How To Prune Tomatoes in the UK
 

Pruning Tomato Plants to Shape

As far as pruning is concerned, tomatoes in the UK come in two forms, bush (or determinate) and upright (indeterminate or cordon). The difference between the two types of tomato plants is that bush varieties naturally produce a limited amount of side stems, they "know" when to stop producing foliage and when to start producing tomatoes. For this reason they need very little pruning.

On the other hand, upright tomato varieties don't really know when to stop producing and if left alone they will produce far too much foliage and too few tomato fruits. Careful and frequent pruning will help them stop producing foliage at the correct time and they will then produce a much better crop of edible tomatoes.

Bush varieties do well for cultivation outdoors because they require little pruning for most of the season. Remove any yellow or decaying foliage as soon as possible to avoid the spread of disease.

It's also a good idea to prune any stems that are touching or very near to soil level. If left to touch the ground they may well catch soil borne diseases which then go on to infect the whole plant.

Upright / cordon varieties are commonly cultivated in pots, grow-bags, the greenhouse and sometimes outdoors in open soil. When the first fruits begin to form, the plant will produce side-shoots in between the main stem and the leaf stems.

These side shoots (see arrows in diagram on the right) should be removed by pinching them out with the fingers. If allowed to grow they will produce a mass of foliage but few tomatoes. Any shoots which have been overlooked and allowed to grow should also be removed (see X in diagram). If you click the picture on the right, a real picture will appear identifying two side shoots on a real tomato plant.

Lower leaves which show any signs of yellowing should also be removed to avoid the risk of infection.

When the plant has developed six or seven trusses of tomatoes (normally around July time), 'stop' the plant by breaking off the growing tip. If any more than seven trusses of tomatoes begins to develop, pinch them out to encourage the plant to produce good quality tomatoes rather than an abundance of low quality late-maturing fruit.

When to Harvest Tomatoes

Pick as soon as the fruits are ripe (colour and size will identify this) for the best flavour - eat as soon as possible. This also encourages the production of more fruit. As soon as a frost threatens (around October in the UK), harvest all the fruit immediately and ripen them on a window sill. With upright varieties, it is possible to gently flatten the plants onto the soil and cover with horticultural fleece to protect them from the frost.  

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