Since fungal mycelial mats in potato dextrose broth are not suspended, growth is usually monitored indirectly. One common method is to periodically harvest the mycelium, blot to remove excess liquid, and determine biomass by fresh weight or, more accurately, by drying to constant weight for dry biomass measurement. Alternatively, optical density is unsuitable due to clumping, but glucose depletion or total soluble solids in the medium can serve as indirect growth indicators. Imaging the mats and measuring surface area expansion is also useful. Combining dry weight determination with substrate utilisation provides a reliable measure of growth over time.

It is possible, An accurate way to determine fungal growth over time in a liquid medium is through a spectrophotometer. This method measures the turbidity or cloudiness of the medium, which is directly proportional to the number of fungal cells present. As the fungi grow and multiply, the medium becomes more opaque, and the spectrophotometer detects this increase in turbidity.