CU Herb Society Herb of the Month

Since heavily hybridized tulips tend to perform well the first year and then decline rapidly, they are treated as annuals, with the old bulbs dug up after flowering. Years ago, when labor was cheaper, this practice was affordable and led to gorgeous displays. Now that we're doing it all ourselves, interest in "perennial tulips" has increased.

Long-term tulip performance results from two factors: the choice of variety and gardening practice. In general, the closer a tulip is to the original wild species, the more long-lasting it will be. The terms "botanical tulip" and "species tulip" imply perennial and include both big and small flowers. The big-flowering kinds have three main groups: Greigii, Kaufmanniana and Fosteriana. Varieties with variegated leaves are often extremely attractive even when not in bloom. The small-flowering kinds are essentially still wild, but commercially grown and exquisite.
Kaufmanniana are the earliest flowering of the big botanicals and sometimes have mottled foliage. They are 6-12 inches tall and have flowers that open like a star or water lily. Common varieties are 'Giuseppe Verdi' and 'Stresa.'

Fosteriana tulips sometimes have striped or mottled foliage and tend to be 14-16 inches tall. Common Fosterianas are the various colored 'Emperor'-shaped tulips.
Greigii tulips always have striped or mottled foliage. Some locally available varieties are 'Cape Cod', 'Red Riding Hood', and 'Toronto.' Greigiis tend to vary in height, from 6 to 14 inches.

The small botanical tulips tend to be 2-12 inches tall and are the best for naturalizing. There are at least thirty different species offered in catalogs, and some have named cultivars. They bloom at various times, from early to late.

Tulips will last longer if they are planted deeper, at least 6-8 inches for the three big varieties and about four inches for the small ones. By planting the bigger varieties deeper, the bulbs will multiply less but have bigger blooms. Tulips should also receive at least a few hours of sun daily in the spring and be in a well-drained spot. More sun will assist tulips in being perennial. If the old blossoms are cut off, the plant will put its energy into rebuilding the bulb rather than producing seed. It's also important to allow the foliage to ripen fully before detaching. The foliage is ripe when it has turned brown. Although braided leaves look nice, they probably diminish the bulb's ability to make food for the next season. Some growers recommend applying a bulb or low-nitrogen fertilizer every fall, while others favor spreading a complete fertilizer in early spring, before growth or flowering begins.

In time, each bulb will produce a clump which can then be divided. Wait until the foliage turns brown before digging them up. To reduce damage, use a spading fork rather than a shovel. Pull the clump apart and detach any offsets that are big enough to separate easily. Replant immediately or store in a cool dark place until fall. The offsets may take a year or two to bloom, depending on their size.