Getting the Most from Perennial Tulips
To encourage perennial tulips to bloom again in future years, we recommend that you do the following:
Fertilize the bulbs when the foliage pushes through the soil in early spring. Don’t overdo it. A light scattering of a low-nitrogen fertilizer, preferably organic, is enough.
Remove the spent flowers as soon as the bulbs finish blooming. Snapping off the top 3 inches of the flower stem prevents seed formation and focuses energy instead on bulb growth.
Allow the foliage to yellow and wither completely before you remove it.
Avoid summer irrigation. Tulips prefer to be dry during their dormancy.