Gardening Advice: Tulip Offspring
Q: For three years I’ve planted some large beds with top-grade Dutch tulips. The first spring every one comes up and the sight is breathtaking, but the second season has been disappointing. Why don’t my tulips come back? — Doug Richards, Grand Rapids, MI
A: Since most other spring “Dutch” bulbs do come back so dependably, it seems only reasonable to expect the same from tulips. Daffs, crocuses and grape hyacinths grow like weeds. But tulips, particularly the big bedding types that you probably are using, are great only the first year. Even in Holland, where the weather is almost ideal for them, bedding tulips are treated as annuals to be enjoyed in spring and planted anew every fall. Here’s why: The tulip bulb we plant in fall makes its flowers and then is used up by next summer. In its place new “daughter” bulbs arise from the base of the old bulb,and the daughters do not necessarily get bigger than the parent. In a garden they almost never do because the jumbo bulbs sold to gardeners are really the end of the line — grown with great skill under ideal conditions and to a size that is about as big as a tulip bulb can get. To grow bulbs to sell, Dutch tulip producers plant medium and small bulbs (not big ones) and turn them into a crop of jumbos,which they send to market, and a crop of medium and small ones,which they replant to develop into next year’s jumbos. The largest bulbs, which are what we plant, produce several smaller bulbs, so their second-season flower show is inevitably smaller.
American spring weather in most regions is fine for encouraging tulip flowers, but terrible for sustaining bulbs in the ground. Tulip bulbs need cool weather for a couple of months after bloom. But most of the country gets hot fast in spring and stays that way all summer. Worse, once hot weather arrives and tulips go dormant, the soil should stay very dry. During rainy summers or in beds that are irrigated either for flowers or nearby lawns, many of the bulbs will rot. So in most of America the bulbs won’t have a chance to grow very big, and after going dormant, they will decay in wet ground. Michigan’s climate is among the best for tulips in North America. Summer moisture is a bigger threat there than hot spring weather. If you are replanting a tulip bed with summer annuals (which need to be watered), you should dig the bulbs when the foliage dies back to keep bulbs from rotting. In fall replant those bulbs in rows in a cutting garden (or wherever you are not so fussy about flower size) and pick blooms next spring. For continued spring display in your formal beds, you have several options. The best is probably to just bite the bullet and replant with a fresh crop of top-grade tulip bulbs every year. This is usually no more expensive than planting any other sort of annual flower. You might try switching to Darwin hybrid tulips, which are better able to form large daughter bulbs in our warm springs. That way you might get a good show for two or three years. Plant the bulbs very deep — dig out the bed 8 inches deep when you set them — and if you replant the tulip beds for summer, choose annual flowers that need very little water.