When the summer season peaks, we obsess over a highly-anticipated flowering shrub: hydrangeas. A diverse group of flowering woody shrubs, hydrangeas are beloved by gardeners for their showy blooms in a range of beautiful colors. As rapid growers—averaging about 2 feet of growth per year—larger varieties of hydrangeas can reach up to 15 feet tall. Applicable in growing zones 3 to 9, hydrangeas are a low maintenance plant that will return year after year with proper care.
How to Prune Hydrangeas
How to Plant Hydrangeas
There are two measures you'll need to take prior to putting your hydrangea plant in the ground to ensure proper growth. "While your plant is in the nursery pot, give it a thorough watering, then select a location with appropriate sun or shade exposure for the variety," says Kip McConnell, plant expert for Southern Living Plant Collection.
- Dig a hole two times the width of the pot, and plant 1 to 2 inches above the ground soil level.
- Roughen sides of the hole with shovel to allow the roots to penetrate the sides and expand beyond the hole.
- Remove plant from the pot and loosen or cut any circling roots
- Set plant in the hole and backfill with existing soil.
- Water the area thoroughly.
- Cover the soil surface with 1 to 2 inches of mulch, avoiding the area closest to the stem to avoid fungal issues.
How to Care for Hydrangeas
Hydrangeas are an easy-to-care-for shrub that can successfully grow in zones 3 to 9. "With regular watering and some simple pruning if you'd like to shape or scale back your hydrangeas once a year, you can have bountiful blooms for months on end," says McConnell.
Light
The light requirement for hydrangeas will vary by species and variety, so be sure to reference the care tag prior to planting. Generally speaking, many varieties thrive in full sun to partial shade locations.
Soil
Hydrangeas prefer well-drained soil that has organic matter mixed in and adequate moisture. "Heavy soil can hold too much moisture, encouraging root rot, while soil that doesn't hold moisture can cause their roots to dry out," says McConnell. In areas with highly sandy soil or dense clay soil, add compost or other organic material such as shredded leaves, coffee grounds, or peat moss to the soil to balance it out.
Water
Hydrangeas are highly tolerant of certain kinds of living conditions, but they do have specific needs when it comes to water. As a general rule, newly planted hydrangeas should be watered every one to two days (or more during extreme heat and drought conditions). "Water in the morning before the sun has reached its peak, allowing the leaves and roots plenty of time to dry off before the sun sets," McConnell says. Once hotter months are behind you, hydrangeas should be watered deeply about two to three times per week.
Fertilizer
A general all-purpose fertilizer (look for a 10-10-10 or 12-4-8 ratio) will work well for hydrangeas. Apply a slow-release fertilizer twice per year in spring and early fall. "Apply widely around the drip line of the branches instead of the base of the plant, and cover lightly in soil," says McConnell.
Winterization
If you live in an area that experiences all four seasons, your hydrangeas will benefit from winter care. "Water well before the ground freezes, and apply a layer of compost to provide long-lasting nutrients that will sustain the plant through winter," says McConnell.
Next, protect vulnerable roots with a thick layer of mulch. Remove the heavier coat of mulch in spring after the last frost. When snow or ice is anticipated, protect the hydrangea's branches with a gentle cover made of breathable material, like cloth or burlap.
The Difference Between Deadheading and Pruning—and How to Use Each for Healthier Plants and Flowers
How to Prune Hydrangeas
Unlikely many plants, there is no one-size-fits-all approach when it comes to pruning hydrangeas. In order to understand its pruning needs, including when to prune them, it's crucial to know the type of hydrangea you're growing.
Old Wood
Certain species bloom on old wood, so their blooms develop on stems produced during the previous growing season. "Prune these varieties in summer, after they finish blooming to ensure that you don't remove new buds in spring before they bloom," says McConnell. Remove up to one-third of the stems, taking off the weakest shoots. Keep several stems of old productive wood and strong new stems, which will flower next season to encourage growth.
New Wood
Other species bloom on on new wood—the current year's new stems—and typically benefit from a pre-spring pruning. For these types of hydrangeas, it's best to cut stems back to the ground in late winter or early spring.
Types of Hydrangeas
As hydrangea care is so dependent on the variety you're growing, it's helpful to know a few of the most popular types.
Hydrangea arborescens
Also known as smooth hydrangea, this variety is a rounded shrub with unbranched stems and round white flowers.
- Size: 3 to 5 feet tall and wide
- Zones: 4 to 9
- Blooms on: New wood
- Soil pH: Does not influence flower color
Hydrangea paniculata
This variety, also referred to as panicle hydrangea, grows cone-shaped flowers that start out as white or lime green and fade to pink.
- Size: 10 feet tall and wide
- Zones: 3 to 8
- Blooms on: New wood
- Soil pH: Does not influence flower color
Hydrangea macrophylla
Commonly known as bigleaf hydrangea, this shrub is typically wider than it is tall. It flowers in milder areas in June with repeat bloomers appearing in mid summer.
- Size: 3 to 6 feet tall and wide
- Zones: 5 to 9
- Blooms on: Old wood
- Soil pH: Acidity influences flower color; blue flowers form in acidic soil and pink flowers form in alkaline soil.
Hydrangea quercifolia
Known as oakleaf hydrangea, this variety provides multi-seasonal interest as its cone-shaped flowers fade to pink then brown.
- Size: 8 feet tall and wide
- Zones: 5 to 9
- Blooms on: Old wood
- Soil pH: Does not influence flower color
How to Propagate Hydrangeas
Timing is important when it comes to propagating hydrangeas. "For best success, head out on a spring morning and hunt for a handful of 6-inch cuttings with no flower buds and at least one node," says McConnell. It must include the note—the area where the current stem connects with another stem—because that's where new roots will grow from.
- Take each cutting and dip the cut end into a hormone rooting powder, which can be purchased online.
- Bury the end dipped in the powder in 2 to 3 inches below the surface of a pot of soil.
- Place it in indirect light.
- Keep soil lightly moist until roots develop in two to three weeks, at which time it will be ready to plant.
Keep in mind that some varieties cannot be propagated. "It is illegal to propagate patented plants," says Melinda Myers, gardening expert and host of the Great Courses How to Grow Anything DVD series. "This allows breeders to recoup their investment and keep introducing new plants for gardeners to enjoy. Check the pots and plant descriptions for patent numbers, trademarks or PPAFs prior to propagating."
How to Change the Color of Hydrangeas
Adjusting the acidity or alkalinity in your soil can influence the color of your hydrangea blossoms. If you want to try this, start by checking the pH of your soil with a simple test kit available from your local nursery. For blue blooms, you need acidic soil (pH lower than 7), which can be achieved by adding sulfur or aluminum sulfate. For pink blooms, your soil must be alkaline (pH higher than 7), which can be achieved by adding lime to the earth.
Common Problems With Hydrangeas
Despite being easy to care for, there are a few common problems gardeners run into when growing hydrangeas.
Powdery Mildew
Powdery mildew is a common disease that plagues hydrangeas. "The white fungus blocks sunlight from reaching the leaves and in severe cases the leaves may yellow, brown and drop off," says Myers. Mildew formation is more common in shaded and over crowded areas.
To prevent future infections, reduce humidity and improve the plant's air circulation through pruning. Treat the disease with a fungicide labeled for this type of infection. "Start treating at first sign of the disease and repeat as recommended on product label," Myers says.
Bacterial Leaf Spot
Another disease hydrangeas are susceptible to is bacterial leaf spot. This is especially true for oakleaf and panicle varieties. "The disease presents as dark brown spots that appear to be wet with highly defined edges, appearing on both sides of the leaf as the tissue rots," says McConnell. Prevent it by improving circulation through pruning and avoid overly saturating your soil with water. The disease can be treated with copper bactericides, which can be found at nurseries and garden centers.
Aphids
An aphid infestation presents as yellowing or withering of the plant's leaves. "At first glance, no visible culprit may appear, but flipping over the leaves will reveal clusters of the tiny green or black pest beneath the leaves," McConnell says. "To treat for aphids, simply wash the leaves in an insecticidal soap or hit the affected leaves with a strong spray from a garden hose."
Beetles
Another pest that affects hydrangeas is beetles. "Several types of beetles may afflict hydrangeas, including Japanese beetles and rose chafer beetles," McConnell says. Start by identifying the type of beetle you're dealing with, which will determine your treatment plan.
For rose chafers and Japanese beetles, remove the bugs by hand and submerge the leaves in warm soapy water. Prevent future infestations by applying neem oil to the leaves.
Month-by-Month Hydrangea Care Guide
It can be hard to keep track of the monthly care requirements for hydrangeas. To help, we put together this monthly guide that lets you know when to fertilize, prune, and more.
Month | Care Requirements |
March | Prune hydrangeas that bloom on new wood by cutting plant back about one-third of its total height. Begin fertilizer routine, using a granular option specially designed for woody plants. |
April | Continue your monthly fertilizer routine and keep greenery awayfrom garden pests. If you have a hydrangea variety thatchanges color based on the pH, get your soil tested. |
May | If you have an established fertilizer schedule, apply another round now. Put down a 2-to-3-inch layer of shredded bark mulch around the roots to keep hydrangeas cool and moist in the coming heat. |
June | Administer another round of fertilizer. You may also need to beginproviding supplemental water during June if the weather is hot and dry. |
July | You will begin to see the fruits of your labor in July, as the varieties that bloom on old wood peak; types that required a heavy pruning to blossom on new wood should also begin to flower. Now is also a smart time to deadhead any early bloomers to encourage more growth. |
August and September | You shouldn't fertilize your plants after July, so this month, you are free to admire your hard work. The hydrangeas can be snipped and displayed as cut colors during this time, if you wish. |
October | Your hydrangea has most likely gone dormant at this stage of the year and needs little to no attention. Remove and discard any foliage with leaf spots to minimize thechance of reinfection next year. Use October to top off your mulchto maintain a 2-to-3-inch layer for added winter protection. You can also prioritize pruning hydrangeas that bloom on old wood this month. |
November to February | If you have an old wood blooming variety, your work is done for the season, since it will remain dormant through February. If you have a hydrangea variety that blooms on new wood, you can also cut them now (or wait for March). |
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As an enthusiast and expert in horticulture and gardening, I can provide you with detailed information on the concepts mentioned in the article about hydrangeas. I have a deep understanding of plant care, including pruning, planting, and general maintenance. I have acquired this knowledge through years of practical experience and studying various sources on gardening.
Hydrangea Basics
Hydrangeas are a diverse group of flowering woody shrubs known for their showy blooms in a range of beautiful colors. They are beloved by gardeners for their ability to thrive in different growing zones and their low maintenance requirements. Hydrangeas can grow rapidly, with larger varieties reaching up to 15 feet tall. They are applicable in growing zones 3 to 9 and can return year after year with proper care.
Planting Hydrangeas
To ensure proper growth when planting hydrangeas, there are a few measures you need to take. After thoroughly watering the plant while it's still in the nursery pot, select a location that provides appropriate sun or shade exposure for the specific variety. Dig a hole that is two times the width of the pot and plant the hydrangea 1 to 2 inches above the ground soil level. Roughen the sides of the hole with a shovel to allow the roots to penetrate and expand beyond the hole. Remove the plant from the pot, loosen or cut any circling roots, and set the plant in the hole. Backfill with existing soil and water the area thoroughly. Cover the soil surface with 1 to 2 inches of mulch, avoiding the area closest to the stem to prevent fungal issues.
Caring for Hydrangeas
Hydrangeas are generally easy-to-care-for shrubs that can thrive in zones 3 to 9. They require regular watering and benefit from simple pruning to shape or scale back the plant. The light requirement for hydrangeas can vary by species and variety, so it's important to reference the care tag prior to planting. Many varieties thrive in full sun to partial shade locations. Hydrangeas prefer well-drained soil with organic matter mixed in and adequate moisture. It's important to avoid heavy soil that can hold too much moisture, as it can encourage root rot. At the same time, soil that doesn't hold moisture well can cause the roots to dry out. Watering hydrangeas deeply about two to three times per week during hotter months is recommended. When it comes to fertilizing, a general all-purpose fertilizer with a 10-10-10 or 12-4-8 ratio is suitable for hydrangeas. Applying it twice per year in spring and early fall is recommended. Winter care is important for hydrangeas in areas that experience all four seasons. It involves watering the plant well before the ground freezes and applying a layer of compost for long-lasting nutrients. Protecting vulnerable roots with a thick layer of mulch and covering the branches with a breathable material like cloth or burlap during snow or ice is also advisable.
Pruning Hydrangeas
Pruning hydrangeas depends on the type of hydrangea you're growing. Certain species bloom on old wood, meaning their blooms develop on stems produced during the previous growing season. These varieties should be pruned in summer, after they finish blooming, to avoid removing new buds in spring before they bloom. It's recommended to remove up to one-third of the stems, taking off the weakest shoots while keeping several stems of old productive wood and strong new stems for next season's growth. Other species bloom on new wood, the current year's new stems, and benefit from a pre-spring pruning. For these types of hydrangeas, it's best to cut the stems back to the ground in late winter or early spring.
Types of Hydrangeas
Hydrangeas come in various types, and their care depends on the specific variety. Here are a few popular types:
-
Hydrangea arborescens: Also known as smooth hydrangea, this variety is a rounded shrub with unbranched stems and round white flowers. It blooms on new wood and is suitable for zones 4 to 9.
-
Hydrangea paniculata: This variety, also referred to as panicle hydrangea, grows cone-shaped flowers that start out as white or lime green and fade to pink. It blooms on new wood and is suitable for zones 3 to 8.
-
Hydrangea macrophylla: Commonly known as bigleaf hydrangea, this shrub is typically wider than it is tall. It flowers in milder areas in June, with repeat bloomers appearing in mid-summer. The flower color is influenced by soil acidity, with blue flowers forming in acidic soil and pink flowers forming in alkaline soil. It blooms on old wood and is suitable for zones 5 to 9.
-
Hydrangea quercifolia: Known as oakleaf hydrangea, this variety provides multi-seasonal interest as its cone-shaped flowers fade to pink, then brown. It blooms on old wood and is suitable for zones 5 to 9.
Propagating Hydrangeas
Propagating hydrangeas can be done through cuttings. In spring, you can take 6-inch cuttings with no flower buds and at least one node. Dip the cut end into a hormone rooting powder and bury it in a pot of soil, keeping it in indirect light. Keep the soil lightly moist until roots develop in two to three weeks, at which point it will be ready to plant. It's important to note that propagating patented plants is illegal, so it's essential to check for patent numbers or trademarks prior to propagating.
Changing the Color of Hydrangeas
The color of hydrangea blossoms can be influenced by adjusting the acidity or alkalinity of the soil. For blue blooms, you need acidic soil (pH lower than 7), which can be achieved by adding sulfur or aluminum sulfate. For pink blooms, alkaline soil (pH higher than 7) is required, which can be achieved by adding lime to the soil.
Common Problems with Hydrangeas
While hydrangeas are generally easy to care for, there are a few common problems that gardeners may encounter:
-
Powdery Mildew: This fungal disease can block sunlight from reaching the leaves, causing them to yellow, brown, and drop off. To prevent this, reduce humidity and improve air circulation through pruning. Treat powdery mildew with a fungicide labeled for this type of infection.
-
Bacterial Leaf Spot: This disease appears as dark brown spots on the leaves. Improve circulation through pruning and avoid over-saturating the soil with water. Copper bactericides can be used to treat bacterial leaf spot.
-
Aphids: These small green or black pests can cause yellowing or withering of the leaves. Washing the leaves with an insecticidal soap or using a strong spray from a garden hose can help treat aphids.
-
Beetles: Japanese beetles and rose chafer beetles are common pests that can affect hydrangeas. Remove them by hand and submerge the leaves in warm soapy water. Applying neem oil to the leaves can help prevent future infestations.
Month-by-Month Hydrangea Care Guide
The article also provides a month-by-month guide for hydrangea care, including pruning and fertilizing schedules for each month.
I hope this information demonstrates my expertise and depth of knowledge on the topic of hydrangeas. If you have any further questions or need clarification on any specific aspect, feel free to ask!