Tomatoes are very easy to grow, making them one of the most popular food plants with amateur gardeners and professional growers alike. While they will quite happily grow outdoors in the UK during the warm summer months, best results will come from those that are grown in the greenhouse.
Plants that are grown in the greenhouse are not exposed to the elements, resulting in smoother and much more tender skins. They will grow faster and produce a higher yield than those grown outdoors and some people would argue they taste much better too.
Why grow tomatoes in a greenhouse?
The greenhouse provides ideal growing conditions for tomatoes, which will thrive on a steady supply of warmth and humidity together with regular feeding. Tomatoes that are grown in the greenhouse are also much more accessible than those grown outdoors.
Outdoor grown plants may not get as much attention as they need should the weather turn unfavourable for any length of time. They are also more likely to succumb to pests and diseases than their greenhouse-grown counterparts.
Benefits of growing tomatoes in a greenhouse
Greenhouse grown tomatoes are generally more uniform in shape and size, which is mainly due the near constant daytime and night time temperature ranges of their environment. Regular feeding and the removal of side shoots and other routine maintenance tasks can also contribute to the general health of the plants.
Also, within the protective confines of a greenhouse the plants are allowed to grow taller and therefore produce more flowering and fruiting trusses. Noticeably, the overall quality of greenhouse tomatoes tends to be higher than those grown outdoors.
Cordon Vs Bush Type
Although you can grow any type of tomato plant in a greenhouse, the bush-type, which fall into the determinate category, take up a lot of room due to their sprawling habit. The cordon type, also known as indeterminate, are those that you can train on an upright support such as wires or canes.
Therefore they require less floor space and overall, they will be much more productive. There are many tried and trusted favourites for greenhouse growing, some of which will also grow well in the open ground.
Flower pollination
Tomatoes grown outdoors are best restricted to 4 trusses because further trusses are unlikely to mature as the summer months draw to a close. However, it’s not uncommon to allow twice this amount to mature for those grown in the greenhouse, especially if they have been started off early. One important point about growing tomatoes in a greenhouse is to ensure there is adequate side and top ventilation.
Not only does this help to keep the plants cool, it also aids with pollination. Outdoor plants will have the wind and pollinating insects to do the job for them but indoor plants have neither benefit. Some gardeners will hand pollinate to be sure the flowers are fertilised.
Compost choice
Tomatoes can be grown in grow bags, large pots of quality compost or in beds, which have been prepared in advance. If growing in beds under cover then ensure the soil is free of weed seeds and damaging insects.
For best results use a 50/50 mix of organic matter and multi-purpose compost. A John Innes No.2 compost is ideal for growing tomatoes. In all cases, begin feeding tomatoes when the first flowers begin to set and the tiny fruits are just visible. Apply a well-balanced NPK liquid feed at least once a week up until the last truss is harvested.
Caring for greenhouse tomatoes
Cordon tomatoes will need regular tying to their supports, using twine or soft twist ties. Some of the plastic, snaplock and clip ties, which are available in garden centres could be damaging to the plant’s delicate stems so are not advisable. Side shoots should be routinely removed along with any yellowing leaves near the bottom of the plant.
Be vigilant for fungal diseases, especially Botrytis and Blossom end rot. Adequate ventilation and regular watering will help avoid these conditions. Whitefly and red spider mites can be troublesome. Pesticides are available and an affective biological control is available for both the control of red spider and whitefly.
Personal preferences
Deciding on what varieties of tomatoes to grow in a greenhouse will very much depend on preferences and availability. There are some very good varieties that will produce a heavy crop of medium size, red sweet fruits and there are those that will produce larger but fewer tomatoes, for example Beefsteak tomatoes are exceptionally large.
Also, you have a choice of red, dark red, orange or yellow coloured tomatoes alongside standard and plum shapes. Tomato tastes may vary too from sweet to tangy. Generally, the smaller the tomato, the sweeter it will taste, whereas larger tomatoes tend to be much juicier.
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I have grown many many different varieties of tomatoes over the years, and for me the sweetest cherry tomato is Sungold. I would recommend everyone to give it a try.
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I have grown many many different varieties of tomatoes over the years, and for me the sweetest cherry tomato is Sungold.
I would recommend everyone to give it a try.