Growin is a module that calculates the flux-tube-integrated linear Rayleigh-Taylor instability (grow)th rate of (i)o(n)ospheric irregularities is often used in the study of equatorial spread F(ESF). The Rayleigh-Taylor instability is often the prevailing explanation for the growth of plasma irregularities in the bottomside into plumes of depleted plasma, therefore a computation of its growth rate is valuable. This package includes many common approximations used in the computation of the Rayleigh-Taylor growth rate. Although not the focus of this discussion, Kelvin-Helmholtz instabilitiesfrom neutral wind shear below the bottomside F region are another source of plasma instability in the bottomside F region intended to be included in this package eventually.