Plant Ultra Overview A growth enhancer for all your plants Plant ULTRA is formulated for the use with all plants grown in pots and containers. It will enhance the performance of the plant and improve the long-term fertility of the soil. Regular use will encourage and support growth, brighter flowers and long-term performance. Plant ULTRA is a highly concentrated blend of pure plant acids and extracts. This nutrient should be diluted and supplied to roots for long-term fertility in the growing medium.