Q&A with Sandy Feather: Fertilize daffodils in fall or spring

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Q: What is the best time to fertilize established daffodils? I have read conflicting advice; some suggest fertilizing in the spring, while others say fall. What is the best fertilizer to use?

A: Daffodils and other bulbs put on significant root growth in the fall, so it is a good to time fertilize them. Root development continues until soil temperatures fall below 40 degrees and then resumes in the spring as soil temperatures warm.

However, in the spring, more energy is expended producing foliage and flowers than root development. If you forget, or run out of time to fertilize bulbs in the fall, spring is the second best time. For established bulbs, rake back the mulch and broadcast a granular fertilizer across the soil surface. Replace the mulch to protect the soil surface from erosion and nutrient loss to runoff. The fertilizer will be carried down into the soil with rain, snow melt and winter's freeze-thaw cycles.

If you fertilize in the fall, a slow-release source of nutrients is best, such as an organic fertilizer or an organic-based fertilizer. Whatever slow-release fertilizer you choose, be sure it is low in nitrogen and higher in phosphorous and potash. All fertilizers are labeled with three numbers that indicate the percentage of those nutrients. They are always listed in the same order: nitrogen-phosphorous-potash.

Brent and Becky Heath from Brent and Becky's Bulbs recommend a fertilizer called Bulb Mate, with an analysis of 5-10-12. However, if you fertilize in the spring, a more water-soluble source of nutrients is a better choice, such as 5-10-10.

Organic and slow-release fertilizers have to be broken down into a form that the plants can use, usually by microbial activity. When you fertilize in the spring, slow-release fertilizers may not be broken down in time for the bulbs to use the nutrients before their summer dormancy.

Q: I started a compost pile last summer with grass clippings and plant debris from my flower and vegetable gardens. How can I tell if it is ready to use when I prepare my gardens?

A: Compost that is thoroughly "done" has a fresh earthy smell, and you cannot identify the original components. It has a crumbly, humusy appearance, and its pH, or level of acidity or alkalinity, is close to neutral (7.0).

Actively composting piles generate heat, while finished compost has cooled off to the ambient air temperature or just slightly higher. A finished compost pile should be about half its original size. If you want to test it, sift a little compost and sow lettuce seed in it. If the lettuce germinates and grows, it is probably fine to use as a soil amendment.

If you have turned the pile regularly, maintained proper moisture levels and paid some attention to the carbon-to-nitrogen ratio, you can have finished compost in four to six months. If you do not compost as actively, it can take a year or so for the compost to finish.

Unfinished compost can tie up the available nitrogen in the soil, which causes nitrogen deficiency in the plants growing here. Avoid the problem by making sure compost is finished before tilling it in, or add some fertilizer that contains nitrogen to make up for the deficiency. One cup of 10-10-10 per three bushels of compost should be sufficient.

Send questions to Sandy Feather by e-mail at slf9@psu.edu or by regular mail c/o Penn State Cooperative Extension, 400 N. Lexington Ave., Pittsburgh 15208.


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