In commercial greenhouses growers use bumble bees to pollinate their crops. If your plants are outdoors, there should be enough wind and insect activity for pollination.
In the greenhouse, it is a good idea to gently shake the strings or other supports around mid day, or tap the trusses which have flowers open. If the weather is very hot and dry, it may help to water the paths in order to increase the humidity and cool the greenhouse
With cherry varieties you should pick your first ripe tomatoes when they are flowering on the 6th truss; for larger-fruited types you’ll have to wait until the 9th truss flowers. You might get a new truss approximately every ten days, so if you plant in mid May with the first truss in flower, you might expect your first pick sometime in the first half of July for cherry tomatoes and about a month later for larger varieties. In the meantime, buy British-grown tomatoes for the best flavour.
For cherry varieties (apart from Tumbler and other bush varieties) stop the plants (pinch out the growing points) in the first week of September; for all other types stop them in early August. It may help to ripen the remaining fruit if you remove some of the older leaves which are shading them. Don’t do this in very hot conditions as the excessive heat may make the fruit soft.
Did You Know?
2.5 million British native bumblebees pollinate all the tomato crops in the UK. That’s 24 billion wing beats per minute in British tomato greenhouses.