With immense flower heads, hydrangeas flaunt an old-fashioned charm in summertime that’s hard to resist. While these flowering shrubs are low-maintenance, proper care will keep them blooming. Our Hydrangea Guide provides summer plant care tips for all you need to know about growing hydrangeas—from watering to fertilizing to pruning to winter care.
Unrivaled in the shrub world for beautiful flowers, these elegant plants are easy to cultivate, tolerate almost any soil, and produce abundant blooms. Colors beguile with clear blue, vibrant pink, frosty white, lavender, and rose blossoms—sometimes all blooming on the same plant!
Hydrangeas are excellent for a range of garden sites from group plantings to shrub borders to containers. Varieties abound (every year, it seems, breeders present us with more options!), and gardeners’ expectations of bloom size and color are boundless. To know how your hydrangea will grow, pay attention to the types, defined below. When you know what to expect, delights will be magnified.
Enjoy this ode to the beautiful of hydrangeas and learn how to grow hydrangeas in our guide below.
WHEN TO PLANT HYDRANGEAS
Plant in spring after the last spring frost or in fall before the first fall frost. See local frost dates.
Plant before the heat of summer arrives.
WHERE TO PLANT HYDRANGEAS
Most hydrangeas will thrive in fertile, well-draining soils that receive plenty of moisture. Add compost to enrich poor soil.
Generally, hydrangeas prefer partial sun. Ideally, they will be given full sun in the morning, with some afternoon shade to protect from the hot midday sun. This is especially true for the Bigleaf hydrangea (H. macrophylla), which is prone to wilting. Some varieties are more tolerant of full sun.
Space hydrangeas anywhere from 3 to 10 feet apart, depending on type.
HOW TO PLANT HYDRANGEAS
Dig a hole as deep as the root ball and 2 to 3 times as wide.
Set the plant in the hole and fill it half full with soil. Water. After water is absorbed, fill the rest of the hole with soil.
Water thoroughly again.
HOW TO GROW HYDRANGEAS FROM CUTTINGS
Hydrangeas can easily be grown from cuttings. They root readily and the process makes for a great lesson in propagation. Here’s how to do it:
On a well-established hydrangea, find a branch that is new growth and that has not flowered. New growth will appear lighter in color than old growth, and the stem will not be as rigid.
From the tip of the branch, move 4 to 5 inches down and make a horizontal cut. Make sure that there are at least 3 to 4 pairs of leaves on your cutting.
Remove the lowest pair of leaves from the cutting, trimming them flush to the stem. Roots grow more easily from these leaf nodes, so if you can afford to remove more than one pair of leaves, do so. Be sure to keep at least 2 pairs of leaves at the tip end of the cutting, though.
If the remaining leaves are quite large, cut them in half, removing the tip-half. This prevents the leaves from hitting the sides of the plastic bag you will place over the cutting later on (to keep the humidity up).
(Optional) Dust the leafless part of the stem with rooting hormone and an anti-fungal powder for plants (both available at a local hardware or garden store). This will encourage rooting and discourage rotting.
Prepare a small pot and fill it with moistened potting mix. Plant the cutting in the soil, sinking it down to the first pair of remaining leaves. Water lightly to get rid of any air gaps around the stem.
Cover the entire pot loosely with a plastic bag. Make sure the bag isn’t touching the leaves of the cutting, otherwise the leaves can rot. (Chopsticks or something similar can be used to prop up the bag and keep it off the leaves.)
Place the pot in a warm area that’s sheltered from direct sunlight and wind.
Check on your cutting every few days to make sure that it isn’t rotting and only water again once the top layer of soil is dry. With luck, the cutting should root in a few weeks! (Check by gently pulling on the cutting; if you feel resistance, roots have formed.)
For the first year or two after planting and during any drought, be sure hydrangeas get plenty of water.
Water at a rate of 1 inch per week throughout the growing season. It’s better to deeply water 3 times a week than sprinkle water in a shallow manner. This encourages root growth.
Bigleaf and smooth hydrangeas require more water, but all varieties benefit from consistent moisture.
Leaves will wilt if the soil is too dry, and flowering will be hampered by a lack of water.
Use a soaker hose to water deeply and keep moisture off the flowers and leaves.
It’s best to water in the morning to prepare hydrangeas for the the heat of the day and to avoid disease.
Add organic mulch underneath your hydrangeas to help keep the soil moist and cool, add nutrients over time, and improve soil texture.
If your soil is rich, you may not need to fertilize hydrangeas. Too much fertilizer encourages leafy growth at the expense of blooms. The best way to determine your fertility needs is by using a soil test.
Apply fertilizer based on your specific hydrangeas. Each variety has different needs and will benefit from different application timing.
Bigleaf hydrangeas can benefit from several light fertilizer applications in March, May and June.
Oakleaf and panicle hydrangeas do best with two applications in April and June.
Smooth hydrangea plants only need fertilization once, in late winter.
In the fall, cover plants to a depth of at least 18 inches with bark mulch, leaves, pine needles, or straw in the fall. If at all possible, cover the entire plant, tip included, by making cages out of snow fencing or chicken wire, and loosely filling the cages with leaves. (Do not use maple leaves, as they tend to mat when wet and can suffocate the plant.)
HOW TO CHANGE THE COLOR OF HYDRANGEA FLOWERS
It is possible to change the flowers’ colors, but not instantly. Color correction takes weeks—even months. Wait until the plant is at least 2 years old to give it time to recover from the shock of its original planting. Also note that it’s easier to change blue flowers to pink than pink to blue.
It’s not every hydrangea that changes color. The color of some Bigleaf hydrangeas (H. macrophylla)—especially Mophead and Lacecap types—and H. serrata cultivars change color based on the soil pH.
Acidic soils with a pH of less than 5.5 produce blue flowers; soils with a pH greater than 5.5 produce pink flowers. White flowers are not affected by pH.