Techniques for growing great tomatoes

Horticultural expert, Klaus Laitenberger talks about getting the most from these delicious nightshades. 

THE Latin name for tomato, Lycopersicon, derives from the Greek word, ‘lycos’ a wolf, and ‘persicon’ meaning a peach. ‘Esculentum’ means edible.

Tomatoes are certainly one of the most exciting tunnel and greenhouse vegetables you can grow. The flavour of home-grown tomatoes can never be matched by the bland and thick-skinned supermarket varieties.

In fact, modern tomatoes are bred so that they will last for weeks on supermarket shelves and don’t bruise when handled.

The other trouble is that many of them are grown without soil, often in straw-bale culture that is drenched with artificial fertilisers and with supplementary heat and lighting. They are nearly as badly-treated as battery-farmed hens.

History

The tomato grows wild in South America. It was first cultivated in Mexico by native Americans and brought back to Spain by Spanish conquistadores. In 1544 it reached Italy. Soon after, it spread throughout Europe, but it took a long time for the tomato to turn from a pretty ornamental plant into a vegetable.

Soil and site

Tomatoes require a very fertile soil. Just imagine a full-sized tomato plant — well over two metres tall and all the hundreds of fruits it produces.

It surely needs a lot of nutrients. The best feed is composted farmyard manure or garden compost. I usually incorporate a full wheelbarrow of composted manure into the soil for every three square metres.

If tomatoes are grown in pots or growbags, ensure that the pots are large enough (40l) and that you don’t plant more than two plants per growbag.

I have to admit I’m not a fan of growing tomatoes in growbags or pots as their growing space is far too restricted. Obviously if you haven’t got a suitable spot in your border, growbags may be the only option.

Sowing

Tomatoes need to be raised on a heating bench or warm south-facing windowsill. Seeds are best sown any time between February and March. I sow the seeds into traditional open seed trays (not modular trays) or pots.

Seeds should be sown thinly into the trays (about 70 seeds per standard tray) or about 7 seeds into a 9cm pot. Then cover thinly with sieved compost. Keep the trays moist at all times — never over water them or let them dry out.

The tomato seedlings should emerge after 10 days. It is very important to prick out the seedlings as early as possible, ideally into 10cm pots containing a richer potting compost.

Remember to hold the seedlings by the seed leaves (cotyledons) and plant so the seed leaves are just above soil level. During this stage, the plants should remain on the heating bench or your south-facing windowsill.

Young plants in pots must be spaced out as soon as their leaves are touching — roughly about every three weeks. If you fail to do this, the plants will become weak and spindly.

Planting

When the plants are well rooted in their pots and before they get pot-bound, they can be planted into the greenhouse or polytunnel. The best time is in May. Tomato plants can be trained up strings that are attached to an overhead wire. After digging the planting hole, lay the bottom part of the string into the hole and tie the other end to the overhead wire. Plant the tomato plant on top of the string and cover and gently firm the soil around the plant to leave no air pocket around it. If your tomato plants have become leggy you can plant them deeper. This will strengthen the plants.

Spacing

The plants should be spaced out 50cm apart. You can have a single or double row per bed. The yield is obviously higher from a double ro,w but a single row usually produces healthier plants. Every week you have to side-shoot your plants.

Many beginners find it difficult to distinguish between a normal leaf, a side-shoot, a flower truss and the main stem. Just remember the side-shoot is the one between the main stem and a leaf, always the one in the middle.

Side-shooting tomatoes

No matter how long the side shoots have become — and even if they already have flowers on them — you have to remove them. When the side shoots are small you can nip them off with your fingers, but when bigger you need to use a sharp knife or secateurs. The other weekly job is to wind the growing plants around the twine and remove the lower leaves that start to turn yellow.

Harvesting

You can expect your first harvest of tomatoes in July, possibly slightly earlier in very warm parts. My favourite variety, Sungold F1, is always the first one to ripen and often the one that lasts longest. It is also high-yielding. You will often get up to 400 most delicious cherry tomatoes from it. It is important to harvest your tomatoes regularly — at least once a week — otherwise the fruit becomes over-ripe and rots or splits. You can expect to get a regular supply of tomatoes until the end of October and in some years right into November.

* Klaus is holding a gardening weekend at Renvyle House Hotel, Connemara, from Friday, February 19 to Sunday, February 21. See garden notes, right, for more information.


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