Many customers ask why their hydrangeas aren't blooming. The primary reasons hydrangeas don't bloom are incorrect pruning, bud damage due to winter and/or early spring weather, location and too much fertilizer.
Best Fertilizer For Hydrangeas
Organic, slow-release fertilizers for roses (such as a 15-10-10, or 10-5-5 formula) work well on hydrangeas, giving the plants the nutrients they need to increase the size and quantity of their blooms.
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.
Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil. The coffee grounds make the soil more acidic, allowing the hydrangea to more easily absorb aluminum. In addition, fruit peels, lawn clippings, peat moss and pine needles, are thought to have a similar effect.
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.
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.
Select the best fertilizer for hydrangeas.
Balanced granular fertilizers such as Espoma Rose Tone and Holly Tone are good choices.
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.
The easiest thing to do is to pick up a jar of alum at the grocery store (in the spice aisle) and keep it on hand for your cut hydrangeas. As you cut the stems, dip them quickly into the alum jar and then plunge them into a vase or pitcher filled with water.
In addition to bolstering future blooms and strengthening stems, deadheading your hydrangeas has aesthetic benefits, too. "Removing faded flowers creates a neat and tidy appearance, which many gardeners prefer over the look of leaving dried flowers on the plant," says Meyers.
When you deadhead hydrangeas, you aren't harming the plants at all. Removing the spent blooms triggers flowering shrubs to stop producing seeds and instead put their energy toward root and foliage development. This makes plants stronger and healthier, so by deadheading, you'll be doing your hydrangeas a favor.
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.
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.
Hydrangeas produce a “sap” that clogs their stems and blocks water from traveling up it to those gorgeous blooms. The boiling water helps to do away with the sap.
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.
Excessive acidic soil can kill or hamper the growth of plants like asparagus fern, Chinese mustard, Italian ryegrass, lavender, orchids, rosemary, tomatoes, and geranium. The roots of these plants are also not potent to absorb the nutrients added by the coffee grounds in the soil.