Enclosure:
They Need A Large, Secure Enclosure:

A young boa can start out in a 20-gallon tank, but the snake will quickly outgrow these quarters and require a more spacious enclosure that in most cases will be custom built. For the health and well-being of an adult boa, its enclosure should be at least 75-85% of the snake's overall body length. So a 12' long boa should have an enclosure that covers a minimum of 9 square feet. Typically, this would be an enclosure that measures 6-7' long by 2-3' wide. A boa's enclosure should also be high enough (about 3') to allow a shelf to be installed. Porous material such as unfinished wood should be avoided when building a snake enclosure, since it is difficult to clean and can harbor bacteria.

Putting Shelves In Their Enclosure Is A Good Idea:

Shelving will give the boa a chance to climb. A sturdy shelf also makes it easier to provide the boa with a thermal gradient by having a heat lamp directed at an area of the top shelf, while the lower area of the enclosure provides a cooler spot. If you use climbing branches instead of shelving, make sure they are strong enough to support the weight of an adult boa.

They Need A Place Where They Can Hide:

Their size and strength notwithstanding, Boas will feel vulnerable in an enclosure that does not provide them with secure hiding areas. A boa's enclosure should have a minimum of two hiding areas, one in the warming area and one in the cooling area.

Temperature:
A Thermal Gradient Must Be Maintained For Them:

The ambient temperature in a boa's enclosure must be kept around 85 F. A boa must be provided with a basking area in
the 90 F range. At night, the ambient temperature can drift down to the upper 70s or low 80s. If the temperature is kept too low, a boa is liable to refuse or regurgitate food, and
develop digestive and respiratory problems. A boa's enclosure can be heated by placing heat pads under a section of its base, by using a large rigid pig blanket, infrared bulbs or
ceramic heat emitters. Hot rocks should never be used, since they can burn a snake's skin. The temperature in a boa's enclosure should be measured by two thermometers (one in
the basking area, the other in the cooling area) positioned one inch over the substrate. A rheostat or thermostat should be used to regulate heat. Important - see the Note About Day/Night Light Cycles and Heating below.

Their Enclosures Should Be More Humid During The Shed Cycle:

The humidity level in a boa's enclosure should be about 60% during normal times and 70-75% when the animal is
shedding. A boa's enclosure should be humid but not wet. This can be accomplished by having a large water bowl in the enclosure, misting a cypress mulch substrate, misting the
snake itself or adding a humidity box. Always use water that is free of chlorine and other heavy metals for bowls, misting and humidity boxes. Many boas will shed once a month, if they are well fed. Others shed every two or three months. Boas go through a 4-day pre-shed period when their eyes become cloudy. It's a good idea to mist a boa daily during the pre-shed period and increase this to 2-3 times a day after the eyes clear. Maintaining adequate humidity levels is essential to successful shedding. Boas will also like to soak themselves in water.

Note About Day/Night Light Cycles and Heating:

All reptiles, including this pet, must have distinct day and night periods in their enclosure to maintain their biological rhythms. (See the lighting entry above for the specific length of this animal’s day/night cycle.) The day period must be light; and night must be dark. A timer should be used to set day/night periods. If a heat source is required to maintain correct nighttime temperatures, use heat mats or strips mounted below or on the side of the tank, infrared heat lamps, ceramic heat emitters, or a combination of these products. This will allow the enclosure to be heated while remaining dark. Follow directions carefully with all products. If ceramic heat emitters are used always choose fixtures with porcelain or ceramic sockets and to protect against fires do not place them by dry wood or flammable fabrics. Ceramic heat emitters must be kept out of the reach of children and all pets, including dogs and cats.

Diet:
They Are Big Eaters:

Boas are large snakes with large appetites. Very young boas
should be given a pre-killed pinkie feeder every five days. (Boas should not be fed more often to "help" them grow faster, since this will only cause medical problems later in life.) As the snake grows it can be given an adult mouse or pre-killed fuzzy rat (under 10 days old). Later as an adult, the snake can be fed larger rats, feeder chickens and frozen and thawed rabbits. It is better for a boa's health to be fed a smaller meal every week than to gorge on a large feast every 2-3 weeks. However, some adult boas won’t accept food every week, but all boas need to be fed ever 2-3 weeks. The individual snake's owner will have to use common sense and experience to determine the diet and feeding schedule that works best for the boa as an adult.