09:50 - 07 June 2011
By June your greenhouse tomatoes will be in flower and also growing very strongly. You need to keep up with their watering needs and to keep them well fed. In fact keeping up with your tomatoes is probably the best way to describe the next few weeks. If your tomatoes are in small pots they will quickly use up the water in the compost demanding thrice daily watering. Plants must be kept neither too wet nor too dry. Irregular watering can result in split tomatoes. They will also deplete any plant foods present and start to flounder. To get the very best from your tomatoes it is essential not to let them get stressed or pot bound or deprived of vital nutrients. The best way to do this is to keep up with their potting needs. As soon as you start to see roots poking through the bottom of the pots it is time to pot them into a larger container, the exception to this is when they are in their final planter. Bear in mind that one deep growing bag can support three tomato plants with additional feeding and if you are going to grow one tomato to a pot then you need to choose a pot that is at least 12inches (30cm) deep and of a similar diameter. For the best results pot your maturing plants into fresh, top quality compost or direct into the greenhouse border. The soil or compost needs to be free draining, easy to rewet and full of nutrients to give your plants the best possible start.
Most greenhouse tomato plants are grown as cordons (one stem trained vertically) or a V shaped plants with two stems trained, you can also grow bush tomatoes but these take up more room and don’t make the most of the eaves height. The following instructions assume you are not growing bush tomatoes.
Once your plants are growing strongly they will need support. The simplest way to do this is to attach vertical strings to horizontal greenhouse bars and tie your plant stems in as they grow. Don’t tie them tight or this will restrict the flow of water and food through the stems, instead loosely wind the main stem up the vertical twine as the plants grow.
Remove all side shoots that form between the leaf stem and the main stem, these will use up precious water and energy that should be going to the main plant. Pinch them out as they form.
When your plants are 5ft tall and have several trusses of setting fruit, cut off the bottom leaves up to the first truss, this will improve air circulation around your plants and let the light in to ripen the fruit.
Feed your plants weekly (or as directed) with a good tomato food. Don’t cut corners on the feed, a tomato food contains all the trace elements and micronutrients that your plants need to develop healthy tasty fruit. It also reduces the risk of some tomato diseases such as blossom end rot.
Pick the fruit as it ripens to reduce the load on your plant and also to keep it setting new fruit. If your fruit is slow to ripen then place a few banana skins around the plants, which will give off a ripening accelerator that will speed the process.
Keep a watch out for pests and diseases and act swiftly if any are seen. Tomatoes are susceptible to a vicious fungal disease called blight that can wipe out a whole crop. Watch out for black patches forming on the leaves and stems. They can also be affected by common greenhouse pests such as aphids, whitefly and red spider mite as well as a variety of mineral deficiencies that are best avoided by feeding correctly.
Tomatoes can seem to be high maintenance, but once you’ve tasted the flavour of a sun warmed, ripe fruit there really is no going back.
