University of Missouri Extension
Story source: David H. Trinklein, 573-882-9631
COLUMBIA, Mo. – Right after daffodils, tulips and hyacinths have spent their last flower, many homeowners mow the plants down. That’s a bad idea if you want them to flower year after year.
Spring-flowering bulbs need to photosynthesize and produce food in order to enlarge the bulb and set the stage for next year. To do that you need leaves.
“The plants are collecting the groceries for next year’s flower,” said David Trinklein, horticulture specialist for University of Missouri Extension. “The longer we can encourage spring-flowering bulbs to photosynthesize, the better the flowering performance will be next year.”
Some homeowners don’t mow them down but tie them up into little columns.
“You might as well cut them off because only the outer leaves will get sun and the light will be at a very poor angle. Therefore, photosynthesis will be minimal at best,” Trinklein said.
The foliage of spring-flowering bulbs eventually will turn yellow and die back naturally, Trinklein said. These are cool-season plants, so they’ll disappear from the landscape when summer heat arrives. That’s usually late June, if not before. Once the foliage has died back, it can be removed and discarded without harming the bulb.
Rather than cutting them down or tying them up, this is a good time to give them some fertilizer. Trinklein said organic fertilizers, like bone meal, are good choices for bulbs. “They break down slowly and release their nutrients over time. That reduces the risk of ‘burning’ plant roots from excessive fertilizer.”
“Most organic fertilizers are fairly low in nitrogen, which is important since too much nitrogen tends to promote bulb rot,” Trinklein added.
If you’d rather use an inorganic form of fertilizer, Trinklein says a fertilizer grade of 5-10-5 would work. It’s relatively low in nitrogen, very high in phosphorus and has a bit of potassium. Just sprinkle it lightly around the base of the plant. Avoid getting any of the inorganic form on the leaves because it can cause salt burns.
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 said.
Don’t forget about water. Both during and after flowering, bulbs need plenty of moisture to grow. If rain is scarce, water plants as long as the leaves are alive, he said.
Sometimes, after years of growing in the same spot, the flowers start to decline. This happens because the clump of bulbs becomes too large and the bulbs compete with each other for water, sunlight and nutrients, Trinklein said.
When this happens, rejuvenate the bulb clump by dividing it. But wait until the fall to divide or relocate bulbs. Since these plants are busy storing groceries for next year, spring is a bad time to shock the plants with dividing and replanting. Any time you move a plant, roots are destroyed and lost. Right now the bulbs need all their roots to take up water and nutrients so the leaves can manufacture food for next year’s bloom. Trinklein suggests marking where the bulbs are so you can find them in the fall.
If you must transplant them in the spring, do so with great care.
“Try to remove as much soil as you can around the clump of bulbs,” Trinklein said. “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, but at least they’ll be in a new location, Trinklein said.
For more information, see the MU Extension publication “Spring Flowering Bulbs: Daffodils” (G6610), available at http://extension.missouri.edu/p/G6610.
Photo available for this release:
Cutline: Remove the spent flowers but allow the foliage to die-back naturally
Credit: Public domain image.