Kale cultivation in Indonesia is still done conventionally or grown in the ground using chemical fertilizers and pesticides. Cultivating kale on the ground requires a large area of land and extra labor. An alternative is hydroponic kale cultivation using nutrients from liquid organic fertilizer. One of the ingredients added in LOF is leguminous plants. The addition of leguminous plants can affect the amount of nutrients contained in the LOF. This study aims to identify the effect of POC and seedling age on the vegetative growth of kale (Brassica oleraceae v. Red russian) grown hydroponically in lowland areas. The research was conducted using a Factorial Split Plot Design with two factors and four replications. The main plot was fertilizer treatment with 3 levels, namely: AB Mix (P1), combination of liquid organic fertilizer and AB mix (P2), liquid organic fertilizer (P3). Subsidiary plots are seedling age with 3 levels, namely; seedling age 7 days after seedling (DAS) (B1), seedling age 14 DAS (B2), seedling age 21 DAS (B3). The observations made were plant height and number of leaves at the age of 1, 2, 3, 4, 5, 6, and 7 weeks after planting (WAP). Observation data were analyzed using ANOVA (Analysis of variance). Treatments that had a significant effect were continued with the 5% BNT further test. The results showed that the combination of fertilizer treatment and seedling age had no significant effect on plant height and number of leaves in all observation periods. AB mix + LOF nutrition affects the vegetative growth of kale plants hydroponically and is not significantly different from AB mix nutrition. Seedling age did not affect plant height and number of kale leaves, but seedling age 7 DAS tended to have the highest yield in plant height and number of kale leaves.