Corn snakes on the market today are antecedents of animals gathered from all over the natural range. Locality in reptiles can produce great variations in sizes, some specimens will reach a whopping 6ft while others will never exceed 3.5ft. This mean that a mix of animals from different locations ultimately means a mix of sizes further down the line. The locality of a corn snake can also effect the egg clutch and neonate sizes, for example corns bred from north eastern Florida will produce high numbers of eggs; this ultimately leads to individual neonates being of smaller size at birth. Other corn snakes may lay only 8/9 eggs but the babies will hatch at greater sizes. It goes to say then, that if you can find out the source of origin of your animal it will become easier to predict what size it may grow to.
As babies, corn snakes are capable of converting up to a third of what they eat into growth and body mass. Most babies will double their length in the their first year, and it is possible in some cases that the size required for sexual maturity can be achieved in as little as ten months. I do not recommend that you attempt to achieve this, as over feeding can lead to serious health problems. Most breeders will aim to achieve the minimal breeding size of 3ft in eighteen to twenty months. This is much safer. The rate of growth in young corn will not determine how large it will get when it’s fully grown; these factors are set in genetic stone and cannot be changed.
Adulthood in corn snakes is entirely down to size. If you plan to breed your corn, follow the rule of three; three years of age, three feet in length and at least 300 grams in weight. This is widely followed for best results. Reproduction in females of less than three feet puts extreme strain on their bodies due to dehydration and weight loss.
If you have a male corn snake, expect him to grow longer and heavier than a female might. The biggest recorded males have hit the six feet mark and weighed in at around 1000g. However, most corns stay at around four to five feet. As the snake grows, it will shed its skin. This may occur up to ten times during the first year, given that food is readily available. As the snake gets older shedding and growth will slow, and you can expect your snake to be fully grown after about five years. Be aware though, after this point when growth seems to slow or stop completely an adult corn snake will gradually gain weight. Feeding should be reduced as you now only need to maintain your animal, not grow it. Any sudden decreases in weight should be consulted by a veterinarian.