Homemade compost is a great source of slow release nutrients for hydrangeas. Either top dress the soil beneath your plants with your compost and water well or brew up a batch of compost tea and give your plants a deep drink of it. You can repeat your application of compost tea in 2 to 3 weeks.
Hydrangea plants can benefit from well-balanced, slow-release organic fertilizer. Some of the best fertilizers for hydrangeas are Espoma Holly-Tone, Dr. Earth Premium Gold, and Happy Frog Fruit & Flower.
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.
A good all-purpose 12-4-8 or 10-10-10 composition will provide all the fertilizing hydrangeas need. Either a chemical source or organic matter can be used successfully. Applying a once a year slow-release chemical formulated for shrubs and trees is the simplest solution to hydrangea care and feeding.
For hydrangeas planted in ground.
For optimal growth, bloom production, and quality, fertilize three times: In early spring when plants are just leafing out. In early May to boost their flower production for summer. In late June/early July to help your plants finish the summer strong.
A pH of 7 is neutral, and household vinegar has a pH of around 2.4 (which is quite acidic). The theory is, applying diluted vinegar to the soil will lower the pH enough to change the color of your hydrangea blooms. This strategy will make the soil more acidic, but not for long!
Start adding coffee grounds to the soil surrounding your hydrangeas in late fall. Sprinkle them around your hydrangeas, but be sure to work them into the soil to help eliminate any off-putting smell. You do not need to do this process often–just two to three times per year should be sufficient.
Hydrangeas generally begin blooming in the later summer and early autumn. They'll sprout leaves in the Spring months, but the blooms likely won't appear until July. So the best time to begin treating your hydrangeas with coffee grounds is in early summer before blooms appear.
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 provides various minerals, including copper, calcium, and iron, to supplement common nutrient deficiencies.
Supply the Right Amount of Water. Along with planting them in the right place, properly watering your hydrangeas is essential to bigger and better blooms. "Hydrangeas should be watered deeply several times per week to encourage deep root growth," says Enfield.
However, slow-release is certainly not the only way to fertilizer hydrangeas. A less expensive fast release fertilizer such as a 10-10-10 will work just as well if applied twice during the summer.
"A compost pile would be the natural fertilizer I would strongly recommend," says Kemper. To make compost, take all your scraps (like eggshells, fruit peels, and coffee grounds) and put them into a pile with leaves, sticks, and other organic debris.
A Little Goes a Long Way. Baking soda is the secret, but keep in mind that a little bit does go a long way. To apply it to your wilted hydrangeas, mix 1 tablespoon of baking soda into 2 quarts of water. Stir to be sure the baking soda thoroughly dissolves.
Don't waste your grass clippings either - they are a good source of nitrogen, with an NPK ratio of 4:2:1 (4 % nitrogen, 2 % potassium, 1 % phosphorus). Fill a 5 gallon bucket with grass clippings. Fill the bucket with water and leave for 3 days. Mix 1/4 cup of Epsom salt with two cups of urine.
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.
Water your hydrangeas in the morning before the heat of the sun is strong enough to quickly evaporate soil moisture. Try to avoid watering at night, which can encourage mold and mildew as the moisture sits through the cool night. Water your hydrangeas through the growing season as well as in late fall.
In most cases, the grounds are too acidic to be used directly on soil, even for acid-loving plants like blueberries, azaleas and hollies. Coffee grounds inhibit the growth of some plants, including geranium, asparagus fern, Chinese mustard and Italian ryegrass.
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.
If your hydrangeas do get infected, you have several options, including compost tea, hydrogen peroxide, garlic oil, or liquid kelp. You can also apply the fungicides chlorothalonil or thiophanate-methyl.
Use vinegar diluted with water in a ratio of 20 parts water to one part apple cider vinegar. Water the plants along their base. Try not to get the vinegar-and-water solution onto the leaves, because it can burn the foliage.
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.
15-10-10 Flower Fertilizer
Great for Hybrid Tea, Old Fashion & Landscape Roses. They're like Vitamins for your Landscape!
Learning how to fertilize hydrangea shrubs is equally as important as the type of fertilizer chosen. Apply a slow-release chemical for shrubs and trees once a year. Depending on the variety, a balanced time-release fertilizer can be applied a few times a year, in spring and early fall.