Bumblebees are having a terrible time. Their habitats are disappearing and as a consequence the population is in steep decline. Bumble bees nests are one way of helping.
Locate the nest on the ground in a sheltered position in dappled sunlight. Under a hedge or adjacent to a wall is ideal.
To create a nest, make a disk from corrugated cardboard or wire mesh and place a couple of handfuls of dry nesting material on it. Straw, hay or untreated cotton is fine. A shallow dish of sugared water is also helpful, as is a stone near the entrance hole to act as a landing platform.
In early spring you may see large queen bumble bees carrying eggs, seeking a suitable nest site. It is possible to carefully capture these queens and introduce them to the nest. Leave her inside with the sugared water for a day, blocking the hole with some paper. If she likes it, she will start the laying process. Good luck!