Answer: You can use any organic material for mulching beneath your rose bushes. I like shredded bark, but bark chips or nuggets work well, too. The whole point in mulching beneath roses is to help conserve moisture and suppress weeds so anything that will go well with the theme of your garden will be fine as mulch for your roses.
Eggshells are 93% calcium carbonate. Calcium is an essential plant nutrient which plays a fundamental part in cell manufacture and growth. Most roots must have some calcium at the growing tips. Plant growth removes large quantities of calcium from the soil, and calcium must be replenished, so this is an ideal way to recycle your eggshells. The eggshells should be crushed or ground into a powder form so they can easily release their nutrients.
Q&A Library Searching Tips