Size and growth
Adult Grammostola pulchra reach roughly 15–18 cm (6–7 in) and are slow growers. Adult Grammostola rosea reach about 12–15 cm and are very slow growers. That affects how quickly Brazilian Blacks and Chilean Rose Tarantulas move through sling and juvenile enclosure sizes.
Do not use size alone to estimate age in either Grammostola pulchra or Grammostola rosea. Sex, feeding and individual variation can change the pace of growth even when two spiders began at a similar size.
Enclosure and lifestyle
Brazilian Blacks are terrestrial, while Chilean Rose Tarantulas are terrestrial. Build the Grammostola pulchra enclosure for a terrestrial spider and the Grammostola rosea enclosure for a terrestrial spider instead of assuming two tarantulas need the same shape of setup.
For Grammostola pulchra, substrate depth, retreat position and usable space should match its terrestrial lifestyle. Apply the same rule separately to Grammostola rosea; the enclosure should make normal behaviour easy rather than forcing either species into a generic layout.
Temperature, water and moisture
A practical temperature range for Grammostola pulchra is 20–24°C; for Grammostola rosea, it is 18–26°C. Stable room conditions are more useful for both species than chasing small fluctuations within those ranges.
For Grammostola pulchra, keep a mostly dry setup with surface, water dish, and a modest moisture gradient rather than constantly wet substrate. For Grammostola rosea, use generally dry to lightly moist with a water dish; avoid persistently wet substrate. In both enclosures, keep fresh water available and adjust substrate moisture to how quickly the setup actually dries.
Temperament and maintenance
Grammostola pulchra is a New World species, while Grammostola rosea is a New World species. That background is useful when planning maintenance, but individual Brazilian Blacks and Chilean Rose Tarantulas can still differ noticeably in speed and defensiveness.
With both Grammostola pulchra and Grammostola rosea, locate the spider before opening the enclosure, use long tools when they make the job safer and keep a catch cup ready for rehousing. Handling is not required for routine care.
Male and female lifespan
Male Grammostola pulchra generally live around 5–8 years, while females can live 20–30 years. Male Grammostola rosea generally live roughly 4–8 years, while females can live 15–25+ years.
Those lifespan ranges make sex particularly relevant when comparing Grammostola pulchra with Grammostola rosea. A confirmed female of either species is normally a much longer commitment than a mature male, and the exact age of an older juvenile may be impossible to know.
UK availability and trade notes
In the UK hobby, Grammostola pulchra is currently classed as common, while Grammostola rosea is classed as common. Stock changes between specialist sellers, captive-produced batches and show weekends, so availability should be checked at the time of purchase.
For records and purchases, use the scientific names Grammostola pulchra and Grammostola rosea as the main identifiers. Current trade notes list Grammostola pulchra as 'Not CITES-listed' and Grammostola rosea as 'Not listed', so check current requirements before any international movement where controls may apply.
Practical difference in day-to-day care
The practical difference between Grammostola pulchra and Grammostola rosea comes from the combination of lifestyle, adult size, growth and moisture needs. Those factors change how much substrate, vertical space and maintenance access each enclosure needs.
Whichever species you keep, let the individual spider settle into an enclosure designed for its own biology. That applies equally to Grammostola pulchra and Grammostola rosea: fresh water, secure housing and patient observation matter more than trying to make the two species behave the same way.