Snail Eating Turtles in a Permaculture Garden, California Central Coast

I live in Santa Cruz county, any my garden is infested with slugs and snails. I don't have the time to pick every single one by hand, and I can't seem to keep any young plants or seedlings alive. They eat the seed leaves of every sunflower, bean, flower, herb plant that grows in my garden.

I realize the problem I have is a predator deficiency, but I am in an urban setting and my HOA doesn't allow chickens or ducks. I am completely against slug-o. I have been trying several things to deter the snails from entering a perimeter around my seedlings. For instance, I used to get bags of coffee grounds from local shops then spread it all in 6" thick circles around the base of a newly transplanted zucchini plant. I have read about people having success using this method, though I did not share their same success. Recently, I have been saving all of my egg shells, baking them at around 250F until completely dry and the tips are starting to get golden, crushing them roughly into 1/4-1/2" shards, then spreading them in circles around vulnerable seedlings. I have read snails don't like the feeling of moving over these 'shards-of-glass' and will avoid them if able. Again, I didn't get similar results. I believe I came up with an effective natural way to manage my snail population.

Some species of turtles eat snails and slugs, along with plants in your garden. I was wondering if others use turtles as a predator. What type of plants should I keep a turtle away from? It seems obviouse to me that I shouldn't let them into a bed of lettuce or low flowers, but can I have them around largest plants or shrubs? I have Artichoke plants, jeresulem artichokes, sunflowers, various woody shrubs like microphylla, Cleveland sage, African safe, phygellium, salvia greggi, bush lupine, and a manzanita ground cover, blueberries, goji berry,and I'm planning on planting alfalfa for a nitrogen fixing chop and drop mulch. I also grow herbaceous plants like comfrey, borage, nasturtium, arugula, squash, strawberries, calendula, curly dock, lambs quarters, kale, cilantro (planted 6 plants last weekend, only have 3 left), climbing winter pea, and California poppy. I'd be worried about all of those plants. I wouldn't be worried about them eating my ripening tomatoes because I use the love apple farms method, growing indeterminate varieties and training the vines to grow vertically so the turtles won't be able to reach them.
Which turtle species do you have, and what percentage of their diet is plant matter? Would they eat a large amount of snails and slugs if presented? Why special features do your turtles need? Please link videos and other helpful instructional articles.

Thanks for reading and thanks in advance for any advice.

My experience with the eggshell trick: mash the hell outa them eggshells! Like, with a rolling pin. 1/4" is much too big to be effective.

My (single, short) experience with a tortoise: not very smart. Happy to eat things that would kill it, like pieces of metal, chemical fertilizer... And any flower looked like candy to it, it would trundle along at top speed over the whole lawn for one more dandelion flower. Honestly I would expect a garden to look like a giant salad bar to one.

But! What about using a tortoise-patrolled perimeter around the outside of the garden? I plan to try this with ducks...

Do beer traps work on snails like they do slugs?

Good tip on those egg shells, that would seem to imitate diatomaceous earth?

I've actually been doing some reading on turtles since I first posted. It turns out a box turtles only consume 30% plant material, and 70% animal material such as slugs, snails, and other invertibrets.
I hear your concern about bits of metal and chemicals, and I assure any harmful products are strictly forbidden in my garden.

What do you think about keeping them around only shrubs, and supplement their slug diet with plant material?

Well, even mangled with a rolling pin the result is notably larger than the very small particles in diatomaceous earth, but the idea was always to create unpleasant sharp edges, which would be similar to the affect of diatomaceous earth; the smaller pieces just makes more of such edges, for a given snail-width area. Let me know if it works for you!


Box turtle sounds rather promising; I'd thought you'd need a tortoise for a land-dwelling creature, but apparently that division isn't really along the lines of tortoise=land, turtle=mostly water. Between the various subspecies one will probably be well suited to your climate/environment.

Looks like cats/dogs can be an issue for them, something to watch out for.

Keeping them away from short and high value stuff seems like a good option; you could sow low effort/cost expendables under the shrubs in turtle-patrolled areas as turtle-food, and probably some of them would survive to serve as beneficial attractors, nitrogen fixers, accumulators, etc.

If you go ahead with this, an accelerated go-pro video of your snail-slayers daily grind could be pretty neat!