Is it ok to use seashells around a jacaranda in a landscape ring ?

Question

The old tree was killed (we think) by lawn service men scouring the trunk with string trimmers. I put a ring of concrete landscaping blocks around it. Wife thought that seashells would deter weeds and look nice. I put them but now I’m wondering if they might hurt the tree somehow. Any ideas?

Answer 1

They won't hurt the tree, but they won't really keep weeds out either. As the shells degrade, they slowly leach calcium into the soil which will raise the pH of the soil.

https://www.gardeningknowhow.com/ornamental/trees/jacaranda/jacaranda-tree-information.htm