1.Every few months try a shot of Geritol or 1 tbsp. (15 mL) of castor oil, followed by watering.
2. Or dissolve 1 tbls. (15 mL) gelatin in 1 cup (250 mL) of hot water. Slowly add 3 cups cold water. Water plants with this during the growing season.
3. Another lift to plants will come from that stale club soda sitting around in the fridge! Warm it to room temperature before use.
from: Better House and Planet by Marjorie Harris