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.
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.
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.
You need to protect your hydrangeas in the winter if your area gets freezing winter temperatures. Leaves, wood mulch and/or straw are good options to insulate your plants. Mound the mulch or leaves around your plants at least 12 inches high to protect the flower buds that will bloom early next year.
If your soil is more alkaline, your hydrangeas will be pink or even purple. According to Garden Design, adding lime or eggshells to the soil will ensure a pinker color, while adding aluminum sulfate, pine needles, or coffee grounds can give your hydrangeas the blues.
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.
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.
While many budding gardeners may be concerned that coffee grounds can attract pests, the reality is quite to the contrary. In fact, when implemented correctly, coffee grounds can be an effective way to repel certain pests such as wasps, snails, and mosquitoes.
Since coffee grounds have such a pungent and intense smell, mosquitoes do not like to come near it. Mosquitoes are repulsed by all types of coffee, whether it is fresh, used, or burnt. The most effective way to use coffee grounds for mosquito control is by burning them, as it creates a stronger aroma.
Coffee Grounds to Deter Pests
Coffee grounds are commonly used to keep animals including slugs, snails, rabbits and fire ants from eating plants in the garden, and to keep cats from treating garden beds like litter boxes.
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.
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.
Hydrangeas need direct sunlight to thrive, so plant them in a spot that has either full or partial sun exposure. Your hydrangea should also be planted away from the wind. Winds can actively dry your hydrangea plants even further, so be sure to protect your plant from the wind and hydrate it frequently.
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!
Hydrangeas that bloom on new wood can be safely pruned in late fall once the plants have gone dormant or in early spring. Next year's flower buds won't be formed until late spring the same year they bloom, so there is no risk of removing the buds if you prune in fall or spring.
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.
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.
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.
Hydrangeas grow best if they are fertilized once or twice in the summer. Although some authorities recommend special fertilizer mixes to get the maximum results, hydrangeas do amazingly well with a more relaxed approach. Either chemical fertilizers or organic matter can be used successfully.
There is one more trick up the apple cider vinegar sleeve: You can actually change the color of hydrangea flowers from pink to blue. Hydrangea flowers will be pink in alkaline soil, but change to blue in acidic soil. So, mix up some apple cider vinegar and water, and give all the acid-loving plants a treat.
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.