Greetings. Tortoises by nature are opportunistic grazers. In the wild, they honker down, they walk in search of food, eat, graze, eat some more, walk some more in search of more food & water or eventually to mate. Thats what your Russian tort is programmed to do.
Make sure you have a nice large enclosure. Most here on TFO will say 8 feet by 4 feet is a minimum. Provide a good handful of food the size (or more) of your tort’s shell. Vary the things you feed. If it eats it all, add more and more until you determine how much they eat in a given day.
I really don’t think that you can OVERFEED good stuff, you could overfeed bad stuff. So, feed inly good recommended Russian food stuffs.
Russian tortoises need broadleaf weeds. You will need to learn about the weeds near you and which ones are okay to feed or not. Pics can be posted here on the forum in the "Plant ID" section, or you can take samples to a local nursery. Look for dandelion, sow thistle, mallow, filaree, hawksbit, and many more. If you are not 100% sure that your source is free of pesticides and other chemicals, don't feed anything from there.
You can grow your own food too. Here is one of my favorites: http://www.tortoisesupply.com/TestudoMix
I also get lots of seeds here: http://www.groworganic.com
If you must use grocery store foods I like to favor spring mix, endive and escarole heavily. Also add in carrot tops, cilantro, mustard, turnip and collard greens, and lots of other leafy greens.
It is a good idea to add a product called "Salad Style" to grocery store greens to add some fiber: http://www.tortoisesupply.com/salad-style-food-topper/
This is a new food topper and I like it a lot so far: http://www.tortoisesupply.com/HerbalHay
You can also feed them grape, mulberry and hibiscus leaves, tender young spineless opuntia cactus pads, Mazuri tortoise chow and ZooMed Grassland tortoise food. Alternating and mixing up any of these foods will give your russian a good diet and meet its nutritional needs.
I chose the title of this care sheet very carefully. Are there other ways to raise babies and care for adults? Yes. Yes there are, but those ways are not as good. What follows is the BEST way, according to 30 years of research and experimentation with hundreds of babies of many species. What is...