Hydrangea is a shrubby perennial with pompom-form flowers that can be pink, white, purple, red, and even blue--depending on the variety and the pH level of the soil. These flowers can be grown as indoor potted plants or outdoors in the garden. Whether inside our out, hydrangeas benefit from a good fertilizer. Scotts Miracle-Gro, a water-soluble, all-purpose plant food, is appropriate for fertilizing hydrangeas indoors or out.
Place 1tbsp. of Miracle-Gro into a gallon-sized watering can.
Add one gallon of water, and mix the two ingredients together.
Pour the fertilizer over your hydrangeas at a rate of one gallon per every ten sq. ft.
Repeat once per week during the growing season to keep your hydrangeas fed and healthy, according to Texas A&M University Extension.