As most gardeners know, tulips bloom best the first year after planting; thereafter, it's often a slow decline until you're eventually left with a sorry-looking patch of green leaves. Some tulips (notably species, Darwin and Triumph types) may continue to bloom season after season, but most cultivated varieties produce fewer and fewer blooms each year. When these bulbs stop producing flowers, they're known as “blind” tulips.
To avoid a disappointing springtime floral display, conventional wisdom recommends lifting and discarding tulip bulbs every two or three years. With hundreds of cultivars now available, it's certainly tempting to treat them as annuals, but these throwaway practices don't help when your favourites suddenly become unavailable. Fortunately, tulips are naturally perennial, and with a modicum of effort and patience, bulbs that have exhausted their capacity to produce flowers can be brought back to floriferous splendour in a couple of years.
Year One (mid-spring): Once your tulips start producing few (or no) flower buds, feed them with a water-soluble fertilizer high in phosphorus (the middle number), such as 15-30-15, every 10 days until the foliage begins to turn yellow and wither. Never bind or braid the leaves, as this interferes with the bulbs' ability to store food for the following year.