How to Grow Tomatoes in Your Garden

By   | Last Updated :   March 19, 2021 | Filed In :   Growing Guides

Tomatoes are great for all kinds of recipes, from rich sauces and hearty soups, to fresh salads and delicious breakfasts. If you’re planning to start growing your own vegetables, tomatoes are one of the best places to start, as they’re easy to look after and produce lots of fruit from just a few plants. Let’s take a look at how to grow tomatoes in your own garden.

Growing Tomatoes: Getting Started

how to grow tomatoes in pots on a windowsill

Tomatoes are grown from starter seedlings, known as ‘slips’. Slips are available in all kinds of tomato varieties, from tiny cherry and plum tomatoes, to bigger salad tomatoes and fruity beefsteak tomatoes. You can create the slips yourself from seeds, but they’ll need to be kept indoors during the first stage of growth.

Tomatoes grow in two ways: bush tomatoes, which grow in a short, shrub-like shape, and cordon tomatoes, which reach upwards and will need supporting with stakes. If you plan to try growing your tomatoes from seeds, the seed packets will tell you what kind of variety they are.

In this brief guide, we’ll show you how to grow tomatoes from seeds as well as slips. All types of tomatoes will need nutrient-rich soil and lots and lots of sunshine for the best yields.

Sow in: February, March, April

Move outdoors in: May, June

Harvest in: July, August, September

How to grow tomatoes: Prepare the soil

Before doing anything else, it’s important to prepare the right kind of soil for your tomatoes. To get the best crops, you’ll need nutrient-rich compost, ideally well-mixed with dried manure to keep the soil texture light. Tomatoes will need about 20cm of soil, so choose your containers or garden vegetable patch accordingly.

Sowing tomatoes

how to grow tomatoes in seedling trays before planting them outdoors

Tomatoes need the warmest possible conditions to thrive. If you plan to grow your tomato plants outside, start your seedlings indoors in late March or April to have the weather by the time they’re ready to move outdoors. For tomatoes that will be kept in a greenhouse or on a sunny kitchen windowsill, you can start the seedlings in February or early March.

Plant your tomato seeds in propagation trays filled with potting compost, cover them with a clear lid or plastic sheet, and position them in a spot with full sun exposure. You’ll know when a seedling is ready to be moved into a larger (9cm) pot once it has two, fully-formed leaves – but still keep them indoors for now!

Hardening off tomatoes

Once your seedlings – or your shop-bought slips – are about 15cm tall, you can start preparing them to be moved outside, or into a greenhouse. This is done in a gradual process known as “hardening off”. Hardening off helps plants adjust to fluctuating temperatures, direct sunlight, greater moisture loss and getting blown around in the wind.

Over the course of 1-2 weeks, take your seedlings outside for gradually increasing lengths of time – starting with just a couple of hours, moving slowly to the entire day and, eventually, overnight. You can use a greenhouse/cold frame or cloche to provide a bit more protection during the process.

Planting tomatoes

tomatoes and lettuce in a raised planter

When the weather is consistently above 10°C, and as soon as your tomatoes are acclimated to being outside, you can plant them in the soil. By this point, some of your seedlings may even be flowering – it’s okay, don’t rush!

Choose a sunny and reasonably sheltered area, and plant your seedlings about 8cm deep into the soil, roughly 50cm apart from each other. You can also plant them in grow-bags, containers, or even hanging baskets for bush varieties.

Cover the roots and give them a sprinkle of water. A layer of mulch is optional. At this point, give cordon tomatoes a chicken-wire cage or wooden stake for support as it grows. As the stems grow, string them into place or weave them through the wire.

Growing tomatoes

close-up of tomatoes tied to a stake

Bush tomatoes are fairly easy to look after as they grow, and won’t need any special care. Cordon tomatoes need a little bit more attention!

In addition to staking, cordon tomato plants will benefit from having side-shoots trimmed back (the ones that appear between the main stem and the leaves on each arm). When your outdoor plants have grown to accommodate 4-5 trusses (branches), you should pinch off the top to prevent them growing any more. This is because it’s unlikely the fruit on these higher trusses will have a chance to ripen before the plant dies in late Autumn, so it instead focuses the plant’s energy towards the fruit on the lower branches, making them bigger and more delicious. For indoor or greenhouse plants, you can let them grow up to 7 trusses.

For both bush and cordon tomatoes, keep the moisture levels consistent to prevent the fruits from splitting, and top them up with liquid fertiliser every two weeks. When you notice the first fruits, swap to a potash feed.

Harvesting tomatoes

As your tomatoes begin to reach the right size for the variety you’ve chosen, watch out for signs of ripening. Tomatoes are ready when they’ve got a consistent colouring (usually red, but sometimes orange or yellow, depending on the variety). If you gently squeeze them, they should be firm, but with the slightest hint of give.

Pinch ripe tomatoes off individually, and leave the younger ones to continue to grow.

Wondering how to grow tomatoes at the end of the season? If your plants still have tomatoes that aren’t quite ready as the cold begins to set in, you have a couple of options. Container plants can be brought inside, and outdoor plants can be covered with a cloche to give them a little bit more time. You can also pick unripe tomatoes and store them somewhere warm and dark (some people also put a banana nearby) to push them a little bit further along. Even if your tomatoes are still a little bit green, this trick should work.

tomatoes are great crops to grow in containers

Common Problems With Tomatoes

As with any plant, there are a whole host of problems that can occur in tomatoes, some of which will spoil the fruit and make it completely inedible. When you’re figuring out how to grow tomatoes, these are the most common issues that you’ll want to look out for.

  1. Insufficient potassium will lead to uneven ripening and result in your tomatoes losing all of their zingy flavour. Keep your plants topped up with a high potash feed – look for tomato-specific types, and follow the instructions closely.
  2. Splitting, cracking or ‘russeting’ tomatoes are a sign that your tomatoes are struggling with fluctuating temperatures and/or moisture. Unfortunately, there’s not always much you can do about the weather that causes it! Minor patches on your tomato skins are fine, but if the fruit splits open it’s going to make the plant susceptible to rot.
  3. If you notice that the base of your tomatoes are brown and soft, you’re probably contending with blossom-end rot. This occurs when the fruits are struggling to get calcium, but can be caused by the wrong proportions of other nutrients. The best solution is to remove the damaged tomatoes (they’re not going to taste right anyway), make sure you’re keeping the soil evenly moist, and keeping greenhouse/indoor plants ventilated.
  4. A magnesium deficiency will town older leaves yellow, threatening the health of the overall plant. It’s usually caused by low magnesium levels in the soil, the stress from heavy fruit, or from roots that have been damaged by too much water or fertiliser. Make sure your liquid feed has magnesium in, and consider getting your soil tested to see how deficient it is. A high-magnesium solution might be required.
  5. Iron deficiency will cause younger leaves to turn yellow and limp. Similar to a magnesium deficiency; you’ll need to determine the underlying cause and treat it with an iron-rich feed to solve the problem.

Tomatoes can be a little more finicky than root vegetables like potatoes, but it’s incredibly satisfying to watch the literal fruits of your labours ripen on the vine, in front of your eyes. Hopefully this guide will have shown you how to grow tomatoes with a little bit of confidence, and you’ll be whipping up delicious home-grown recipes in no time!

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By Kirsteen Mackay

Kirsteen is a professional writer who traded a tiny garden for an even smaller balcony when she moved to Brighton in 2015. Her interest in gardening stems from a keen desire to turn her simple slab of concrete into a lush urban oasis, complete with cosy-but-practical garden furniture and delicious edible plants.

View All Posts By Kirsteen Mackay »

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