In Brief: Can Ashwagandha Make you Taller?
No scientific studies are found proving the claim that ashwagandha can increase the height of the individual. There is limited evidence that ashwagandha increases GABA in the brain. The increase in GABA may increase growth hormone, which in turn can increase height. Therefore, studies are required in the future to determine if ashwagandha ingestion increases size.
Ashwagandha is a herb that has many flavonoids and active ingredients that help in supporting human health.
Poor diet and lifestyle factors affect the height of the individuals. The studies determining whether ashwagandha increases the size of an individual is yet to be found.
Few studies have suggested that ashwagandha may increase a neurotransmitter, GABA, in the brain.
In a study, the authors cited the growth-promoting effect of ashwagandha in 60 healthy children. The treatment resulted in a slight increase in hemoglobin, packed cell volume, mean corpuscular volume, serum iron, body weight, and handgrip.
Another mice study also showed that chronic ashwagandha treatment increased GABA levels significantly.
Studies have suggested that an increase in GABA may cause an increase in the human growth hormone, which in turn plays a role in increasing the height of the individual.
The oral administration of 5g GABA caused a significant elevation of plasma growth hormone levels.
Another study also suggested that oral administration of the GABA stimulates both immunoreactive as well as immunofunctional growth hormone.
The increase in growth hormone was both at rest and following exercise.
Also, studies have shown that height has a positive correlation with total body mineral density in adolescent girls and boys.
Some studies have shown that withaferin isolated from the ashwagandha may play a role in the stimulation of new bone formation. It may prevent bone loss due to calcium deficiency. 
However, it is not clear if ashwagandha can increase height by stimulating new bone formation.
The scientific studies showing the direct association between ashwagandha on increasing the height is not found.
Therefore, well-designed trials in the future will determine if ashwagandha increases height.