In order to investigate the interactive influence of humic acid foliar spray on physiological growth indices in Redgram (Cajanus cajan ). The study was conducted during Kharif 2018-2019 at Main Agricultural Research Station, UAS, Raichur by using a randomized block design. The effectiveness of humic acid was studied with different levels as T1 – Humic acid liquid 15% @ 1.0 ml/l of water, T2 – Humic acid liquid 15% @ 1.5 ml/l of water, T3 – Humic acid liquid 15% @ 2.5 ml/l of water, T4 – Humic acid liquid 15% @ 4.0 ml/l of water, T5 – Planofix 4.5 % @ 20ppm and T6 – as a control. After the collection of data from redgram at different growth stages i.e. 30, 60, 90 DAS, and at harvest all the physiological growth indices including total leaf area, Leaf area index (LAI), total dry weight (TDW), , relative crop growth rate, crop growth rate (CGR), net assimilation rate (NAR), leaf area duration were measured. Significant differences (p<0.5) were observed for all the above-mentioned growth parameters across the humic acid concentration levels. Changes trend of total leaf area, Leaf area duration, leaf area index, and total dry matter significantly increased while the increased in the concentration of humic acid foliar spray. LAI, LAD, and NAR, like other growth indices, responded to the foliar sprays of humic acid and contributed the positive responses for an increase in the yield of redgram crops.