Answer: A layer of gravel can be used as mulch, however it is stressful on your plants because it holds and reflects so much heat during both summer and winter. It also does not help feed the soil the way an organic mulch does as it breaks down over time. I would encourage you to consider changing to an organic mulch for these reasons.
However, if you prefer the gravel, you could use heat tolerant plants such as junipers or barberry in a full sun location. In shade, you could try hostas.
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