Answer: Rhubarb prefers a rich, organic, evenly moist yet well drained soil. Since these are long-lived plants, it is best to apply a generous layer of compost annually to replenish the soil and to use an organic mulch that will break down and feed the soil over time. In addition, an application of an all-purpose complete fertilizer such as a granular 10-10-10 or 5-10-10 might also be used -- follow label instructions. During the growing season, make sure the plant receives adequate moisture to support its quick and lush growth. While bone meal would not be harmful, I think you would probably achieve better results adding some additional nitrogen as well and that would be included in the complete fertilizers. Ideally, you would run some basic soil tests to determine what is needed and apply only the nutrients indicated by the test results. Your county extension should be able to help you with the tests and interpreting the results if you want to be more precise.
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