Leave the leaves on flowering bulbs.



Linda Geist
  • Daffodil (narcissus).Kham Tran, CC BY-SA 3.0
    Daffodil (narcissus).Kham Tran, CC BY-SA 3.0

COLUMBIA, Mo. – One of the joys of spring is the emergence and flowering of bulbs such as daffodils, tulips and hyacinths, says University of Missouri Extension horticulturist David Trinklein.

If you want them to keep flowering year after year, don’t mow them down after they have spent their last flower, as many homeowners do. Spring-flowering bulbs need their leaves to manufacture food through photosynthesis so they can enlarge and prepare for flowering the following year, Trinklein says. “The longer we can encourage spring-flowering bulbs to photosynthesize, the better the flowering performance will be next year.”

Don’t tie me down

Some gardeners tie their leaves together into little bundles or columns rather than mowing them off. They do this to make room for other garden plants.

That’s not a good idea. “When tied together, only the outer leaves will receive any sunlight. Therefore, photosynthesis will be minimal at best,” Trinklein said.

Be mellow, they’ll turn yellow

In time, the foliage of spring-flowering bulbs will turn yellow and die back naturally, Trinklein said. Spring-flowering bulbs are cool-season plants, so they'll disappear from the landscape when summer heat arrives. Once the foliage has died back, it can be removed and discarded without adversely affecting the bulb.

Feed me slowly

Rather than cutting them down or tying them up, good time to give them some fertilizer. Trinklein says organic fertilizers are good choices for bulbs. “They break down slowly and release their nutrients over time. Therefore, there is a reduced risk of burning plant roots from excessive fertilizer.”

Additionally, most organic fertilizers are fairly low in nitrogen. “This is important since excessive amounts of nitrogen tend to promote bulb rot,” he said.

If you'd rather use an inorganic fertilizer, Trinklein recommends 5-10-5. It's relatively low in nitrogen, high in phosphorus and has an adequate amount potassium. Sprinkle it lightly around the base of the plant, he says. Avoid getting any on the leaves because it can chemically burn the plant.

Don’t let the bloom loom

After the flowers fade, remove them. “We don't want the plant putting any energy into making seeds. We want that energy put back into the bulb,” Trinklein says.

Both during and after flowering, bulbs need plenty of moisture to make active growth. If rainfall is deficient, water plants as long as their foliage is alive.

Stall the move until fall

After years of growing in the same spot, clumps of bulbs can become too large. The bulbs start to compete with each other for sunlight, water and nutrients, reducing flower production.

When this happens, you can rejuvenate the clump by dividing it. Wait until the fall to divide or relocate them. Any time you move a plant, roots are destroyed and lost. In the spring, bulbs need all their roots to take up water and nutrients so the leaves can manufacture food for next year’s bloom. Since the foliage will die back in summer, Trinklein recommends marking where the bulbs are so you can find them in the fall.

If you must relocate them in the spring, do so with great care.

“Try to remove as much soil as you can around the clump of bulbs,” Trinklein says. “Dig a hole of equal size in the new location and very gently make the transfer.”

You might not have as many blooms next year, Trinklein says, but at least they'll be in a new location.

Photo: https://extension.missouri.edu/media/wysiwyg/Extensiondata/NewsAdmin/Photos/Yellow-Daffodil.jpg
Caption: Daffodil (narcissus). Photo by Kham Tran, shared under a Creative Commons license (CC BY-SA 3.0).

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