Answer: The answer to your question depends partly on the results of soil tests and partly on what you can get locally for the most reasonable price. Either sandy or clay soil is always improved by the addition of copious amounts of organic matter such as compost, aged stable manure and bedding, rotted leaves, and so on. A twelve inch deep layer of such material worked into the soil is not too much. Each year you would add more to "feed the soil" and the use of a natural mulch such as wood chips will also help since it degrades over time. Eventually you will end up with a nice soil, but it is an ongoing process to keep it in good condition. Of the choices you listed, my personal preference would probably be the bark, but you would need to take into account its affect on pH as well as the soil structure. The reason I say this is that the rhododendrons and azaleas must have an acid soil, otherwise they will die. Many perennials will tolerate a moderately acid to neutral soil and impatiens do best in a soil closer to neutral. Your County Extension (for the Ocean City area) should be able to help you with the soil tests and interpreting the results, and may be able to suggest some good locally available materials to use as amendments.
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