The invention provides methods for improving germination of manufactured seeds. The manufactured seed of the invention comprises a seed coat, nutritive media comprising an adsorbent material in a concentration from about 30 g/L to about 100 g/L, and a shoot restraint comprising a cavity. The manufactured seed further comprises a plant embryo. The adsorbent material may be nutrient-treated or non-nutrient-treated charcoal. The manufactured seed may optionally contain an adsorbent material in the cavity of the shoot restraint.