I have a post on substrates already called Russian Tortoise Substrates, but I will cover this again since it’s a popular topic and a question I am frequently asked.
It took me a long time to find the right substrate or bedding that worked for keeping tortoises inside my house. Keeping enclosures in my living room meant spot cleaning 2 times per day and changing the substrate every 2 weeks +/-, provided there were no smells and the substrate was clean. What I found that minimizes smells, does not mold easily when wet, does not attract bugs, and only costs a few bucks per bag is undyed cypress mulch.
I get my mulch from a smaller local hardware store – Ace Hardware. Larger hardware stores like Home Depot and Lowes also sell cypress mulch, but not near me that I have found. One bag is measured in 2 cubic feet and the bag fills a 5-gal bucket. I store the mulch in sealed buckets to keep it clean and bug free. The cut of the cypress mulch I am currently using is shredded rather than small chips.
If you cannot find cypress mulch, what you want to look for is undyed fine wood chips, often called playground mulch. It is best to buy undyed or uncolored mulch. When colored mulch gets wet, the dye will come off onto your tortoise. A turtle and tortoise’s shell are permeable and will absorb that dye – that’s not good.
Large barks chips are just too big to use for a good bedding. Organic plant-based mulches like straw or compost can mold and straw does not absorb liquid well.
Personally, I am not a fan of the smell of pine mulch, especially when it gets wet, but it does resist mold and bugs. Fir bark (as used in Repti Bark) is also a good option, but I think it smells like just like pine.
Another option is coconut husk fiber or coir. I found it to be very messy and because it retains moisture, it attracted bugs, yuck. Torts will sometimes eat the fibers. This isn’t a big deal as it will pass through their intestines, but there are better substrate options and why have them consume something that has no nutritional value.
I no longer keep tortoises in my living room, but I still use cypress mulch for tortoise bedding in my dedicated reptile room to avoid smells, mold, and bugs. Notably, I use cypress for all the species I keep and this works for most tortoise species.
Happy tortoise keeping!
The Tortoise Keeper 