Reptiles · Snakes
Common Garter Snake
Thamnophis sirtalis
Active, diurnal, fish-loving small snakeBeginner
- Lifespan
- 6-10 years
- Size
- 45-130cm (varies)
- Social needs
- Solitary or grouped with care
- Time
- Medium - feed 2-3x weekly
- Cost
- Low
- Diet
- Carnivore - fish, worms, rodents
Overview
What is this animal?
- Common garter snakes are small, fast, diurnal snakes that are active and engaging to watch, unlike many shy nocturnal species.
- They are widespread across North America and come in many regional colour forms.
- They have a weak rear-fang saliva that is harmless to humans, and they are semi-aquatic, enjoying water.
- Their daytime activity makes them appealing, though their varied diet and faster metabolism set them apart from rodent-only snakes.
Temperament
- Garter snakes are alert, quick, and curious, often more nervous than rodent-eating colubrids.
- Many musk readily when first handled but settle with regular gentle contact.
- Their daytime activity makes them rewarding to observe.
- They rarely bite, and their mild rear-fang saliva is harmless to most people.
- Handle gently and briefly at first, letting the snake move through your hands rather than restraining it tightly.
A good fit for
- Keepers wanting an active daytime snake
- Those who can provide a varied diet
- Beginners happy with frequent feeding
- People wanting a smaller, engaging species
Common mistakes to avoid
- Goldfish-only diets cause thiamine deficiency
- Faster metabolism needs frequent feeding
- Can be musky and nervous when handled
- Needs good ventilation and a clean water area
Enclosure
Minimum 4,050 cm² of floor (628 sq in) · 90 × 45 × 45 cm
Fine alone or with company. Solitary or grouped with care
- A single adult does well in a 90x45x45cm vivarium with plenty of cover, climbing branches, and a large water area, as they enjoy soaking and swimming.
- Use an absorbent substrate kept clean, since frequent meals mean frequent waste.
- Provide a basking spot of 28-30C and a cooler side around 21-24C, with low-level UVB beneficial for these diurnal baskers.
- Keep humidity moderate and ensure good ventilation to prevent respiratory problems.
Supplies
Setup
- Enclosure
- Heating and thermostat
- Thermometers and hygrometer
- Substrate, hides at both ends, water bowl
Ongoing
- Frozen rodents in the right size for your snake
- Freezer container or bin dedicated to feeder storage
- Long blunt-tipped feeding tongs
- Sealable bags or a thawing tub for warming prey
- Heavy water bowl big enough to soak in
- Digital kitchen scale for tracking weight
- Digital thermometer for checking prey temperature
Safe substrate: Cypress mulch · Aspen shavings · Topsoil and coco fibre mix
Care routine
Daily
- Check temperatures and humidity
- Look the animal over
- Spot-clean waste and uneaten food
Weekly
- Fresh water bowlevery 3 days
- Short handling sessionevery 3 days
- Check every latch and vent
- Watch for a shed cycle
Monthly
- Check for mitesevery 2 weeks
- Feed a thawed prey itemevery 2 weeks
- Weigh-inevery 2 weeks
- Deep-clean the enclosure
- Test thermostats, lamps and guards
Less often
- Refresh the substrateevery 3 months
- Replace the UVB lampevery 6 months
Vet: Annual exam and faecal check — every 12 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
YouTubers
Snake DiscoverySnake care and behaviour explained (run by a reptile shop)Lori TorriniSnake behaviour, enrichment and choice-based handlingReptiles and ResearchEvidence-led husbandry: enclosure size, UVB, thermal gradients, enrichment
Sites
Go deeper
Diet
- Garter snakes have a varied carnivorous diet of fish, earthworms, and rodents.
- Avoid feeding goldfish and other thiaminase-rich fish exclusively, as this causes vitamin B1 deficiency; use thiaminase-free fish or supplement, and offer earthworms and whole prey for balance.
- Their fast metabolism means feeding juveniles two to three times weekly and adults roughly twice weekly.
- A varied diet is essential to long-term health and prevents nutritional deficiencies.
Health
- Garter snakes are prone to vitamin and thiamine deficiencies from poor diets, and to respiratory infections in damp, poorly ventilated setups.
- Frequent feeding makes a clean enclosure especially important to prevent bacterial problems.
- Feed a varied, balanced diet and supplement where needed.
- Maintain good hygiene and ventilation.
- Their shorter lifespan and faster metabolism call for attentive feeding and prompt veterinary care for any lethargy or breathing changes.
Is your enclosure big enough?
Minimum floor area4,050 cm² (628 sq in) of continuous, unbroken floor
As dimensions90 x 45 x 45 cm
CompanyFine alone or with company. Solitary or grouped with care
Is this urgent?
Most snake worry is about feeding, and most feeding worry is misplaced. Check the guide for this species' normal fast before treating a refusal as illness.
Go now
Open-mouth breathing, bubbles at the nostrils, or an audible whistleGo now. Respiratory infection. Snakes have one functional lung and little reserve.
NowCannot right itself, or holds the head and neck in an unnatural twistGo now. Neurological signs are always urgent in a snake.
NowToday
A regurgitated mealDo not offer food again for at least a fortnight. Check the warm-end temperature today, then call if it happens twice. Usually too cold, handled too soon, or a meal too large. Repeated regurgitation is a different and more serious problem.
TodayRetained eyecaps after a shed, or a ring of stuck shed on the tail tipRaise humidity and provide a damp hide. Call if it is not resolved within a day. Almost always humidity that was too low during the blue phase. A constricting ring costs the tail tip.
TodaySoon
Refusing food for longer than is normal for this speciesLog the refusal and check the species guide. For an adult ball python, a fast of about a month is not in itself a cause for concern, and much longer voluntary fasts are documented. Weigh weekly through it. The weight trend, not the calendar, is what tells you whether a fast matters.
Log it firstThis is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
Can a common garter snake eat that?
Reptile diets split hard by species. An insectivore and a grazing tortoise share almost nothing, so check the species guide as well as this list.
The full list
Never (15)
AlcoholNo safe amount at any body weight on this site.
neverAvocadoPersin. Fatal to many reptiles.
neverCaffeineCoffee, tea and energy drinks. Cardiac and neurological toxicity at tiny doses for an animal this size.
neverChocolateTheobromine and caffeine. Small mammals and reptiles cannot clear either.
neverCitrusToo acidic, and it interferes with calcium absorption.
neverDog or cat foodProtein and vitamin D levels formulated for a mammal. In tortoises it causes irreversible kidney and shell damage.
neverFirefliesLucibufagins. A single firefly has killed adult lizards. This is the most dangerous item on any reptile list and it is the one keepers do not know about.
neverFish caught from the wildThiaminase and parasite risk for turtles and aquatic species.
neverGarlicSame allium toxicity as onion, and more concentrated by weight.
neverIceberg lettuceWater with no nutrition. It fills a reptile up in place of food that would have done something.
neverLeekAllium family. Same mechanism as onion and garlic.
neverOnionOrganosulphur compounds damage red blood cells. The whole allium family is out.
neverRhubarbOxalate load high enough to cause acute kidney injury.
neverSalty or seasoned human foodSalt, oil and seasoning. Crisps, chips, seasoned leftovers and processed meat are all out.
neverWild-caught insectsPesticide residue and parasites, and the identification risk. Captive-bred feeders only.
neverRare treats (1)
WaxwormsVery fatty. Useful for a underweight animal or for medicating, addictive otherwise. One or two, rarely.
rare treatOccasional (5)
Bell pepperSafe, low oxalate, and the colour gets a refuser eating. A few small pieces a few times a week.
occasionalButternut squashWell tolerated and a useful source of vitamin A precursors. Small cubes a few times a week.
occasionalKaleGood calcium, mild goitrogen. Rotate it. Twice a week.
occasionalMealwormsHard chitin shell and a poor calcium ratio. Fine as part of a varied feed, poor as the whole diet. A few, alongside better feeders.
occasionalSpinachOxalates bind dietary calcium, which is the last thing a reptile at risk of metabolic bone disease needs. A very small amount, rarely.
occasionalEveryday foods (6)
Black soldier fly larvaeUnusually high in calcium; one of the few feeders that does not need dusting. Several per feed.
everyday foodCollard greensOne of the best staple greens for herbivorous and omnivorous reptiles. Daily.
everyday foodCricketsA standard feeder. Gut-load them for 24 hours before offering, or you are feeding an empty shell. Sized no wider than the space between the animal's eyes.
everyday foodDandelion greensExcellent calcium-to-phosphorus ratio and readily taken. Pick away from sprayed ground. Daily, for herbivorous species.
everyday foodDubia roachesBetter calcium ratio and more meat per insect than crickets, and they cannot climb glass. Sized to the animal.
everyday foodMustard greensGood calcium ratio; rotate with other greens. Several times a week.
everyday foodThat food is not on our list. Reptile diets are narrower than they look — check the species guide, and ask an exotics vet before offering anything unfamiliar.
Dust feeders with a calcium supplement to the schedule in the species guide. A reptile can be eating well and still be starving of calcium.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
For snakes the substrate has to hold the right humidity for the shed, and let the animal get fully under it.
Safe
Cypress mulchHolds humidity without going sour quickly. A common default for tropical snakes.
safeAspen shavingsThe classic for colubrids. Excellent for burrowing; replace any patch that gets wet.
safeTopsoil and coco fibre mixBioactive-ready and holds a burrow.
safePaper towel or newspaperQuarantine, feeding response problems, and post-surgery.
safeWith a caveat
Aspen in a high-humidity setupIt moulds. Aspen suits dry-side species; wet species need mulch or soil.
with a caveatNever
Pine and cedarAromatic phenols.
neverSand for species that are not desert animalsAbrasive and dries the skin, causing shed problems.
neverStuck shed and retained eyecaps are usually a humidity failure during the blue phase, not a substrate failure afterwards.
Compare with other animals
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