Answer: Four inches is very low for most annuals, but here are some suggestions. For a sunny spot you might try sweet alyssum, portulaca, or nierembergia. For partial shade you might try sweet alyssum, lobelia, or the (5") foliage plant called hypoestes. For shade you might try the hypoestes, or perhaps a smaller form of impatiens which, although it exceeds four inches would provide you with blooms all season.
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