Substrate is simply the bedding in your blood python's cage. In addition to absorbing any waste your snake passes, substrate may also serve as a hide, and can aid in maintaining humidity within the enclosure. While one's choice of substrate is largely a matter of personal preference, there are a few key points to keep in mind when selecting a substrate for your blood or STP.

What Kind of Substrate Do I Need?

Choice of substrate is usually pretty straightforward. First of all, determine whether you prefer a sheet type substrate like newspaper, or a particle substrate such as cypress mulch. Particle substrates allow for spot cleaning, where the soiled areas are removed and replaced with fresh bedding, and complete bedding changes are performed only as necessary. Sheet substrates must be completely changed when soiled. Both types of substrate can double as hides: blood pythons can burrow into a particle substrate, or sit between layers of a sheet substrate to feel secure. Additionally, sheet and particle substrates can be misted to help raise cage humidity, although some types hold up to moisture better than others.
      Ultimately, your substrate of choice will probably hinge on aesthetics, ease of management, and cost. Some keepers can't stand the appearance of newsprint in their cages, while others appreciate its low cost and widespread availability. You may be the kind of keeper that doesn't mind paying a little extra for double-milled cypress mulch due to the more natural appearance it creates in your enclosures. If you maintain a large collection, you may prefer a particle substrate that allows for simple spot cleaning; on the other hand, your collection may be so big that free newspaper from friends & recycling bins may be your most cost-effective method. These are all points to keep in mind when making your substrate selections.

Sheet Substrates: Types & Considerations
While this is not an all-inclusive list, here are some commonly-used sheet substrates. Click on each photo for pros, cons and comments on each substrate:

Particle Substrates: Types & Considerations
Again, not an inclusive list, but a good selection of particle substrates (some common, others not so much). Pros, cons and comments in photo captions.

Substrates to Avoid
      Just as there are many substrates that work well for blood & short-tailed pythons, there are also a few that we feel should be avoided. Some are toxic, some are irritants, and others simply aren't effective substrate solutions.

Cedar Shavings - The oils in cedar are toxic to snakes. This substrate should be avoided completely.
Pine Shavings - Pine is extremely dusty, and its oils can be very irritating to a snake's resipiratory tract.
Orchid Bark or Reptile Bark - These chunks of fir tree bark are not as asborbent as substrates made up of smaller particles.
They also present a hazard if swallowed during feeding.
Astroturf, "Reptile Carpet" - Not as absorbent as other choices; may be difficult to effectively clean/disinfect.
Sand - Heavy, dusty, may accumulate between scales and cause irritation. Repeated ingestion may cause impaction.

Fortunately the list of safe, frequqently-used subtrates is much longer than those that should be avoided. With a little planning and common sense, it is easy to select a substrate that works well for your blood python and your caging solution, as well as your budget and preferred level of maintenance.

Additional Considerations
     There are almost as many different types of effective substrates as there are caging solutions. You may need to experiment with a couple of different types to find the one that works best for your setup. It's pretty hard to go wrong with paper substrate, like newspaper or kraft paper, and we've used this extensively throughout our snake keeping experience. For discussion on different substrates, you can also visit our caging subforum, part of the husbandry forum on our message boards. Threads specifically pertaining to substrate will be tagged with that heading.

Now that you have a good idea of the pros and cons of various substrate, let's address an extremely important aspect of creating the right environment: proper heating, and temperature control.