How to Grow Tomatoes in the Greenhouse

Tomatoes are a hugely popular fruit that can commonly be found in greenhouses across the UK throughout the summer months. Whilst some gardeners prefer to grow their tomatoes outside, for others it is much easier to ensure they have fruit from June through to October by growing tomatoes indoors in a greenhouse or grow house.

Tomatoes are not the easiest of plants to grow and they require quite a lot of care and attention throughout the growth cycle during the summer months. They are also susceptible to a large variety of diseases and pests which can put some home growers off. When and where to plant and grow tomatoes will depend entirely upon the type of tomatoes you wish to grow and the conditions within which you wish to grow them.

Typically, tomato plants suitable for growth in a greenhouse are Cordon varieties. These single stemmed plants can reach heights of up to 6ft if not controlled. Some of the most common varieties include the Ailsa Craig, Alicante or Moneymaker but there are loads of other varieties to sample.

When to plant tomatoes?

In aheated greenhouse, tomato seeds are sown in late December and planted out in late February or early March for a May-June crop. However, if you are using a cold or unheated greenhouse, like most gardeners across the UK you should sow the seeds in early March and plant out in late April or early May. The first fruit should be ready for picking in July.

Sowing and planting

When growing tomatoes it is important to decide how many you intend to grow as if you are planning on growing a large number of tomato plants in your greenhouse then it is advisable to stick to the conventional method of sowing thinly in trays filled with seed and cutting compost. Whilst at this stage in the growing cycle the plants should be kept moist but not too wet and once seedlings have formed a pair of true leaves, prick them out into 3in pots filled with potting compost.

If, however, you are only planning on growing a few tomato plants then it will probably be easier to sow the seeds in 3in. peat pots of compost. Your other alternative is to buy in tomato plants from a reputable online garden centre or supplier and plant out once the seedlings reach 6-8inches tall and the flowers on the first truss are beginning to open. Water the pot thoroughly before planting and plant around 18inches apart.

Looking after the crop

During the growing process tomato plants will require a great deal of care and attention, especially if you want to get the best fruits from the plants. One of the first things you can do to ensure you get the best from your tomato crop is to tie the main stem loosely to a cane or wind it up a well-anchored but slack vertical string. When side shoots appear where the leaf joins the stem, trim these off when they reach approximately 1inch long.

When your tomato plants grow to around 4ft tall it is time to remove the leaves below the first truss. Remove yellowing leaves below fruit trusses as the season progresses but be careful not to overdo this process. Remember to water your tomato plants regularly as irregular watering could lead to blossom end rot or fruit splitting. You should also feed your plants with a soluble tomato fertilizer every time you water them and if you choose to grow tomatoes in a grow bag then you must water them regularly.

For best results adequate ventilation is essential during the summer months and if the temperatures reach 80ºF or more then you should take care to provide adequate shade. Mist or spray plants and gently tap supports during the growing process to aid pollen dispersion and fruit set and remove the tip of plants that reach the top of the greenhouse at 2 leaves above the top of the truss.

Soil Facts

Most tomatoes can be grown and do well in border soil and raised beds give better results than beds that are at ground level. Try adding in a little peat or small amount of compost before planting and mix in some Growmore fertilizer for the better results. You may have to be prepared to move or replace your border soil with each season as border soil is commonly known to become infested with soil pests and root diseases necessitating a need for the soil to be removed and replaced or sterilised.

Harvesting

You will know when it is time to pick your tomato fruits as they will be ripe and rich in colour. To remove the fruits safely from the plant hold the tomato in your palm and with your thumb break of the fruit at the knuckle (swelling within the flower stalk). Towards the end of the season you can begin to remove stems from the canes and supports and laid under cloches on a bed of straw. An alternative way to ripen fruit is to put them in a drawer next to some ripe apples which will produce the ripening gas ethylene.

Greenhouse Tomato Varieties

Ordinary Varieties

This group of red salad tomatoes contains some of the most popular varieties that are commonly grown across the UK. These varieties owe their popularity to the fact that they are reliable, full of flavour and can produce early crops.

• Ailsa Craig – produces bright medium-sized fruits that mature early and are a tomato accredited for their full flavour.
• Moneymaker – one of the most popular varieties amongst amateur gardeners; the Moneymaker produces medium-sized fruits but don’t have as fuller flavour as the Ailsa Craig variety.
• Alicante – similar in type to the Moneymaker variety, Alicante tomatoes are reliable, heavy-cropping and importantly are resistant to Greenback.

F1 Hybrid

F1 Hybrid tomatoes are very similar to the ordinary varieties but with a few added advantages including higher yields and a higher degree of disease resistance.

• Tumbler (Tumbling Tom) – this variety of tomatoes can be grown in a pot or in a hanging basket.
• Estrella – this tomato variety is extremely disease resistant which improves its appeal with some gardeners
• Eurocross – these tomatoes are an excellent choice for gardeners looking to grow plants in a heated greenhouse. They produce large fruits and are immune to Greenback

Beefsteak

Beefsteak tomatoes are large and meaty and may need support once reaching a certain size. There are 3 types of Beefsteak tomato; the true beefsteaks such as the Dombito, the F1 Hybrids such as the Big Boy and the Marmandes which are only really suited to outdoor growing.

• Big Red – the most popular of all the giant or beefsteak tomatoes the Big Red can produce fruit up to 1lb in weight if left to grow 3 fruits per truss.
• Dombello – considered one of the best beefsteak varieties the Dombello has large flattened globes that are borne early with very good flavour.

Novelty Tomatoes

Perhaps not as popular as red tomatoes, yellow or striped novelty tomatoes deserve more attention, especially when you consider that the first tomatoes sent to Europe were gold in colour and not red.

• Golden Sunrise – typical choice for anyone wanting yellow tomatoes, Golden Sunrise tomatoes are medium-sized and have a distinctive taste.
• Tigerella – these early maturing tomatoes are very distinctive thanks to their red and yellow stripes when mature.
• San Marzano – an Italian variety that is egg-shaped and has firm flesh.

Tomato Pests and Diseases

Tomatoes are susceptible to a variety of different pests and diseases, all of which are discussed in our guide ‘How to Grow Tomatoes Outdoors’ which can be seen by clicking here.

Plant Me Now is a leading online garden centre based in the UK. For more information about their extensive range of garden supplies including tomato seeds, Upside down tomato planters please visit the website at www.plantmenow.co.uk

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