Garden Q&A: Dividing may restart blooming of daffodils
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Q. My daffodils have not flowered well for two years. They were here when we bought the house a decade ago, and they always produced a lot of blooms, enough to beautify the yard while giving me plenty to cut for indoors. They do have lots of foliage that appears healthy, just not enough flowers. Can you tell me why they do not bloom more?
A. There are a number of reasons why daffodils fail to bloom. It is encouraging that they have healthy foliage because the problem is likely to be environmental rather than a serious disease or insect problem.
It is very important that you allow the foliage to mature and die back on its own rather then cutting it off or tying it up in any way when the daffodils finish blooming. The foliage is responsible for producing the carbohydrate reserves that nourish the bulb and create next year's flowers and foliage, via the process of photosynthesis. When you cut it off too soon or damage the conductive vessels (xylem and phloem) by tying the foliage into neat bundles, it reduces the length of time it has to undergo photosynthesis and thus the amount of carbohydrates produced and stored for future growth. The longer photosynthesis happens, the more nourishment the bulbs can store, and the better your blooms will be the following year.
Although the dying foliage looks messy, it is vital for the health and performance of all of your bulbs, not just daffodils. Try planting early blooming daffodils with later blooming perennials such as daylilies (Hemerocallis spp.), hostas, Siberian irises (Iris sibirica) or ornamental grasses. The later blooming perennials come up and hide the declining daffodil foliage. Although you should not cut back or damage the foliage in any way until it dies back on its own, it is a good practice to remove the dead flower head, including the ovary behind it. This encourages the plant to put all its energy into nourishing the bulb rather than producing seed. You can just snap it off the flower stalk, and allow the stalk to function as another leaf until it dies back on its own.
Daffodils bloom best in full sun. While they may bloom well in shade the first year they are planted, it interferes with photosynthesis in subsequent years. It is possible that existing trees in your yard have grown over the years and now cast too much shade. While daffodils can co-exist with deciduous trees (those that lose their leaves in winter), it is possible that the trees leaf out early enough to cast dense shade on the foliage, reducing photosynthesis.
Many bulbs quit blooming well when they need to be divided. Daffodils can remain in place for many years without dividing. I often see them blooming in the woods, where they were planted near homesteads that have long since crumbled. No one divides or cares for these daffodils in any special way, yet they bloom year after year. But if yours have been in place for many years, and bloomed well at one time, perhaps it is time to divide them.
The best way to divide daffodils is to dig them up when they have finished blooming and the foliage has died back on its own. The clumps will have large bulbs and smaller offsets. Separate the large bulbs from the offsets and from each other, then replant them immediately. The most desirable bulbs have two flowering points ("noses"), so do not break those up. It will take the smaller offsets two to four years to mature to blooming size, depending on their size.
Finally, you may need to fertilize your daffodils or change the way you fertilize them. Forget liquid fertilizers that have to be applied regularly and use a granular fertilizer with an analysis of 5-10-10 when bulbs have finished blooming. Follow label directions as to how much fertilizer to apply; more is never better. Be sure to brush any fertilizer granules off the foliage to avoid burning. You can repeat this application in mid- or late September. Even though you cannot see the bulbs at this time, they are putting on significant root growth and may benefit from fertilization. Although bone meal is often suggested as a good fertilizer for bulbs, it is best incorporated into the soil at planting time rather then applying it to the soil surface. The phosphorous in bone meal moves very slowly through the soil profile, and it takes time for soil microbes to break it down into a form usable by plants.
First Published December 1, 2012 12:00 am