Q.Red Lava Rock
I have several weeping cherry trees planted along my property. We have placed garden edging blocks around the base of the tree. We also put top soil and red lava rocks inside the circle the blocks created so my neighbor’s cats will stop using the dirt for a litter box. Will the red lava rock harm my trees? If so, what do you suggest I use to keep the cats out?

Certified GKH Gardening Expert
It should not have any adverse effects on the tree, but whther or not the cat will stay away, who knows. They can be pretty persistent once they've found a regular 'dumping area.' That being said, this article will provide some suggestions that may also help with your problem: https://www.gardeningknowhow.com/plant-problems/pests/animals/cat-repellent.htm