Boulders for raised beds?
I'm not diagnosed yet, but my rheumatologist feels I may have a form of spinal arthritis that could eventually lead to fusion of the spine. Currently I have fairly decent range of motion (though I haven't been able to touch my toes since before high school) but I deal with varying levels of pain and fatigue. Also my knees cannot handle much kneeling. I'm thinking sitting may be the best position for gardening. I'm here looking for some input though. Vegetable gardening is my main concern as I can get my husband to help with the landscaping. He's just not enthusiastic enough to keep it up as much as a vegetable garden would need.
We recently moved onto our dream property, it's mostly lush Pacific Northwest forest except the especially rocky area where we placed the house. We do have great Southern exposure in our natural clearing. Even nature didn't want to grow big trees in these rocks! Rather than fighting the soil (or lack of), we are building raised beds. We plan to grow old here (I'm 31 years old), so all plans are long-term plans. Adding in the "aging-in-place" plan and the possible spinal arthritis, I'm hoping come up with a long-lasting gardening solution that will remain usable by me for many, many years.
I really don't want to rebuild wood planter boxes every 5-10 years! And I don't want to use anything that may leach into the soil like plastics, composite-lumber or concrete. So we are considering building raised beds with 12" boulders, just one stone high with no mortar between.
The plan is to sit (with a cushion) on the boulder edge for weeding, etc. I've determined I should be able to reach (without bending) halfway across a three foot bed (interior dimensions). But I wonder if I'm on the right track. I really don't have a good grasp of how spinal fusion may limit me. I'm hoping someone with some experience can critique my plan. Is this likely to still be accessible assuming the worst and I fused fairly severely? Should I plan for the eventual possibility of a raised-off-the-ground type of a bed that I can sit under, like a table at a chair? If so I may not go with something quite as permanant as the boulders for now. Should I create narrower beds than I can handle now, or is that a measurement that is likely to stay stable?
I cannot find any information about anyone doing vegetable gardening with boulder walls. Is there a reason nobody seems to be doing it? Is there something I have forgotton to think about? Am I going to have to make adjustments for the thermal mass of the boulders? Will the boulders help warm the soil in the spring or will they block the heat and keep the beds cooler? Am I in danger of "cooking" my plants in the heat of the summer? Here in the Pacific Northwest we are used to worrying about not enough drainage; but will I get too much drainage with boulder walls that are essentially open every 12" (with no mortar between stones)? If so I can adjust my soil mix inside for better water retention, correct?
I guess I branched into two distinct veins of questions. There's the possible spinal fusion and the ergonomics of a 12" high raised beds with wide sides for sitting. The other relates to the boulders themselves affecting the soil temperature etc. (would the latter be better on another forum?). Thank you for all your input!