Hydrangeas are generally easy and reliable plants with little attention needed. They will grow in sun or in partial shade from trees, and are ideal for a north-facing bed that gets little sun and for open woodland type sites. This is because they do like moisture and shaded beds tend to keep more damp, unless right under trees.
They do well in a wide range of soils except shallow, chalky soils and dry soils; they are always helped by having plenty of humus (compost, manure, etc) dug in and used as a mulch.
The soil affects the colour of the flowers more than any other flower we grow. Many varieties will produce the most fabulous blue shades on acid soils, because of the iron.
but on neutral and alkaline soils they are much pinker; the darker ones are more red-purple than blue, and this is where the red varieties do best. The best way to get them blue is to use an iron-rich (chelated iron) liquid fertilizer every 7-14 days, and especially when the flowers are developing.
Hydrangeas do well in pots and tubs. The more compact (serrata) varieties are good, and the Teller varieties were specially bred for the pot-plant trade. Use a mixture of compost and soil (acid, sandy if you want them blue).
Composted bark and Perlite are also useful ingredients, and it is well worth adding some water-retaining granules, as sold for hanging baskets. Remember to water regularly and either liquid feed regularly or add slow-release fertiliser pellets in Spring.