Growing Tomatoes - outside

Nothing beats the flavour of a freshly picked, home grown tomato. Tomatoes are a relatively easy to grow plant and can be grown from seed or you can purchase plants from a garden centre, plant nursery,or garden shows. If growing from seed start them off indoors, using a propagator or place the pots in a plastic bag and keep on the windowsill. It's best to start seed in March to early April if they will be growing outdoors. If your tomatoes will be grown in a greenhouse, seed can be sown earlier, sow from mid-January to early February (heated greenhouse) or late February to mid-March (unheated greenhouse). 
Tomatoes are very easy to grow from seed. Start them off indoors, using a heated propagator or just place the pots in a plastic bag and keep on a windowsill. 
Fill a 9cm (3½in) pot with seed or multi-purpose compost Level and firm the compost, then water
Sow the seeds on the compost surface, spacing them evenly, and apart, to prevent damping off as the seedlings grow
Cover the seed with a layer of vermiculite
Keep plant pots around 21°C (70°F), until seedlings emerge
Seedlings emerge usually between five and ten days. Keep them in the best-possible light (such as a sunny window sill or greenhouse) and at a temperature of around 18°C (65°F) to prevent seedlings becoming long, thin and ‘leggy’. 
Seedlings should be large enough to prick out into separate pots of multi-purpose compost two weeks or so after sowing and before the first true leaves have formed:
Ideally, fill pots a few days before pricking out, water well, and allow to warm up to room temperature to reduce the chance of the seedlings damping off.
Hold seedlings by their cotyledons (seed leaves) to avoid damage to the delicate stems

Make a hole in the compost big enough to take the roots and lightly firm the seedling in place

Water in with tepid water

Reduce the temperature to 16ºC (60ºF) when plants reach 15cm (6in) high

Do not plant outdoors until all chance of frost has passed. here in the North East of England that may be mid-June.

Hardening off: If you are growing tomatoes outside you will need to "harden off" the plants, which means getting the plants used to the colder conditions outside, as opposed to the more controlled conditions in a greenhouse. The easiest was is by placing the plants outside for increasing amounts of time, starting on days when the weather in late spring is warm, but only leave outside overnight once all risk of frost has passed. 

If you want to grow just a few plants try planting them in pots, planters or growbags. Don’t forget to water regularly as they will tend to dry out quickly. Just a couple of plants will be sufficient to give you plenty of tomatoes in the summer.
Tomato plants can be cordon varieties that need staking and tying in, bush varieties, and there are even tomato plants designed to grow in hanging baskets. 

Cordon varieties (Indeterminate or vine types) are single stem varieties that need to be trimmed and tied-in/supported. These can grow quite high but in the North of England the stem should be stopped after the 4th truss has set to hasten ripening before the autumn frost arrive. 

Cordon varieties worth trying are:

Ailsa Craig - Produces good flavoured, bright medium-sized fruits that mature early

Tigerella - tangy flavour, early cropping, striped tomato, grows well outside

Golden sunrise - medium-sized, yellow tomatoes with a distinctive taste

Tumbler (tumbling Tom) - for growing in pots or hanging baskets

Gardeners Delight – A favourite for experienced gardeners, this variety creates bite-sized, tangy, tomatoes. Perfect for growing outdoors

Bush types(Determinate) - These types are much easier to grow outdoors, developing bushes 1-4ft high and creeping plants that are less than 9 inches tall. They may require a limited amount of supporting and/or staking, should NOT be pruned or "suckered" as it severely reduces the crop, and will perform relatively well in containers

Types to try -

Red Alert - Provides early yields of small fruits with good flavour

Sungold - A really nice tasting light orange cherry tomato. 

Marmande and Super Marmande both produce large (beefsteak) fleshy tomatoes of excellent flavour, and definitely will need staking and tying.

Choose a bright, airy spot. Plant tomatoes where they will get at least 10 hours of light in summer. And leave room between plants for air to circulate. 

If growing directly in the garden or in raised beds ensure you don't plant in the same place every year alternate between spots and you diminish the risk of soil borne diseases such as bacterial spot and early blight.

When buying tomato seedlings beware for over lush and over large plants because they may not actually grow straight away 

Bury the stems - Plant your tomato seedlings up to the first true leaves. The stems will quickly sprout new roots. More roots means a tough stem and more fruits.

Water deeply but infrequently - Soak your tomato bed once a week, or every five days at the height of summer. Water directly onto the soil and, not on the leaves.

On cordon types pinch the suckers - Prune off these non-fruiting branches. This directs the tomato plant's energy into growing bigger better fruit. 

With outdoor tomatoes particularly in the North of England stop the plant at 4 trusses unless you want lots of green tomatoes

Stake them high - Use 6-foot canes for cordon varieties like 'Ailsa Craig' or 'Gardeners Delight' . Put in the canes when transplanting to avoid damaging roots. Tie in at 1ft intervals

Add compost - While the first fruit is ripening, encourage new growth and continued fruit set by scraping compost around the stem. 

It's an idea that after you plant tomatoes in your garden, put in another set a few weeks later so all of your harvest doesn't come at once. 

Providing average weather conditions here in the North East tomatoes will normally be ready for harvesting in mid-August. They will be ripe and full in colour when they are ready.