Ripe and unripe tomatoes still on the plant

Greenhouse or Outdoor Cultivation

There's no doubt that growing tomatoes in a greenhouse results in earlier, heavier harvests than outdoor cultivation. Because of the protection a greenhouse offers, sowing can start in early spring and there is a longer growing season. The environment inside a greenhouse is kinder, there's no rain and the temperature is warmer and more constant without wide fluctuations, the conditions easily regulated so that they remain the optimum required for growth and pollination.

It's true that at the height of the summer, sunlight can become too intense in a greenhouse. This might cause scorching or overheating but there are several ways to protect your tomato plants. The glass can be temporarily painted or shades fitted. Good ventilation and temperature control can be achieved by adjusting opening roof vents (automatically or manually), louvres and the door, to create a healthy throughput of air that guards against fungal diseases.

Greenhouses range in size from wall gardens to impressively large semi-professional structures that suit every location. Built from aluminium or timber with individual specifications, to discover which one best suits your requirements.read our blog: Which greenhouse should I buy and why? 

Health Benefits

Tomatoes are excellent news for your health especially when cooked with a good olive oil as they are rich in potassium and anti-oxidents.

These are associated with lowering your risk of suffering a stroke, heart disease and cancer,. Other compounds are thought to prevent macular degeneration, carotenoids may help your skin avoid UV damage, and vitamin K aids blood clotting and bone health.

So what's not to like about these shining red globes of refreshing flavour that originate from the Americas? Very little, as they are so easy and very satisfying for anyone to successfully grow.

Vine or Bush Tomatoes

Varieties such as Ailsa Craig and Alicante are grown as a vine with trusses of fruit on a single upright stem tied to a cane, these are traditionally grown in a greenhouse. Bush tomatoes such as Tornado and Tumbler have a number of stems and are ideal for outdoor borders and containers including hanging baskets if they are a dwarf variety.

Which Variety Is Best To Grow?

Taste naturally is important, size also matters, different colours create the most visually attractive meals, and you also have to consider what the tomatoes going to be used for.

The smallest, and sweetest, are termed 'cherry' tomatoes. These bite sized explosions of flavour are borne on long trusses and include the ever popular Gardner's Delight and Sweet Million.

'Salad' tomatoes are a little larger, Moneymaker is probably the best known due to its reliable large yields even when gown in poor conditions and versatility. Aisla Craig has been around for over a century, while Shirley is disease resistant and matures early.

'Plum' tomatoes are the classic Italian kitchen variety, perfect for cooking, Astro Ibido and Rio Grande make great sauces, and choose the thick fleshed Incas if you want an early maturing variety.

Finally, 'Beefsteak' tomatoes are the largest type and these are ideal for stuffing. Marmand is a famous variety along with Brandywine which has outstanding flavour and the ribbed Costoluto Fiorentino.

Tomatoes Are Not All Red!

You would be excused in thinking that tomatoes are universally red as these are mostly the only ones that are available in the shops. This is why growing your own is such a wonderful way of discovering that different coloured tomatoes exist and just as delicious, with their presence in any dish introducing vibrant interest.

Orange, yellow and striped cultivars include the orange striped Tigerella with large tangy fruits, Golden Sunrise and Sungold, a popular sweet and disease resistant variety. There are even 'black' tomatoes, notably Black Cherry with lots of delicious brown fruits, and Black Russian, a medium sized tomato that is purple brown and can be grown in a greenhouse or outdoors.

Outdoor and Indoor Varieties

For outdoors, you need a tomato that matures quickly (as they will be planted out later than in a greenhouse and harvested earlier) and they will nees to succeed in harsher open air conditions. So as a general rule, if you are growing outdoors it probably best to choose a bush tomato, particularly a 'heritage' type such as The Amateur or Brandywine which have been around a long time, before affordable greenhouses became available to the public.

Roma and San Marzano will do well and blight resistant varieties would also be useful such as Crimson Crush and Lizzano. Best vine varieties would include Gardener's Delight, Money Maker and, for something a bit different, Tigerella. Garden Pearle is brilliant if you want tomatoes tumbling from a hanging basket.

Best greenhouse tomatoes tend to be vine varieties as they make efficient use of the available space and, because the growing season is longer, early maturing tomatoes are not as important, Gardener's Delight, Sungold and Ailsa Craig are always popular but there are many, many others and your choice will depend on the size you prefer and how they are going to be used.

Sowing Seed

Young plants can always be bought from garden centres, markets and car boot sales but many gardeners prefer to grow their own from readily available seed.

Although modules and other media can be used, seed is traditionally sown in a tray filled with compost from February to March for indoor tomatoes. If growing the tomatoes outside, sowing takes place a little later.

Place on a windowsill or use a propagator, the temperature to aim for is 18C – 21C. Transfer the seedlings to 3in pots when they are large enough to handle and grow on in a temperature between 10C – 12C. And then plant out in a cold greenhouse in mid-spring.

Outdoor tomatoes must be hardened off, i.e acclimatised to an outdoor environment, before being planted out in late spring. This is best done in a cold frame. These can be bought usually as a flat pack and fabricated or you can build one yourself, basically just a box with a perspex lid. Each day open the lid slightly wider, closing it at night. Then leave it fully open during the day and increasingly open at night, until it is fully open day and night, and the plants will be ready to plant out.

Planting Out

Plant either two to a grow bag, individually in 15in pots filled with good potting compost or 12-18ins apart (bush varieties need 3ft) in borders which have been well prepared with fresh compost and manure, any outdoor location needs to be sunny and sheltered.

After planting, water in each plant but then don't be over generous with watering until the first flowers emerge, then gradually increase the amount as the fruits swell. Containers and grow bags need daily watering (twice daily in extreme heat), those in borders every few days preferably using a pipe that transfers all the water to the roots. The regularity of watering is important, do not let the plants dry out, perhaps as much as two pints per day are necessary, although slightly less for cherry tomatoes. Introduce specialist fertilizer once a week to start with and then at least twice a week as the fruits swell.

Maintenance

Regularly tie in new growth and remember to remove side shoots from vine tomatoes. After four or five trusses have formed pinch out the growing tip. Later in the season, remove some lower leaves especially ones that have started to yellow to allow light and air to circulate. Bush tomatoes don't necessarily need staking but you may want to place straw or bark underneath to keep any fruit off the ground.

Greenhouse plants can be harvested from mid-summer into the autumn, leaving the calyx on the fruit. Outdoor varieties will be ready in late summer.

Common Ailments and How To Treat Them

Blossom End Rot

A black / brown patch appearing on the base of the fruit caused by lack of calcium. Plants that have restricted root space i.e. in pots and grow bags are most at risk as not enough water is flowing through the plant to supply calcium the fruits. So it's very important that the compost does not dry out and is consistently moist. Regular watering, once or twice daily is recommended, mulching to retain moisture and, if this is not possible, fit an automatic watering system.

Blight

This is particularly prevalent outdoors when leaves turn brown, curl up and die, fruits will turn brown, shrink and rot. There's no cure but spraying with a copper fungicide such as Bordeaux Mixture in damp or humid weather might prevent the problem. If blight does occur you must remove and destroy all foliage, use fresh compost or grow elsewhere the following season.

You might also try blight resistant varieties such as Crimson Crush F1 which offers deliciously large fruits or Lizzano F1 if you prefer cherry tomatoes.

Leaf Mould (Botrytis)

This is largely a indoor problem when fluffy white / grey mould appears on various parts of the plant. Remove and destroy affected plants. Increase ventilation, reduce humidity and ensure remaining plants have sufficient room. Water only to the base and you may have to apply a fungicide.

More Information

https://www.gardensite.co.uk/help/guides/greenhouses/heat-your-greenhouse/

https://www.gardensite.co.uk/help/guides/greenhouses/greenhouse-faqs/

https://www.gardensite.co.uk/help/guides/greenhouses/buying-a-lean-to-greenhouse/

https://www.gardensite.co.uk/help/guides/greenhouses/greenhouse-base-faqs/

https://www.gardensite.co.uk/help/guides/greenhouses/successfully-growing/

https://www.gardensite.co.uk/help/guides/greenhouses/allotment-greenhouse-guide/