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Growing Tomatoes

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Introduction

Tomatoes are sub-tropical plants originating in South America
and hence are partial to fairly hot dry conditions. However,
many varieties, particular bush varieties, are now suitable for
growing outdoors in the UK although you will need to protect
them from frosts in mid to late Spring. If you have a greenhouse
then this is the place to grow your tomatoes – they will be
protected from frosts during the early growing season and from
damaging winds throughout their lives. You will also be able to regulate
the amount of water and food they are given more easily than if growing
them outdoors.

Selecting Plants

The easiest way to get started is to buy young plants – you should look for compact, sturdy looking plants which should be dark green in colour with no yellowing of the leaves at all. Reject any ‘leggy’ plants, i.e. tall plants with long stems and relatively few leaves as these plants have had insufficient light during their early growing phase. Also look for pots with moist compost as young plants which have been allowed to dry out will be under stress and less likely to produce good quality crops. See the end of this article for growing from seed.

Location

Greenhouse grown tomatoes can either be grown direct in the ground if your greenhouse has a border or in pots (or possibly grow bags). Growing directly in the ground will probably produce the best results initially – mainly due to the larger soil mass producing more constant conditions for the roots (temperature and moisture). However, perfectly good results can be had by growing in pots and there are advantages to pot growing, principally that the compost can easily be changed each year to prevent the build up of disease organisms and to provide a known balance of nutrition. Tomato plants will grow outdoors in almost any soil conditions – I have experienced success in hard compacted clay soils as well as peat based bought composts. However, a good water retentive soil, rich in organic matter, will produce the best results for the least
effort. If growing outdoors, choose a bush variety and plant in a sheltered, preferably
south facing, position.

Planting and Care

When planting your tomatoes into their final growing position
water the area well before planting and put the plant slightly lower
in the ground than it was in the pot. If growing a bush variety then
support is not strictly necessary although if it is outside and exposed to
any sort of winds then it is probably best to provide some support to
avoid disappointment. Cordon varieties with a single tall vertical stem will
always need a cane or stake for support and will need to be tied into the
stake as it grows. After that it is just a case of watering the plants to
maintain a moist (but not permanently wet) compost and feeding regularly with a tomato fertiliser. Avoid high nitrogen based fertilisers as this will result in a very healthy, leafy plant but not much fruit. Cordon varieties will need side shoots removing throughout the growing season to limit the amount of energy the plant spends on producing leaves and encourage the production of fruit. Towards the end of the growing season (late July or August) the plants will be as tall as you want them to be and hopefully have six or seven good fruit trusses. At this point the growing tip can be pinched out to encourage the ripening of the fruit. Remove any brown leaves immediately and dispose of them.

Ventilation and Temperature Control

Although tomatoes enjoy hot conditions – they can get too much of a good thing! The best method of ventilation in the greenhouse is an automatic opening roof vent – if you haven’t got one it would make a good birthday present. Failing that take note of any particularly hot days and make sure you open up the windows and/or doors in the morning and close down again at night. Damping down at the end of a hot day will be much appreciated by your tomatoes – just spray the greenhouse floor and windows with water (and the plants) to cool everything down and create a nice humid atmosphere.

Harvesting

The best bit – make sure you get the first fully ripened tomato and
eat it straight from the plant while it is still warm and taste that
incomparable flavour of summer. After that if you have done your
job correctly there will be more tomatoes than you can sensibly eat
and your family, friends and neighbours will appreciate your glut of
home grown fruit as much as you do.

Tomato Pests and Diseases

Whitefly

Whitefly are the most likely pest to affect your tomatoes. Adult flies look like tiny moths and lay eggs on the underside of leaves; the growing larvae feed on the leaves, leaving a sticky secretion which in turn can attract other diseases. As soon as you see any eggs, try spraying with water to wash them off and remove others by hand as comprehensively as possible. If the infestation looks like getting out of control, there is no alternative to spraying with an insecticide – otherwise your entire crop will be ruined.

Red Spider Mite

These are normally only a problem in dry times. The mites are not visible but their presence is indicated when the leaves become mottled and yellowing. There is a really simple solution: spray the plants with a fine mist of water as often as possible - red spider mites hate moist conditions.

Aphids

You don’t want to use chemicals if you can possibly help it so if the greenfly start to move in there is only one solution – squash them between your finger and thumb!

Foot and Root Rot

Foot and Root Rot in tomatoes is often caused by irregular
watering, the base and roots of the tomato plant begin to rot
causing the leaves to discolour and the tomato plant may eventually
collapse. The key is regular watering to keep the compost MOIST BUT
NOT PERMANENTLY WET.

Growing From Seed

The beauty of growing from seed is the vast array of varieties you can choose
from, unlike the local garden centre where you will be lucky to find more than four varieties on offer. Having decided which variety or varieties to grow, getting started is really simple you sow the seeds in a pot and in about eight weeks you will have small plants which will be large enough to plant out. By mid-summer the first naturally sun-ripened fruits will be ready to harvest and the treat will begin and continue throughout the summer.

Start your tomatoes off by sowing seeds in pots something like 8 weeks before you expect the final frosts of the year – so you will need to think about sowing between mid February and early April depending on where you live. Leave them to germinate on a windowsill or in a propagator somewhere that is warm and frost-free and with absolutely as much light as possible.

How to sow: fill several 7.5cm (3in) pots with seed compost, lightly firm the surface and water. Put a single seed in the centre of each pot – tomato seeds are very good germinators and you will almost certainly have 100% of the seeds you plant germinate. Cover with a small amount of compost and clearly label the pot - keep the compost moist but not wet.

Growing on: when the roots start to come through the drainage holes in the bottom of the pot, transfer the plant into a 12.5cm (5in) pot, taking care not to damage the roots, and water in well. If the plant is getting tall, tie it to a small cane for support. If planting outside harden
off the plants by placing them outdoors during the day for a few days.
If you are going to grow them in a greenhouse then the plants will
be big enough to be transplanted to their final growing position
approximately eight weeks after germination. If the young plants
have been raised on a windowsill in the house they may be a bit
taller and thinner than is ideal due to lack of good light. In this
case do not be afraid to plant the young plants deeper in their final
growing position than they were in the pots – this will help support
the plant and new roots will form on the buried stems. Keep an eye out
for late frosts and put a little heat in the greenhouse if necessary.

Buy seeds from Thompson and Morgan.