grown in greenhouse beds, or you can plant tomatoes in grow bags or pots.

Sowing tomato plants

Tomato plants are ready to move into their final positions approximately seven to eight weeks after sowing. So, work back from the usual date of your last frost – the end of May in the Midlands – and sow accordingly. This means sowing from the start of April for outdoor plants. Sowings can be made even earlier, in March or late February, if you’re growing tomatoes indoors in the greenhouse, or in milder parts of the southwest.

Sow your tomato seeds into 7cm pots of seed compost or potting soil/potting mix. Fill the pots up to within 1cm of the rim, and gently pat the surface down. Water the pots thoroughly and allow them to drain, before spacing individual seeds at least 2cm apart. 

Cover the seeds with a 0.5cm layer of sieved seed compost or vermiculite, and lightly water them in using a watering can fitted with a fine rose. Move the pots to a propagator or tomato grow house to germinate, or place a clear polythene bag over the tops of individual pots, held away from the compost with sticks, and secured in place using an elastic band. 

Growing tomato seedlings indoors

For those of you asking ‘how long does it take for tomatoes to grow?’... it doesn’t take long at all! They will germinate quickly at a temperature of around 20°C, so if you’re growing indoors, tomato seedlings will start to grow on the top of a warm indoor windowsill, for example. Similarly, a snug, warm airing cupboard can be a good environment, but check the pots daily for signs of growth, and remove them as soon as germination occurs.

It doesn’t take long for tomatoes to grow: seedlings should break free of the compost surface within 10 days – often sooner. At this stage, they should be removed from the propagator and placed in a bright position indoors. Only water the seedlings once the compost begins to dry – they will be fine for the first week or so.

Pricking out Tomatoes

When the first adult leaves on your tomato plants are just visible, it’s time to prick out your seedlings into separate 7cm pots. Fill the pots with multipurpose compost, firm it in gently, water well and leave overnight in the growing area to raise the compost temperature – this deters damping off disease. 

Very carefully tease out the tomato seedlings from their germination pot – sliding the seed compost out of the pot to get at the young seedlings is the easiest way of doing this, and will leave roots intact. Dibble holes into the new pots using a pencil, and, holding each seedling by its leaves, lower the roots into the hole before feeding back with compost.

Grow the tomato seedlings on a sunny window sill or in the greenhouse, taking care to avoid any draughts and cold nights. If roots appear at the base of the pot before it is time to plant them out, then pot them on again into a 12cm pot. 

The young plants can go outside as soon as the danger of frost has passed – at this point they should be about 15cm tall. Begin hardening off the tomato plants a week or two beforehand by leaving them outside in their new positions during the day, and bringing them back under cover at night.

Transplanting your tomato plants

To plant tomatoes outside or within the greenhouse border, dig a hole larger than the rootball. Remove the plants from their pots and then place them into the holes, feeding back the soil around the roots and firming in gently. Water the plants in well and position a sturdy, strong bamboo cane or pole next to each one. Space your tomatoes at least 45cm apart so that they have plenty of room, and so that fresh air can circulate around them. 

You can grow tomatoes in pots in the UK, so long as these are at least 23cm across. Grow bags are also a hugely popular and straightforward way of cultivating them. If you’re growing tomatoes in grow bags, plant as instructed, but be sure to break up any clods of compost before cutting out your planting holes in the top of the bag and drainage slits in the bottom. 

Choose a generously proportioned grow bag – the extra money it costs will be paid back many times over by the number of fruits you’ll pick.

Caring for your Tomatoes plants + problems

As soon as the first flower trusses appear, begin feeding plants regularly using an organic liquid tomato feed that is high in potash to encourage further flowering and fruiting. Allow up to six trusses to form on greenhouse cordon tomatoes, or four on outdoor tomatoes; as soon as this number is reached, pinch out the tops of plants. 

Tie in cordon tomatoes as they grow onto their supports, and pinch out any side shoots that form where leaf stalks join the main stem. If side shoots are left to grow, they will form a new branch, drawing energy away from fruit formation.

Bush types of tomato form flowers and fruits at the end of each branch, so they don’t require any tying in or removal of side shoots. This makes them an attractive choice for time-poor gardeners! Some support can be given, though, to prevent plants from sagging under the weight of their fruits.

Read our complete guide to pinching out tomatoes for even more tips and advice.

Varieties of Tomatoes

Tomatoes originated from a warm area of South America before they were introduced to southern Europe. Few crops have been developed over the years to give such a range of habits, flavours and colours as these delicious, exotic fruits. There are literally hundreds of different varieties of tomato to try, giving rise to many devotees to this well-travelled fruiting plant.

If you’re wondering which varieties are the best tomatoes to grow, it really depends on what you fancy. As well as standard red toms, you can sink your teeth into yellow, striped, near-black and cream-coloured ones. You’ll find that biting into a delicious homegrown tom is a million miles away from eating supermarket tomatoes, which are bred for shelf-life and uniformity rather than flavour.

F1 hybrid tomato seeds promise outstanding performance, often combining vigour, taste and disease resistance to give trouble-free crops. But it’s also worth seeking out the older heirloom varieties, which will let you enjoy many old favourites that you wouldn’t run into in the shops.

Tomatoes varieties to try