HOW TO GROW GREENHOUSE TOMATO PLANTS FROM SEED
Tomatoes are grown as tender annual plants in most regions, but they are actually classed as short lived perennials in the tropics of south America - their native environment. To get the most out of your tomato crop they will require high light intensity and a temperature of 21 - 24C, however they will lose vigour if kept above 27C or below 16C. Just remember that tomato plants will not tolerate exposure to frost.
Sowing the Seed
Tomato seed is quite easy to handle and is best germinated using a standard seed tray filled with John Innes 'Seed and Cutting' compost. Space the seed evenly and then cover with about 1.5mm of compost. Tomato seedlings will usually germinate in about 7 to 14 days at a temperature of around 21C . For the best sowing times, see the recommendations listed in 'greenhouse' or 'outdoor' cultivation below. Pot tomato seedlings on when they are large enough to handle without the need to touch the stem.
Just by handling the leaves, transplant them carefully into 3 inch pots using John Innes No.1 potting compost. If only a few plants are required, sow two seeds into a 3 inch pot and after germination remove the smaller plant. Take care not to let the plant and seedlings get cold as frost, cold winds and draughts will cause the plants to turn bluish and in most cases die. If you live in a cold area wait a few extra weeks until the air temperature has risen. Check the compost at all stages for dryness. This is vital in the initial stages of germination as drought can cause poor germination or failure to germinate at all. If this is the case, add a little clean water from below, being careful not to overwater. Too much water can kill seedlings just as easily, as it can spread water borne fungal diseases such as 'damping off'
For greenhouse tomatoes first pick a recommended variety such as 'Santa', 'Matador', 'Sungold', 'Money Maker' or 'Supersteak' and sow as directed on the individual seed packet. This will generally be from late December/early January onwards and straight into 3 inch pots.
Plant the young plants when they are about 6-8 inches tall and the flowers of the first truss are just beginning to open. If you are planting into your greenhouse border make sure you have dug in plenty of organic compost during the winter.
If you have used the border before for tomatoes, it is better to change the soil or sterilise it before using it for tomatoes again. This will help avoid soil pests and root diseases becoming a problem. Just before planting, rake in a general purpose fertiliser. If you are going to use a grow bag or pot just remember they will require a lot more watering and care. Plant approximately 45cm (18in) between the plants and 75cm (30in) between the rows. In a growbag, generally plant no more than two plants per bag.
How to train or when to pick your fruit will depend on the varieties and types of tomatoes grown. Cordon (indeterminate) varieties will need their side shoots removed, determinate varieties may stop flower production after several trusses, but upward growth can be carried on by training up the topmost side shoot.
Bush varieties will remain low and will not need their side shoots removal.Tomatoes require a lot of water and feed to get the best fruit. Water little and often for the best results. Feed with a general liquid feed until the first truss is formed then alternate with a high potash feed. This will encourage more flowers and fruit.
For related articles click onto the following links:
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HOW TO GROW OUTDOOR TOMATO PLANTS FROM SEED
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HOW TO GROW TOMATOES IN POTS
HOW TO MAKE A TRADITIONAL ITALIAN TOMATO SAUCE