Since ingestion of rocks/stones might be a sign that your tortoise is craving calcium and other nutrients, it is always a good idea to start by checking that their environment and husbandry (especially diet and nutrient supplements) are proper for their species.
Taking a physical measurement of the temperature gradient within the enclosure and measuring humidity with a hygrometer are a good idea. Making sure the UVB bulb is appropriate for the size of the space and has been changed regularly if they are housed indoors. Even if they are still producing visible light, UVB bulbs have a limited lifespan and need to be changed every 6-12 months, depending upon bulb type. Making sure diet is varied and appropriate for their species of tortoise and supplemented with calcium and multivitamin powder as recommended. Therefore, I am providing a Greek tortoise care (husbandry) reference sheet that I put together. Please review it at your convenience and let me know if you have any questions.
Greek Tortoise (Mediterranean spur-thighed tortoise), Testudo graeca
Life span: 50+ years
Native: Northern Africa, Southwest Asia and Southern Europe
Adult size: 10 inches
Behavior: Greek tortoises make good pets as they are mellow and can become social with people over time but, in general, they prefer not to handled and can bite if they feel threatened.
These tortoises should ideally be housed separately singly since males will fight, especially during the mating season and during courtship males will persistently chase females, sometimes leading to injury. These are active tortoises and are good diggers and foragers though not strong climbers.
Housing: If housed outdoors they need options for sunbathing as well as shaded areas to escape the sun and heat if needed. A large, shallow water pan should be provided and changed daily, or more frequently when soiled. They require heated, dry housing to escape cold temperatures or bad weather. Care must be taken when housed outdoors to protect them from predators (or even people who will sometimes steal them).
When housed indoors, they require UVB lighting, suitable temperature gradient and a sizeable enclosure (3x6 ft/1x2 m at minimum) for proper exercise lined with 4-6 inch deep of natural substrate for digging that should be changed out monthly. Nice options for substrate include pesticide and vermiculite free topsoil mixed with peat moss or coconut fiber. Cypress mulch can be used as a substrate or top dressed on the soil mix to help maintain humidity.
Lighting: Direct sunlight is optimal but if indoors, they require 12 hours per day of UVB lighting along with 12 hour visible light cycle. For indoor tortoises, a 10% (10.0) T5 linear fluorescent bulb mounted in a reflector housing is a good option, though for larger enclosures mercury vapor bulbs, which combine heat, visible light and UVB light can be used. Care should be taken that the basking or mercury vapor bulbs aren’t too close to flammable materials as they get very hot.
Temperature: Greek tortoises require a warm temperature gradient of 75-85F (23.9-29.4C) as well as a hot basking spot, 95-100F (35-37.8C) though they can take slightly warmer temperatures in the summer if provided sufficient shady spots or a cooler zone to retire to. Nighttime temperature of at least 70F (21.1C) is recommended. Tortoises housed outdoors will need a raised, heated shelter if night-time temperatures drop below 65F.
In cooler weather, they require supplemental heating and advise keeping the pen elevated off the ground to prevent chilling. If heating is required at night, use something that does not produce light, such as a ceramic heat emitter. Fully adult, outdoor tortoises (over 3 years old) can be allowed to hibernate if acclimated to outdoor temperatures, when temperatures are consistently below 48F (9C). They should be fasted for 2-3 weeks prior to hibernation to ensure their GI tract is empty during hibernation. However, it is critically important to still provide fresh water every day during this time as they will need to build up hydration and reserves prior to hibernating. Temperatures should not go below 40F (4.5C) during hibernation, otherwise a hibernating tortoise might die from exposure. It is not recommended to hibernate indoor only tortoises unless you are a highly experienced tortoise keeper. Hibernation is not required for proper health and improper care or temperatures can lead to serious health issues.
Humidity: Humidity of the enclosure should be 40-60% which might require periodic misting of the warmer side of the enclosure. Avoid moistening substrate on the cool side of an indoor enclosure as damp and cool conditions can predispose respiratory or skin infections.
Diet: High fiber diet of leafy weeds plus timothy grass and orchard grass hay. Avoid alfalfa hay as it has too much protein. Weeds might include clover, dandelions, spineless Opuntia cactus pads, broad and narrow leaf plantain weeds, honeysuckle, white deadnettle, yellow archangel, chickweed, hawkbit, sow or globe thistle, and others. Other vegetables should include dark, leafy greens such as dandelion, watercress, escarole, clover, globe artichokes as well as edible flowers such as hibiscus, geraniums, evening primrose, African violet, marigold or nasturtium. Small amounts of other beta carotene rich vegetables such as carrot, bell peppers, squash can be added for variety.
Limit amounts of cruciferous vegetables, such as broccoli, kale, cabbage, bok choy or brussel sprouts as they contain goiterogens which can interfere with thyroid function.
Also avoid vegetables high in oxalate such as spinach, swiss chard, raspberries, rhubarb, parsley, beet greens as these can interfere with calcium metabolism.
Lettuce is not very nutrient rich so should be avoided in favor of dark, leafy greens and hays, grasses and tortoise safe weeds.
A wonderful online resource for searching tortoise safe plants, fruits and vegetables is maintained by The Tortoise Table at:
Supplements: If only eating foraged vegetation, provide a source of calcium such as cuttlebone, calcium block or eggshells to supplement dietary calcium at least two times weekly, if not more often. If feeding prepared salad, lightly dust the salad with calcium only powder three times per week for adults (4-5 times per week for young tortoises) and with reptile multivitamin (calcium, vitamin A and D3) twice weekly.