Start fertilizing the year after planting.
There are several different types of hydrangeas—bigleaf, panicle, smooth, oakleaf, mountain. All these types should be fertilized at least once a season in late winter or early spring, certainly by the time new growth begins to show around the base of the plant.
Miracle-Gro Performance Organics Blooms Nutrition
This is an all-purpose blossom booster that's suitable for use on a wide variety of perennial and annual blooming plants, including hydrangeas.
It's best to start adding coffee grounds to the soil months before the blooming season begins, ideally in the late fall. You can repeat the process with your typical fertilizing schedule. With a little caffeine and a lot of patience, your hydrangeas should reward your efforts come spring with the boldest blue globes.
By altering the soil pH with vinegar, you can actually turn your pink-flowering hydrangeas blue! For this trick, simply dilute your vinegar in water before pouring it around the base of your hydrangeas, and within just a few weeks you could have fresh and bountiful blue blooms.
Though hydrangeas prefer protection from hot direct sun, too much shade can prevent them from forming flower buds. Ideal light conditions for hydrangeas are several hours of direct morning sun with afternoon shade, or dappled shade that allows plenty of bright indirect light.
There are plenty of reasons why your hydrangeas may not be blooming as much as they once did. Conditions like extreme heat, drought, or excessive sun exposure can all impact how many flowers your shrubs produce. Pruning is also an important consideration.
Also, when you do water, after a week or 10 days, water with a water soluble fertilizer such as Miracle Grow, Rapid Grow or Peters 20-20-20. Apply this water soluble fertilizer every second or third watering and see if the plant doesn't do better.
Water at a rate of 1 inch per week throughout the growing season. Deeply water 3 times a week to encourage root growth. Bigleaf and smooth hydrangeas require more water, but all varieties benefit from consistent moisture.
This common household item is surprisingly effective at helping perk up plants and brighten blooms. For hydrangeas specifically, adding baking soda helps the plant retain more moisture in the roots. When this happens, the result is bigger blooms with more vibrant colors that last longer than they would otherwise.
Most hydrangeas prefer partial sun with full sun in the morning, followed by some afternoon shade. This is especially true for the Bigleaf hydrangea (H. macrophylla). Some varieties are more tolerant of full sun. Most hydrangeas will thrive in fertile, well-draining soils that receive plenty of moisture.
If you don't prune hydrangeas then they can eventually resemble a tangled mass of woody stems, and the flowers will become smaller and less showy.
Let these plants grow a season or two before doing any serious "hard" pruning. Once the shrub is established and has a couple of growing seasons under its belt, prune these hydrangeas in the spring down to the ground, or not at all if you want a larger shrub. Flower buds will grow on this season's growth or new wood.
Bigleaf Hydrangeas: Bigleaf Hydrangeas are the most popular type of Hydrangeas. They begin blooming in late May or June in warmer climates and later in the summer in cooler climates. Some Mopleaf varieties are remontant, meaning that they bloom twice in a season.
Most common hydrangeas prefer a partial sun location - ideally receiving sun in the morning hours and shade in the afternoon. The reblooming Endless Summer® Hydrangea series prefers part shade.
You can use vinegar to lower the pH of your soil, but be aware that in order to achieve blue blooms, you will need both an acidic environment and aluminum ions. The acidic environment will also need to be a sustained over a period of time, which could be hard if rainwater is washing the vinegar away.
First, add a 1/4 cup of sugar to the room temperature water in the vase. The sugar helps feed the stems and increases the life of the cut flowers.
Adjust the Soil pH
Organic acidifiers include sulfur and sulfate. There are also easy-to-use soil additives made specifically for hydrangeas. Bailey's Color Me Blue (soil sulfur) or Bailey's Color Me Pink(garden lime) change the pH of the soil so you can enjoy the hydrangea bloom color you want.
Pickle juice is mostly composed of vinegar, which can help to lower the pH of the soil and make it more acidic, which can be great for plants like Hydrangea, Gardenia, Camellia, Azalea, Begonia, Impatiens, Rhododendron, Blueberry, Potentilla, Heather, Vinca, Clematis, Fuchsia, and Astilbe.
Espoma Organic Traditions 6 lb. Garden Sulfur Soil Acidifier is an all-natural mineral that can be used to lower the pH of your soil. It can also provide plants with sulfur, a nutrient that promotes growth and dark greening. It will turn hydrangeas from pink to blue.