How to grow tomatoes

No summer salad is complete without a juicy home-grown tomato picked fresh from the vine. These health-promoting fruits are relatively easy to grow if you get your planting time right and feed correctly. Expect to pick your first ripe fruits from the end of July through until October. 

Check out our video tutorials on how to grow tomatoes on our YouTube channel here.

Growing Tomatoes: Soil & Growing Position

A rich soil improved with organic matter and some fertiliser is ideal for growing healthy tomatoes, especially if it is a warm sunny spot in front of a south-facing wall or fence.

Alternatively, you can grow tomatoes in a compost planter pack positioned on a sunny patio or balcony. Gardeners can get great results from specific tomato planters because the compost is carefully blended and enriched with nutrients to encourage strong early growth ready for maximum cropping and tasty tomatoes.

When To Plant Tomatoes

Tomatoes are warm-weather plants, meaning that your plants will struggle in particularly cold temperatures. So you will need to sow your tomato seeds indoors in trays of fine compost. Ideally, you will be looking to plant outside when the night time temperature is consistently above 10 Degrees Celsius.

Sow your seeds in April and you will have seedling plants ready for planting outside at the end of May or beginning of June. This will be when the soil temperature is warm enough (around 15 Degrees Celcius +) for planting.

To test this out without a thermometer, try thrusting a finger into the soil and keeping it there for around a minute. If you cannot keep your finger in the soil for a whole minute without feeling uncomfortable, then the soil is ready.

Alternatively, wait until May and buy ready grown seedling plants from your local garden centre.

Types Of Tomato Seeds & Plants

There are three different types of tomatoes to choose from. ‘Cordon’ varieties are grown as a single stem that needs support and the side shoots regularly removed. ‘Bush’ varieties need no training, support or stopping. ‘Trailing’ types don’t need support or training and are good for tumbling from patio pots and hanging baskets.

Cordon varieties include: ‘Gardeners Delight’ (small), ‘Sungold’ (small), ‘Cherry Belle’ (small), ‘Alicante’ (medium), ‘Ailsa Craig’ (medium) and ‘Dombito’ (large).

Bush varieties include: ‘Glacier’ (medium), ‘Roma’ (plum) and ‘Marmande’ (large).

Trailing varieties include: ‘Garden Pearl’ (small), ‘Tumbling Tom Red’ (small) and ‘Tumbling Tom Yellow’ (small).

Buying & Sowing Tomato Seeds/plants

Sow your tomato seeds in individual cells of fine compost in early April. Plant up tiny seedlings when two true leaves are showing, one plant to a 5cm pot of enriched compost. Alternatively, buy ready-grown plants from your local garden centre at the end of May.

Plant out all plants early in June or end of May if night temperatures are warm. Plant into garden soil 60cm apart or 3 to each compost planter as soon as frosts have finished. Tumbling varieties do well in patio pots or hanging baskets filled with a moisture-controlling compost.

Pricking Out Tomato Plants

When pricking out small tomato plants aim to use a 3-inch pot (for young seedlings). A multi-purpose compost or a specific fruit and vegetable compost will work well. First, place a small handful of compost into the bottom of the pot then lift and place the tomato plant – using the leaves, not the stem - from the seed tray into the centre of the pot. Still holding the plant by its leaves, place compost around the plant up to the base of its first leaves.

Next, using a finger and thumb push the compost down to hold the plant in place. Fill with remaining compost up to the brim of the pot.

How To Plant Up Tomatoes In Grow Bags

Cut out large holes in the top of your grow bag – large enough to fit as many tomato plants as you wish to plant. Either remove the plant from the pot or insert the pot directly into the compost.
Remember to use canes or string to help support the growth of the tomato plant upwards to avoid any sagging or drooping of the plant once it begins to produce fruit.

How To Plant Up Tomatoes In Pots & Containers

Take your pot or container (ensure there is sufficient drainage capacity) and place your tomato plant on top of your hanging string. Add 2 inches of multi-purpose compost around the plant and firm with your fingers around the root bowl. At 3 week intervals add another 1-2 inches of compost until the pot or container is full. This method allows the roots to spread and develop giving a more vigorous, healthy plant. Water in the compost at each interval.

How To Plant Up Tomatoes In Hanging Baskets

Take your hanging basket and place an insert inside to hold the compost and plants in place. For hanging baskets, tumbler tomato plants work best as they cascade over the edges and provide smaller (30mm diameter) tomato fruit.

Fill the basket 3/4 with multi-purpose compost and place a few tomato plants near the edges slightly tilted towards the edge. Tap down compost to remove as many air cavities as possible and then fill compost to the brim. Water in and you are ready to go.”

Cordons: Stake each cordon plant and tie the tomato stem loosely to the stake at 30cm (12in) intervals. Pinch out side shoots that develop where leaves join the main stem. After 4 or 5 trusses have formed, remove the growing tip of the main stem, so the plant concentrates all its energy on developing the fruits to ripeness.

Trailing: When grown in containers regular watering is the key to success. Try to keep the compost moist but not soaking wet.

All types: Start feeding all plants with liquid tomato plant food after the first truss has set fruit and repeat at 14-day intervals.

A Guide To Watering Tomato Plants

How to grow tomatoes

There are two popular methods for watering newly sown tomato plants.
1. Dipping: Take the tomato plant tray and dip in a container of 1cm deep water. This method allows for the compost to soak up the moisture and doesn’t disturb the sown seed (which conventional watering can sometimes do).
2. Watering Can: Apply a rose to the end of your watering can (upwards facing is best) and gently glide the water over the tomato plant tray. Repeat a few times.
After watering, cover the trays with polythene or newspaper for up to a week until germination occurs. Once the seedlings appear to take the cover off and leave in a warm, dry and sunny spot.

Pests, Diseases & Problems

  • Whitefly is the most serious pest problem of tomatoes. If your plants are attacked spray them with a suitable insecticide and spray every 10 days or as directed on the product.
  • Blight is the most serious disease. Luckily, it is possible to accurately predict when blight outbreaks are going to happen. Sign up for the free Blightwatch service to get e-mail alerts when blight is forecast in your area.
  • Blossom end rot is a common problem of tomatoes, which is caused by irregular watering or dryness at the roots.
  • Tomato leaf mould is a common fungal disease of tomatoes growing undercover, in a greenhouse. It is rarely seen on outdoor plants. Once it becomes established, it can spread rapidly and cause significant losses.

Top Tips For Growing Tomatoes

Some top tips for growing tomatoes:
1. Watering: Be careful not to over-water or under-water a tomato plant. Over-watering can cause root death and nutrient deficiency. Underwatering can cause blossom end rot. Always relate watering to the size of the tomato plant, if the leaves/fruit look healthy and the weather conditions.”
2. Pollination: Pollinating a tomato plant is important to ensure healthy tomato growth. Ensure there is plenty of light and humidity where the plant is growing as this encourages the development of pollen. Also, every so often tap the trusses or canes holding the plant up to let pollen move around.
3. Pests: Two of the most common pests for a tomato plant is whitefly and red spider mite. These can be tackled using a good on contact and systemic bug killer. Another pest to tomato plants is slugs and snails, which if not dealt with will eat ripening tomatoes. Use a slug repellent sprinkled around the plant. (organic varieties also exist)
4. Feeding: Feeding a tomato plant is important to provide nutrients – in particular potassium, phosphorous & nitrogen – that allow healthy, strong fruits to develop. A great tomato plant food is ideal to help with growth.

If you begin to see yellowing of the leaves it may be an indication of magnesium deficiency in the compost. Mix about 2 ounces of magnesium sulphate salts in a gallon of water and water in around the plant.

Growing Tomatoes: Frequently Asked Questions

We have answered some frequently asked questions regarding getting started growing tomatoes. Including:

  • Where is the best place to grow tomatoes?

The best place to grow tomatoes is in a greenhouse, conservatory or polythene tunnel, if possible. Just ensure it is a spot with plenty of sunshine.

  • Can I grow tomatoes outside in the garden?

You can but it has to be late in the tomato growing season to avoid the possibility of frost damage. Late May is usually the best time but is subject to weather conditions.

  • What medium should I use to grow my tomatoes?

Soil and compost is the best medium but if plagued by pests and diseases consider moving to grow-bags or containers.

  • What are the minimum and maximum temperatures for growing tomatoes?

In a greenhouse, temperatures should not drop below 14° at night and should not exceed 21° during the day.

  • How many trusses can I expect from a tomato plant?

You should expect a minimum of 6 trusses but it could rise to 7 or 8 trusses depending on when planted.

  • What varieties of tomatoes can I grow from seed?

Any and all varieties can be grown in the UK including cherry, beef, plum, alicante and moneymaker. Expect cherry tomatoes to fruit first.

  • When should I sow?

As early as mid-February but usually in March and April, depending on weather conditions.

  • Do I have to grow from seed?

No, you can buy young plants or semi-grown plants.

  • How do I plant out my tomatoes?

Plant tomato seedlings 18 inches apart. Planting closer may be possible but only for very sunny spots.

  • What is the best way to support tomato plants?

You can use canes or hanging string.

  • Are grow bags good for growing tomatoes?

Grow-bags are ideal as they contain the right amount of soil nutrients. It should be possible to fit three plants in one large grow-sack.

How to grow tomatoes
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