Fertilize tulips at planting to encourage rebloom

By Marianne C. Ophardt, Special to the Tri-City HeraldOctober 26, 2012 

PASCO, Wash. -- One question I'm often asked about is why tulips don't rebloom.

Tulips don't "perennialize" well, coming back year after year like daffodils. Hybrid tulips are not reliable re-bloomers and typically start to decline after the first year of bloom.

Several practices that help encourage re-bloom include planting them where they'll receive full sun, cutting off the flower stalks right after the bloom fades and not trimming back the leaves until they turn yellow.

If you're trying to encourage re-bloom of tulips, fertilization at planting will help encourage root and plant growth needed for bulb growth next spring. Before planting, mix bulb fertilizer into the soil. Work this in to a depth just a little deeper than you will be planting your bulbs. Adding some organic matter to the soil at the same time also is advisable.

In the spring, fertilize again as soon as the plants first start to emerge from the soil being careful to keep the fertilizer off the plants.

However, even if you do all this, it's likely the tulips will decline after a few years. This is because tulips are native to the mountainous areas of central Asia characterized by rocky soils, cool wet springs and hot dry summers. In their native climate, tulips sit dormant during the summer in dry soils and start growing new roots when fall rains begin.

While our climate is somewhat similar, bulbs don't stay dry during the summer when they're planted in our gardens. Moist to wet soil conditions can cause bulbs to split into smaller "daughter" bulbs that aren't large enough to bloom the following year.

Peter Chan, renown Portland gardening expert, recommended planting bulbs in wire baskets in the ground and then digging up the bulbs and baskets every spring. That way, the bulbs could be stored during the summer and replanted in the fall. Digging up your bulbs every spring is labor intensive, but it can help you lengthen the blooming life of your tulips.

Lee Valley Tools (leevalley.com) carries open plastic bulb baskets that are used for storing bulbs during the summer and for planting bulbs in the soil. Planting tulips in the baskets makes it easier to locate and remove the bulbs in early summer. The stacking baskets allow for good air circulation and compact bulb storage.

Because most gardeners won't go to the trouble of digging up tulips each spring, bulb researchers have been evaluating tulip varieties for their ability to come back year after year. They have been able to identify some varieties that have less of a tendency to split and a greater tendency to re-bloom over a longer span of time than just a year or two.

In trying to find more reliable re-blooming tulips, the researchers have also discovered that by growing the bulbs in production fields for one year longer than the normal six years, they have extra large bulbs. These larger, seven-year bulbs are more likely to re-bloom in the garden.

These "perennial" tulips are available from a variety of different bulb companies. If they're a little more expensive, they're probably worth it because you won't have to replant your tulips as often. However, the tulips will eventually decline.

So if you prefer not having to replant your spring bulbs often or dig them up every year, stick with daffodils.

* Marianne C. Ophardt is a horticulturist for Washington State University Benton County Extension.

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