A 2-3” layer of mulch around the base will help keep the moisture in as well but remember, no “volcano” mulching (where you pile the mulch higher up next stem). Mulching around your hydrangea will encourage deep roots to develop, adding to winter hardiness.
To give hydrangeas their best chance at success, apply a layer of chunky mulch around the base of the plant. Decorative mulch is helpful but we recommend straw, marsh hay, or fallen leaves.
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.
Deeply water 3 times a week to encourage root growth. Bigleaf and smooth hydrangeas require more water, but all varieties benefit from consistent moisture. Use a soaker hose to water deeply and keep moisture off the flowers and leaves. Watering in the morning will help prevent hydrangeas from wilting during hot days.
To get bigger flowers, cut them all the way back
In late winter or early spring, these shrubs can be cut all the way back to the ground. Smooth hydrangeas will produce much larger blooms if pruned hard like this each year, but many gardeners opt for smaller blooms on sturdier stems.
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.
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.
A 2-3” layer of mulch around the base will help keep the moisture in as well but remember, no “volcano” mulching (where you pile the mulch higher up next stem). Mulching around your hydrangea will encourage deep roots to develop, adding to winter hardiness.
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.
Prune back stems to just above a fat bud — called a heading cut — in fall, late winter or spring. These plants have conical-shaped flower heads. I recommend leaving the dry, tan flower heads on the plant to provide some winter interest in your landscape, so I wait to prune these until late winter or spring.
Pebbles won't stop hydrangeas growing. They'll act as a mulch and help keep the soil moist. What you will find, though, is that lots of weeds love growing in them; the smaller the pebbles the worse this will be. You'd be better off mulching with a thick (six inches minimum depth) of bark chips or Strulch.
This only matters if you're trying to grow acid-loving plants like azaleas and rhododendrons. For these plants, use a mulch that releases acid, such as pine straw, pine bark (which is also high in aluminum), true cypress, and some species of eucalyptus.
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.
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.
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.
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.
But when to prune them? Prune fall blooming hydrangeas, or old wood bloomers, after they bloom in the summer. If you prune old wooded hydrangeas in fall, you are cutting off next seasons blooms. Summer blooming hydrangeas, or those that bloom on new wood, are pruned in the fall, after they stop blooming.
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.