There are few other flowering plants that will give you such an impact over so many weeks and even many months as a selection of tender Fuschias. Although these can be moved outside for the summer come autumn they need to be brought under cover and it is then that they prove their worth. With upright varieties for borders and tubs and pendulous ones for hanging baskets you could fill a greenhouse with little else. Of course there are some fairly hardy Fuschias that survive outside, indeed in the south westerly counties there are even Fuschia hedges.
In the colder regions Fuschias get their tops burnt off by the harder winters but they usually recover and come back from the roots. However the hardy varieties are on whole rather limited in colour and range and with a relatively short flowering period are not much valued. The tender Fuschias are far better, and just that, tender, one hard frost and they are lost. But they are not tropical plants and do not enjoy hot conditions. They simply need it frost free to survive and then they continue flowering deep into winter. If your greenhouse glass is spotlessly clean that is- they are not fond of heavy shade and dirty glass will seriously reduce their light and their performance. Beware though too hot, and especially if too dry as well and Fuschias are unhappy and may rapidly succumb to red spider mite.Too dim, damp air and little ventilation and they are in conversely in danger of fuzzy grey mould, botrytis. So aim for frost free but well ventilated, cool and bright and they will be happy.
As to composts; I mix John Innes No 2 or 3 potting compost fifty fifty with peat free Ericaceous, and then add some extra grit as good drainage is crucial. I also recommend seaweed and fish emulsion in their (preferably rain) water weekly. There is a huge range of modern and older hybrids to choose from; so many it is confusing, and some pretty species as well. Not only is there this vast range of flower shapes and colours but their pollen comes in different colours as well- white, yellow, red and even powder blue! But probably Fuschias biggest secret is their berries- these are correctly removed as this encourages more flowers. However for a long time Fuschia societies have had competitions for jelly made from the berries. Some, Phyllis for example, often set loads of hazel-nut sized fruits which make excellent jelly. But for sheer size it has to be the California Dreamer series- they can throw fruits as big as your thumb. Surprisingly some Fuschia berries are quite palatable fresh, it is a shame no-one has introduced a sweeter bigger berried sort- with huge fat fruits ready for Christmas- should make a mint.