Quick answer: The best substrate for most tarantulas is a soft, peat- or coco-based soil that holds a burrow, retains some moisture and does not go mouldy easily. A purpose-made blend such as Jurassic ABG Tarantula Mix, plain coco fibre, or an organic topsoil and coco mix all work well. What matters more than the brand is matching depth and moisture to your species: deep and diggable for burrowers, moderate for terrestrials, and a shallower layer with plenty of height for arboreals.
What a tarantula substrate needs to do
- Hold a burrow. Many species dig or rework their substrate. It should keep its shape when packed lightly and not collapse when dry.
- Manage moisture. It should hold humidity in the lower layers without becoming waterlogged on top. Soggy, stagnant substrate is a common cause of problems.
- Cushion falls. Heavy-bodied terrestrials can rupture their abdomen in a fall. A soft substrate and limited climbing height reduce that risk.
- Be safe. No fertilisers, pesticides, aromatic woods or sharp grit.
Substrate options compared
| Substrate | Burrow holding | Moisture | Best for | Notes |
|---|---|---|---|---|
| Jurassic ABG Tarantula Mix | Good | Holds moisture, stays airy | Most terrestrials, burrowers, bioactive tarantula builds | Canadian-made, ready to use. Check the listing for ingredients. |
| Coco fibre | Good when damp, loose when dry | Holds moisture well | All-round use, slings, tropical species | Cheap and easy. Dries dusty on top. Also sold as compressed bricks. |
| Organic topsoil (no additives) | Very good | Moderate | Burrowers, dry-loving terrestrials | Must be free of fertiliser and perlite. Often mixed with coco. |
| Peat moss | Good | Holds a lot of moisture | Tropical burrowers | Usually mixed with other components rather than used alone. |
| ABG-style terrarium mix | Moderate (chunky) | High | Arboreal setups with live plants | Great for planted vivariums. Less ideal for pure burrowers. |
| Vermiculite | Fair | High | Mixed in small amounts | Some keepers mix it in for moisture. Rarely used alone. |
Jurassic ABG Tarantula Mix
Jurassic Reptile Products makes its Tarantula Mix in Canada as part of the same range as its ABG Terrarium Mix and Semi-Arid Blend. It is designed as a ready-to-use substrate for tarantulas and other invertebrates, so you do not need to blend topsoil, coco and other components yourself. We do not publish a recipe or performance figures beyond what the maker states: check the product page for the current ingredient list.
Where a dedicated mix helps most is in burrowing setups and bioactive tarantula enclosures, where you want something that holds tunnels, supports springtails and isopods, and does not compact into a hard block over time. If you keep one or two easy terrestrials and are happy mixing your own, coco fibre with some topsoil does the job for less money. That is an honest trade-off, and both approaches keep tarantulas healthy.
Depth by tarantula type
Terrestrial species
Species such as the curly hair, Chilean rose, Brazilian black and Mexican red-knee like enough substrate to dig a scrape or partial burrow. A useful rule is a substrate depth of at least the spider's leg span, and enough that the gap from substrate to lid is no more than about one and a half times the leg span. That limits fall height. Provide a hide such as a half cork round pressed into the substrate as a starter burrow.
Obligate and opportunistic burrowers
Many Old World species, such as the orange baboon tarantula, and a number of New World species dig deep burrows if given the chance. Offer 15 cm or more of firm, slightly damp substrate. These species are fast and defensive, so they are not beginner animals.
Arboreal species
Arboreals such as the pinktoe, Antilles pinktoe and Indian ornamental need height, a vertical cork tube to web in, and good cross-ventilation. A substrate depth of about 5–8 cm is plenty. Avicularia and Caribena species in particular do poorly in stagnant, wet enclosures, so keep the substrate only lightly damp and prioritise airflow. See top 10 arboreal spiders for species notes.
Moisture: getting it right
Most popular beginner species, including Brachypelma, Grammostola and Tliltocatl, do well on mostly dry substrate with a water dish and one damp corner, which you overflow occasionally. Tropical species such as the goliath birdeater need substrate kept consistently damp, but never soggy, with good ventilation. Slings of nearly all species dry out faster than adults, so keep a little moisture in their substrate. In Canadian winters, forced-air heating dries enclosures quickly, so check more often from November to March.
Substrates to avoid
- Cedar or pine shavings: aromatic oils can harm invertebrates.
- Gravel or decorative stones as the main layer: hard, no burrowing, and dangerous in a fall.
- Calcium sand or pure play sand: burrows collapse and the surface is abrasive.
- Garden-centre potting soil with fertiliser, perlite or wetting agents: chemical additives and sharp perlite are not worth the risk.
- Soil collected outdoors: can bring in pesticides, mites and parasites.
Can you keep a tarantula bioactive?
Yes, and many keepers do. A planted enclosure with a soil-based substrate, leaf litter and springtails stays cleaner because uneaten food and boluses are broken down. Use small, gentle clean-up crew species such as springtails and dwarf white isopods. Large, active isopods may disturb a moulting spider. Remove uneaten crickets within a day for the same reason. Our page on creating a bioactive haven for tarantulas walks through a full build, and the clean-up crew guide covers species choice.
How much substrate to buy
Multiply the enclosure's floor length by width by your chosen depth for the volume, then add about 10 percent for settling. Our substrate calculator does the maths for you. For a typical 30 x 30 cm terrestrial enclosure at 10 cm deep, that is about 9–10 litres. If you are still choosing a species, start with top 10 tarantulas for hobbyists.
FAQ
What is the best substrate for a beginner tarantula?
Coco fibre, a coco and organic topsoil mix, or a ready-made tarantula mix such as Jurassic ABG Tarantula Mix all work well for beginner species like the curly hair or Chilean rose.
How deep should tarantula substrate be?
For terrestrials, at least the spider's leg span, with the lid no more than about one and a half leg spans above the surface. Burrowers need 15 cm or more, and arboreals about 5–8 cm.
Should tarantula substrate be wet or dry?
It depends on the species. Most beginner species like mostly dry substrate with a damp corner and a water dish, while tropical species need consistently damp but not soggy substrate.
Can I use sand for a tarantula?
Not on its own. Sand does not hold burrows and can be abrasive. A little sand mixed into topsoil is fine for some desert species.
Is ABG mix good for tarantulas?
ABG-style terrarium mix suits planted arboreal setups. For burrowing and terrestrial species, a finer tarantula-specific mix or a coco and topsoil blend holds tunnels better.
How often should I change tarantula substrate?
In a bioactive setup, rarely. In a simple setup, spot-clean waste and old food, and replace the substrate if it smells sour, grows persistent mould or hosts a pest outbreak.