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Growing Tomatoes Outdoors

Growing tomatoes outdoors is a chancy business in Britain, even in the sunny south of the country. Tomatoes are very dependent on having enough warmth for enough time to grow and crop before the cold comes again.

Growing Tomatoes Outside

Growing Tomatoes Outside

As if that wasn’t enough in recent years some exceptionally virulent strains of blight have arisen and the conditions for blight to survive, warm and humid, have become more common.

The general rule is that the further north you go the less the chance of success but it all depends on the micro-climate of your vegetable plot.

Ideal Site for Growing Tomatoes Outside

The ideal site for growing tomatoes outdoors will be south facing, sheltered from the wind, warm and not in a frost pocket. Wind can make more of a difference to temperature than most people realise.

There’s not much you can do about the sun or lack of it, but you can improve shelter from the wind by erecting windbreaks in exposed spots.

Preparing The Soil

In the spring, either dig a trench or at least holes a foot (30cm) square and the same deep at the planting spots. Half fill with good home-made compost. If you have some rotted manure, especially sheep manure which is rich in potash, add some of that as well.

If you have wood ashes, add about 4 oz (125gr) per hole or foot run of trench and fork it into the compost. Top up with soil and leave until planting time. If you can cover with black weed-suppressant fabric this will help warm the soil as well as stop weed growth.

Start your seeds off under heat in March or early April and bring on in pots until planting time in your area. This is covered in detail in Sowing and Starting off Tomatoes.

When to Plant Out Tomatoes

The worst thing you can do is to plant out too early. A cold spell will check growth at best and kill the plant at worst. It is unlikely to be much earlier than mid-June even in the south. Check out Ideal Temperatures for Growing Tomatoes

How to Plant Out Tomatoes

It is possible to encourage tomato plants to develop more roots by planting deeply. If you look at the bottom of the stem you will see what appear to be hairs. These hairs will grow into roots when covered with soil.

With cordon tomatoes, especially if they are leggy, plant on a slope or even horizontally, bending the stem carefully to the vertical where it leaves the ground. The more roots the more nutrients the plant can take in.

Supporting Outdoor Cordon Tomatoes

Stake using a stout bamboo cane or a hazel pole by each plant and loosely tie each plant to its pole. Do not tie too tightly or the stem may be damaged as the plant grows and it thickens.

Please don’t waste your time constructing complicated supports like runner bean supports and stringing your tomatoes to a cross-bar as so many American videos suggest on Youtube. Keep it simple and tie to an upright stake that won’t collapse in a summer storm.

With cordon (pole) tomatoes, inter-plant with fast growing crops such as lettuce if you wish and mulch preferably with chopped comfrey leaves and lawn mowings. With bush varieties, plant through the weed mat. The weed mat will help keep the fruits clean and helps with slug control.

Feeding and Watering

By each plant, both cordon and bush, insert half a plastic pop (soda in the USA) bottle with the top and bottom cut off to form a pipe to take both water and liquid feed down to the roots.

Once the fruits begin to set, commence feeding either with commercial tomato fertiliser or with comfrey liquid.

End of Season

At the end of the season before the first frost, I harvest all the green tomatoes of reasonable size and these can either be ripened indoors or used in chutney etc.

You can also hang up the vines with fruit on in a frost-free, cool dark place and they will slowly ripen. If kept in a bowl with a ripe banana they will ripen quickly due to the ethylene gas given off by the banana.

If a mild frost is threatened you can try covering with horticultural fleece to keep the plant going. My own experience is that when the weather turns, you may as well give in as the low temperatures in the daytime will not favour growth.

If you are growing cordon tomatoes outside, you can lay these down onto straw or suchlike and cover with a cloche. If you don’t lay onto something, you’ll just be bringing the slugs a meal!

Best Varieties for Outdoor Planting

Varieties where the supplier states suitable for outdoor growing are obviously best. The faster they produce fruit the more chance of a decent crop in our short season. Sungold, Gardener’s Delight and bush varieties that take up too much room for a small greenhouse anyway like Roma and San Marzano will do well.

Often heritage tomato varieties will do well as they date before greenhouses became affordable to the masses.

With the blight problem getting worse it is well worth looking at blight resistant tomato varieties as well.

Further Information: Tomato Growing Guides