Wait until the foliage has died down before digging the bulbs and then store them in flats in a dry garage, shed or attic. When the bulbs are thoroughly dry, remove the older roots from the bulbs, give them a good clean and store them again until September.
Bulbs with a diameter of 2.2 cm or larger will likely flower again the following year. Tulips deteriorate rapidly after three years and should be divided or replaced.
If the space where the tulips are growing is needed for annuals, dig the bulbs while the foliage is still green and the flower has faded. Transplant the bulbs with roots, soil and foliage attached into trenches 15 cm deep. Cover the roots and allow the plants to die down naturally. The bulbs can then be dug up, dried and stored.