Greenhouse tomatoes

Preparing the soil

The greenhouse border in which the young tomato plants are to be grown should be very well dug over during March, at the same time incorporating a good bucketful of well rotted compost from the heap to every square yard of soil. This is most important as, not only will the plants gain strength quickly, but the soil will tend to retain moisture more successfully when the warmer weather arrives.

Buying young plants

Unless sufficient heating is available in the house, it would be unwise to plant tomato seeds before the beginning of April as they do not particularly like cold conditions. In this case a few shillings invested in some good healthy plants from a shop or nursery will make up for the delay. These will have been grown under much better conditions than is possible in a cold greenhouse and will soon establish themselves when taken carefully from their pots and replanted in the greenhouse border. Alternatively they can of course be re-potted into 10” flower pots and placed onto the shelving. If the latter method is chosen the pots should be filled with some John Innes compost after the drain holes have been covered with crocks to prevent blockage. The pots should then be placed in position, two feet apart, and well watered. After a few days they are ready to be planted.


Whether planted in pots or directly into the greenhouse border, provision should now be made for ample staking and it is very easy to under-estimate the weight of a fully grown plant heavy with fruit at this time. Good strong bamboo canes should be inserted near to each plant being most careful not do damage the root system. It may be necessary to bind two canes together to get the required height and these should be tied securely to a horizontal wire which should be attached to the greenhouse and run the full length of the row. Where the height of the roof is limited it may be necessary to extend more canes along parallel to the roof.

When the planting has been completed and the stakes secured, each plant should be tied to its cane loosely enough to allow for the rapid growth of the stem. This should be repeated as the plants’ height increases.

Removing side shoots

As the plants gain height it will be found that small shoots appear between the main stem and each leaf stem. These must be removed and can easily be pinched out while small with the thumb and first finger. Throughout the season these shoots will continually appear and if allowed to grow would take away nourishment from the plant and weaken it. Keep a sharp eye then for these little shoots and get used to removing them regularly.

Setting the fruit

Because of the relatively small number of insects which find their way into the greenhouse and the possible lack of sufficient ventilation it is a good plan to help the flowers to pollinate by encouraging the pollen to transfer from one flower to another with the aid of a small camel hair brush. Simply transferring a little of the pollen in this way will help enormously the setting of the fruit. Alternatively a gentle shake of the main stem during a warm dry day will tend to dislodge the pollen from the flowers and distribute it into the air.

Each of the clusters of flowers which will eventually bear the tomatoes is called a “truss” and when the plant has grown sufficiently and five or six trusses have changed from flowers to tiny tomatoes it is time to stop the plant from growing any higher. This can be done simply by pinching out the growing stem at the top of the plant. At this time regular feeding with a good brand of tomato fertilizer is required and should be applied according to the instructions obtained with the product. This is usually sold in liquid form and can be added to the can when watering.

Ripening the fruit

When the trusses of fruit are fully grown and beginning to ripen it would help this process a great deal if some of the leaves, particularly those nearer the bottom of the plant, were removed carefully with a sharp knife.

This will allow as much light as possible to get to the fruit which will then ripen more readily. At the end of the growing season when there are still a few unripe tomatoes on the plants it would be as well to remove these and provided that they are sound wrap them separately in small pieces of paper and keep in a dry cupboard. They will then continue to ripen and allow the grower to clear his greenhouse without delay.

Tomato growing by ring culture

This method, favoured by many people in recent years depends mainly on the fact that the young plants are planted into bottomless pots, obtainable for this purpose at gardening shops, and stood on a layer at least 5” deep of well weathered ashes, clinker or gravel. The plants will very quickly adjust their growing habit to suit this method and will develop roots in the pots which will be used simply to feed the plant and another spread of roots down into the ash or gravel for the purpose of taking in water freely.

Care should be taken having set the plants in their containers to continue watering in the ring culture pot for the first three or four weeks until the plant has had a chance to develop its root system.

Ring culture

Recommended tomato varieties:

Ailsa craig – Medium sized fruit of good shape and flavour. Crops very heavily.

Dobies’ champion – Early variety with fruit of good size and flavour.

Market king – Medium sized round tomatoes of good flavour. Plants grow strongly.

Moneymaker – Probably the most popular for amateur or commercial growing. Crops heavily with brilliant scarlet tomatoes.

24. August 2013 by admin
Categories: Tips and Advice | Tags: , , | Comments Off on Greenhouse tomatoes


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