Getting bulbs to come back year after year can be difficult unless you choose bulbs that promise many happy returns.
Spring-flowering bulbs are pretty darn easy to grow: You plant them in the fall, they bloom in the spring.
But when it comes to longevity, some bulbs are better than others. There are bulbs that return reliably year after year, multiply nicely and don't require much extra attention. Here are some of my favorites:
Some minor bulbs (so called because of their smaller size, not their value in the garden) top my list of best-bet bulbs.
Siberian squill (Scilla siberica), a 6-inch-tall bulb with pure blue flowers, and striped squill (Puschkinia scilloides), which has blue and white striped flowers, are great choices because they are Zone 3 hardy and multiply readily from bulb increase and self-seeding. The narrow leaves of these squills mature and fade quickly, which makes them perfect for planting right in your lawn.
Crocus (both the small-flowered snow crocus and large-flowered types), glory-of-the-snow (Chionodoxa) and the late-spring-blooming grape hyacinths (Muscari) also return reliably for many years, though they don't spread quite as liberally as the squills.
Among the larger bulbs, narcissus provides the best display from year to year and many are hardy to Zone 3 or 4. Another plus: Squirrels and small rodents don't go after narcissus bulbs the way they do tulips.
Narcissus does have a few drawbacks. The foliage hangs around for a while, usually until the end of June or later. And if you want the flowers to come back, you need to leave the foliage in place until it withers. And while narcissus can be grown in one place for years, it should be divided when overcrowding starts to reduce the flowering.
Though they are much-loved, hyacinths and large-flowered tulips are among the shortest-lived bulbs. They may come back for a few years, but they're rarely as long-lasting as narcissus. However, the smaller flowered tulips -- such as Emperor, Kaufmanniana and species tulips -- have a better chance of returning for many years, especially when planted in very well-drained sites such as rock gardens.
BUY GOOD STUFF
Bulbs should be plump and firm. Discard shriveled, soft or damaged bulbs. A few flecks of mold from storage isn't a problem, but a lot of mold or rot means the bulbs are no good.
GET THEM PLANTED
Get bulbs planted as soon as possible after purchasing or receiving them. The bulbs need time to develop roots before the ground starts freezing. Narcissus needs more time than other bulbs, so get them planted by the end of September. Plant minor bulbs (crocus, squill, grape hyacinth, etc.) by mid-October. Tulips tolerate later planting than other bulbs, but it's still good to get them in the ground by late October.
THE RIGHT DEPTH
Minor bulbs (snowdrops, crocus, squill, grape hyacinth) should be planted 4 to 5 inches deep, while larger bulbs such as narcissus, tulips and hyacinths should be 6 to 8 inches deep.
After planting, thoroughly water the area. Continue watering as needed to keep soil moist but not soggy until the ground starts to freeze.
Even hardy bulbs benefit from some winter mulch, especially the first year they're planted. Once the ground has frozen, apply 4 or more inches of loose, dry straw.
LEAVE THE LEAVES
After the bulbs have bloomed in the spring, always let the foliage mature and die back on its own. The foliage has a short period to do its job of making food energy for the bulb. Cutting off green leaves will definitely hurt the bulb.
Nancy Rose is a horticulturist with the University of Minnesota Extension. To ask her a gardening question, call 612-673-9073 and leave a message. She will answer questions in this column only.