Puppy keeps eating things he shouldn’t in the backyard.

We have a small backyard which is mostly covered in tiles in the middle, but has regular soil along the borders for plants and bushes, with decorative bark on top. Our pup has only ever been allowed in a small part of the backyard to go potty. We sometimes went beyond the fence to play, but he could never be left unsupervised because of his mischief.

Now that he is 9 months old and spring is coming, I would love for him to be able to go and play on his own in the backyard. How do I go about this?

I know dogs need to be dogs and I don't mind the digging, but he has been throwing up twice since we gave him supervised access a couple of days ago. Every time he ends up eating pieces of bark or digging for old roots/branches/debris and eating those when we aren't quick enough to remove it from his mouth. I am planning to remove the bark, but I was wondering how/if we can ever get to the point where he doesn't eat hazardous stuff without me having to strip the whole garden?