brachypelma vagans growth

What is the growth rate of the b vagans.

I have never raised one from a sling but I hear they are the fastest growing brachypelma along with albopilosum. If this is the case expect it to grow about an inch in 4months... My gfs was about half an inch when we got it 4 or so months ago and is now about 1 3/4 in..

Moderate growth rate. You have a good deal of control over that depending on temps and amount and frequency of feedings. Keep it 68 and feed it a couple times a month and it'll be slow. Keep it 80 and feed it a couple times a week, and it'll dwarf ones kept cool and fed sparingly.

There are few absolutes with tarantulas.

Mine got from ~0.3" to ~5" in a year.
As poec54 said, keep warm and feed more.

I got mine at 1/3" in April. For the first 6 months it grew amazingly slow...fairly long time between molts, little growth with each, and an inconsistent appetite. After 7+ months is had reached about an inch...finally. From that point on its been positively voracious, eating everything offered, only pausing a short time before molting, which it began doing on a 30-40 day schedule. In the last 3+ months its molted 3 times and has grown to 2.25"...and is just entering pre-molt yet again.

I've kept it warm (approx. 80) and offer food every 2-5 days...it did not matter until the t reached that magic 1" mark.

I find that that 1-1.5" mark is a common size amongst t's to go on a major growth spurt.