Tortoise Diet

To provide your tortoise with the correct diet you must, first of all, know what species of tortoise you keep and be aware of its specific dietary requirements, as they may differ from species to species.

How Often Should You Feed Your Tortoise?

Feed hatchlings and young tortoises daily or divide the daily portion in two and feed morning and afternoon.

Adult tortoises can be fed daily or you may choose to omit to feed for one day a week.

How Much Should You Feed Your Tortoise

In the wild, many species of tortoise live in hot, dry areas where food is scarce and they have to walk long distances to find enough to eat.  In captivity, we often present our tortoises with large quantities of food, and it is easy for them to overeat, which can lead to shell growth deformities and other health problems.
 
There are several loose guidelines on how much to feed (all they can eat in 20 minutes once a day; enough leaves and flowers to make a little blanket to cover their shell), but the best method is to be aware of the growth pattern of your species of tortoise and monitor his growth, and this will lead you to settle on how much is appropriate to feed him.

For Mediterranean species (Hermanns, Graeca, Ibera, Marginated, Horsfield) aim for steady, slow growth, with an average weight gain of between 1g - 3g per month.  This is only an average, and some months your tortoise might gain more and some less.  If, after a suitable period of monitoring, your tortoise seems to be gaining too much or too little weight then you can adjust the amount you feed accordingly.

N.B. The larger species, like Leopard and Sulcata tortoises, normally have different rates of growth at various stages of their development, so the 1g - 3g per month guideline is not appropriate for them.

Variety

Try to offer a wide variety of safe leaves and flowers to your tortoise,
and do your best to give him a varied diet.

In the wild it is estimated that many tortoises (with the exception of Leopards and Sulcatas, who are primarily grass eaters) feed on around 200 different species of plants in any one year.  This means that no one plant makes up the majority of a tortoise's diet (although in the spring, when some plants are in flower, they might comprise the majority of food for a short period of time).  In captivity it is almost impossible for us to replicate such a wide variety of food, but it is important that we try our best to ensure that no one plant makes up the majority of a tortoise's diet for an extended period of time. 

One thing to be aware of is that some plants are safe to feed only in moderation or sparingly
because they contain anti-nutritional properties

For example, many plants contain oxalic acid, which can bind with calcium and prevent the tortoise from absorbing that and utilising it for the healthy growth of bone and shell. These plants are often safe to feed in small amounts, but it would not be wise to feed five different plants which are all high in oxalic acid at the same meal.  Goitrogens are another case in point.  Plants of the Brassicaceae (Cabbage) family are high in goitrogens, which can interfere with thyroid activity and possibly damage the liver and kidney.  Small amounts of plants with goitrogens will do no harm to your tortoise, but to feed only one Brassica plant, or a variety of plants that are high in goitrogens at every meal would not be advised.

Natural Graze and Sunshine

Whenever possible, if it is warm enough, your tortoise should be allowed outside to graze naturally and get the benefit of natural sunlight for the synthesis of vitamin D.  Please ensure that there are no poisonous plants within the tortoise's reach. 

If your tortoise is housed indoors then it must be provided with UVB from an artificial source, as UVB is not transmitted through glass; so placing your tortoise table under a window will not suffice.

A mineral and vitamin supplement can be added to the food daily.

Fruit

Tortoises love the sweetness of fruits, but the digestive system in most tortoises is not geared towards digesting fruit and offering it should be limited.

Species such as Red and Yellow-footed tortoises can tolerate fruit and therefore it can make up a small part of their daily diet.

Salad Items

Salad items, such as lettuces, have little nutritional value and contain little fibre.  As a result, they pass through the tortoise's digestive system quickly, often giving rise to loose faeces.  Salad items should not be offered on a regular basis but can be used to supplement other food when overwintering your tortoise when healthier foods are less available.

Vegetables

Vegetables such as Peas and Beans are high in protein and phytic acid should be avoided where possible. 

Root vegetables such as Carrots or Parsnips are high in carbohydrates and should be limited and preferably not fed at all.  Dark green leafy vegetables such as Cabbage are often recommended for tortoises when flowering plants and weeds are not available but remember they are high in goitrogens and should not be fed exclusively.  Kale is one of the better vegetables, as it has a high iodine content which counteracts some of the effects of the goitrogens and it also has a better calcium-phosphorus ratio.

Water

Fresh drinking water should always be available.

Most tortoises are strict herbivores, but some species such as Red and Yellow-footed tortoises, Box Turtles and aquatic turtles are omnivorous and earthworms etc. may be added to the diet.