Basic Care: Green Iguana


Iguanas are very popular petsGreen iguanas are very popular pets. They are perhaps one of the most misunderstood and poorly kept of all reptile pets. They can reach considerable size. Recorded weights and lengths of adult male iguanas have been as much as 20 pounds and 7 feet respectively. Certainly not every iguana will become such a giant. But when considering an iguana’s environmental needs, such size factors should be taken into account. They also have specific temperature, humidity, lighting, and dietary needs.


Keep in mind your cute little hatchling iguana will someday be much bigger. You may start with a small 20-gallon aquarium now, but one day you will need a custom cage or room dedicated to his reptilian needs. Surfaces of your chosen enclosure should be smooth. Iguanas will rub their scales off their noses and hurt their feet if their enclosure is made of wire. Wood may be used so long as it has been sealed with exterior polyurethane varnish (such as marine varnish or similar). Allow the coating to cure for several days and air it out well before inhabiting it. Molded plastic and acrylic cages work well until the iguana out grows them. Iguanas should never be kept loose in the house. There are to many dangers this way, such as animal attacks, accidental injuries, and chilling.

Your iguana will need branches to climb on. Chose branches of appropriate diameter and strength to support his weight. Branches from outside can bring in pests. I suggest either baking at 320 for 20 minutes or drying out over the outdoor gas grill for 30 minutes. Keep branch away from flames (for the obvious reasons). Choose hard wood always. Pine and cedar will smoke heavily when baked! I usually use maple or oak.

Security is especially important for small iguanas. For these little guys I suggest covering half the exterior of the cage with paper or towels to provide a safe refuge from perceived predators (i.e. you, the dog, the cat, etc). Eventually you can remove this covering, once the little guy has acclimated to his new surroundings (6 months or so). Silk plants may look nice in the cage, but most iguanas will eventually try to eat them. They can be placed outside the cage instead.


I recommend newspaper or outdoor carpet. Newspaper should be changed often. If you choose outdoor carpeting, have several pieces. This way you can be sanitizing one and still have another to place in the cage. I do not recommend any particulate bedding, (corncob, wood chips, wood shavings, etc.). It is swallowed easily by iguanas. Intestinal blockage will lead to death if not addressed quickly. Particle bedding also hides a mess well. The moisture from spilled water, feces and urine build up in particulate bedding and will promote bacterial infections in your iguana.


An iguana can not digest properly or have a competent immune system with out the ideal heat. He is an ectotherm, which means he is the same temperature as his surroundings. The preferred optimum temperature zone (POTZ) temperature for green iguanas is 85 to 95. The ideal nighttime temperature is 80-85. A gradient within the enclosure is ideal. This way the iguana can heat up and cool down as his body requires. Maintaining temperature is difficult. Most enclosures require a heating mat applied outside the cage with a thermostat to maintain nighttime temperatures. For basking, a reflector with appropriate wattage bulb will do. A branch should be provided under the bulb. For iguana rooms, a space heater can be used. Build a protective barrier around it so the iguana can’t get burned. Protect your iguana from burns by using a thermometer to figure out the high and low temperature areas of your cage before you place him in it. Never allow the iguana to touch the heat mat or bulb directly. Severe burns will occur. Hot rocks are not appropriate. Your iguana is a basker, meaning he gets his heat form basking in the sun. The hot rock will not heat the enclosure and will promote burns and dehydration for your iguana. Do not place a glass enclosure in direct sunlight. It will overheat and cook your lizard. Lights should go off at night. I use timers on my lights.

Humidity and water

Iguanas should be provided with a large water bowl. I recommend a large lasagna pan or cat litter box. It must be cleaned daily. Iguanas generally use their water bowl as a toilet, thus requiring frequent changes. Humidity is difficult to maintain in most iguana enclosures. Daily misting will help. Soaking in the bathtub weekly is also a good idea. The tub should have warm water to iguana shoulder level. Allow him to soak for about 20 minutes. Never soak a weak or debilitated iguana without complete supervision. The enclosure should never have condensation on the walls. This means you need more ventilation or your cage is too wet. Skin infections often occur when the enclosure is excessively moist. A hygrometer will read the ambient humidity. Ideally, iguanas need 65-75%.

Ultraviolet-B Radiation (Also known as UVB)

This is a one of the key elements in keeping a healthy iguana.  Reptiles produce vitamin D in their skin through exposure to UVB radiation.  Vitamin D is important in calcium metabolism.  UVB wavelength measures 290-320 nm.  When purchasing a UVB source, check to make sure it provides this wavelength.  There are several fluorescent bulbs to choose from.  Repti-sun fluorescent bulbs or mercury vapor bulbs produce adequate UVB.  The mercury vapor bulbs produce heat as well as UVB.  They are very intense and penetrate 2 to 3 feet into an enclosure and up to 12 feet with increased wattage. The amount of UVB will be diminished if it paces through glass or plastic.  I recommend placing it on screen material.  The iguana should be no more than 12 to 24 inches from the fluorescent bulb.  Exposure time should be 8 to 10 hours daily.  Fluorescent bulbs need to be replaced every 6 to 9 months because the UVB production stops about then.  I date my bulbs with a permanent marker to keep track of replacement times.


This is another key to keeping healthy iguanas.  What you feed your iguana will determine its lifespan.  Proper nutrition from the start will ensure healthy bones and kidneys.  All food materials should be adequately washed, chopped and mixed.  Young iguanas need their food finely chopped.  They may be fed twice daily.  As they age, feeding frequency decreases to once a day, then every other day for adults (3 feet and longer).  Ingredients for sub-adult meals should include items from these categories:

  1. Calcium rich vegetables: 60% of diet, 2 or more items per feeding-turnip greens, mustard greens, beet greens, kale, collards, bok choy, Swiss chard, dandelions, parsley, romaine, escarole, and spinach.  Spinach must not be over used as it binds iodine and calcium.
  2. Other vegetables: 30% of diet, a variety weekly.  Frozen mixed vegetables, squash, zucchini, sweet potato, bell pepper, broccoli, peas, beans, okra, carrot, and pumpkin.
  3. Fruit: 10% contain mostly fructose and fiber.  Dilutes more valuable nutrients in other food items, so minimize its use.  Figs, papaya, melon, apple, peaches, plums, strawberries, tomatoes, banana (with skin), grapes, kiwi

Adult Iguanas are primarily fed the calcium rich veggies with small amounts from the rest of the list periodically.  Senior Iguanas are primarily calcium rich greens.

Vitamin supplementation is most important in to growing iguana.  A multivitamin supplement should be used twice weekly.   Examples include Reptivite (Zoo-Med), Reptical (Tetra), Nekton, and human Centrum.  A straight calcium supplement should be used 4 to 5 times weekly.  This supplement should contain no phosphorus and does not need vitamin D.  Iguanas seem to be unable to absorb vitamin D well from their diets.

*Older iguanas (adults) require a multivitamin once to twice monthly.  Calcium may be given once weekly.


Cage cleaning should include thorough scrubbing and disinfecting. For washing, use non-toxic soaps such as dish soap. Rinse well. For disinfection, dilute bleach (1:10), chlorhexadine, or Roccal (Upjohn, Kalamazoo). These must be rinsed very well. Allow cage to air out well before iguana is returned. Daily removal of food is important.


Here is a list of great references for green iguana keeping:

De Vosjoli, P: The Green Iguana Manual. Lakeside, Ca, Advanced Vivarium Systems, 1992.

M. Kaplan, Iguanas for Dummies. IDG Books