How to Grow and Care for Hydrangeas
Homeowners can add bursts of colorful blooms to their gardens by planting hydrangeas. Many types of hydrangeas can thrive in your yard with regular watering and seasonal pruning, from small shrubs with delicate flowers to large bigleaf varieties.
Find your favorite hydrangea varieties, and see how to care for them throughout the blooming seasons in this guide. Plus, learn how to make them bloom in your favorite color.
How to Choose Hydrangea Varieties
Hydrangeas are a popular flowering shrub, and home gardeners can choose from a wide range of species. All hydrangea species have similar watering, soil, and sunlight requirements, but they require different pruning during their seasonal cycles. Consider your preferred flowers and size as well as your local climate to determine the best hydrangeas for your garden.
- Bigleaf (hydrangea macrophylla): This shrub can grow up to 10 feet tall and has large, 6-inch leaves. It goes by multiple names, such as mop head, lacecap, and bigleaf. If you want large hydrangea bushes and the ability to control the bloom’s color between blue and pink, this is a lovely garden addition. These hydrangeas thrive in full sun to partial shade.
- Panicle (hydrangea paniculata): Panicle hydrangea shrubs grow even larger across their lifetime, reaching up to 15 or 20 feet. Every year, you’ll see fresh blooms on the new stems. As the seasons pass, you’ll see the new cone-shaped flowers transition from bright white when the plant is young to a darker and darker pink. These hydrangeas require at least four hours of direct sunlight per day.
- Oakleaf (hydrangea quercifolia): This midsize shrub grows to 7 feet and has white, pink, purple, or red cone-shaped flowers. These hydrangeas get their name from their leaf shape, which is similar to the leaves on an oak tree. They thrive in full sun in U.S. Department of Agriculture (USDA) hardiness zones 4, 5, and 6, but they need afternoon shade in higher zones.
- Smooth (hydrangea arborescens): If you love miniature shrubs or don’t have space for a sprawling hydrangea plant, smooth hydrangeas may be the perfect fit. They only grow up to 5 feet and can even thrive in pots. Plant or place hydrangeas in partial shade for best growth. You’ll see lacy, flowering bunches in whites and pinks.
Many gardeners select hydrangeas based on their preferred size, flower shape, and bloom color. You can also select your plants based on their budding schedule. Both bigleaf and oakleaf hydrangeas bud in summer and fall for the upcoming spring, while smooth hydrangeas bud in spring. As hydrangea plants mature, they grow new lengths of stem. Panicle hydrangeas bloom on that new stem growth throughout the years.
Pro tip: Before you buy your new hydrangea shrub, see what USDA zone your home is in. This determines what types of plants will grow best in your garden and can help you choose your overall landscape design.
Where to Plant Hydrangeas
Each hydrangea variety can survive in direct sunlight, but most do better in dappled sunlight or partial shade. Whenever possible, plant your hydrangeas near tall, deciduous trees that provide dappled sunlight and shade from the hot afternoon sun. This strikes a good balance between sunlight, which encourages flower growth but can dry out the plant, and shade, which can decrease flower production but help keep the plant hydrated.
Plant your hydrangeas on the north- and east-facing sides of your property, where they’re shielded from both the hot summer sun and winter sunlight that can trick plants into budding early.
The right soil conditions also make a difference for your hydrangeas. While the plants can grow in sandy or even loamy soil, they generally prefer humus-rich and well-draining soil.
If you plant bigleaf hydrangeas, you can control the color of the blooms by managing the soil’s pH: Acidic soil levels (with a pH below 6.0) lead to blue flowers, and alkaline soils (with a pH above 7.0) produce pink flowers. You can test your soil with pH strips and treat the soil accordingly to produce the results you prefer.
Hydrangeas can be planted directly in the ground or in pots, even during winter. Be sure to insulate the pots with burlap wrapping. If your property’s soil is nutritionally poor, a layer of mulch or compost can help replenish the missing nutrients. However, a light application of compost in the spring is all you need.
How to Water and Fertilize Hydrangeas
Hydrangeas need deep and frequent watering cycles. Water them once or twice per week with a heavy hand: The water needs to reach deep below the soil to hydrate the roots, so water them until the soil is thoroughly saturated. Maintain this water cycle throughout the growing season. If you’re in a high plant hardiness zone in the southern United States, monitor your hydrangeas carefully during the height of summer. If the soil 4 inches below the surface feels dry, water the plant heavily.
Here are some signs you’re underwatering your hydrangea bushes:
- Brittle leaves and flowers
- Drooping and falling leaves
- Dry soil below the surface
- Yellow or brown leaves (though yellow leaves can also indicate overwatering)
If your garden beds have lots of nutrients in the soil, you won’t need to treat them with fertilizers. If your soil is nutritionally deficient, apply organic fertilizers in the spring. Avoid nitrogen-heavy fertilizers, as they can make your shrubs produce fewer blooms.
How to Change Hydrangeas’ Flower Color
Home gardeners of all experience levels can turn their gardens into a rainbow of vibrant blooms by controlling the soil’s acidity or pH. Bigleaf hydrangeas produce blue blooms in acidic soil and pink blooms in alkaline soil. Look for bigleaf hydrangea varieties such as Cityline, Endless Summer, and Lacecap.
To lower the pH and make the soil acidic, mix together 1 pound of aluminum sulfate and 5 gallons of water. Then, water the soil around the plant’s drip line. Be careful with aluminum sulfate: It can injure most plants besides hydrangeas. To increase the pH and create alkaline soil, sprinkle at least 3 cups of lime around the base of the plant; it’s better to do too much than too little. Because of natural pH variations in the soil, you may have blooms that are pink, purple, and blue across every shrub.
How to Prune Hydrangeas
One of the most challenging aspects of hydrangea care is perfecting the pruning schedule, especially because different hydrangea species should be pruned at different times. Most varieties, including mopheads, oakleafs, mountain, and climbing hydrangeas, should be pruned after they flower in the late summer. Panicle and smooth hydrangeas should be pruned in the early spring before spring growth begins.
Base your pruning schedule on where new blooms sit. If the flowers appear on new growth every year, then they need to be pruned before the spring growing season. If they bloom on old growth, then prune them before the end of the summer growing season.
You can also deadhead your hydrangeas, or prune away spent and fading blooms. If you see spent blooms throughout the spring, summer, and early fall growing seasons, clip them off with a pruner right above the first set of leaves below the bloom. This encourages the plant to focus on foliage and root growth.
How to Troubleshoot Problems
Hydrangeas are great for both new and experienced gardeners because they’re resilient perennials that can thrive in a wide array of sunlight conditions and hardiness zones. But like all plants, they can experience pest problems and diseases.
The best way to keep damage at bay is with preventive care. Prune away dead stems and blooms to mitigate rot or disease, and place mulch around your plants before the winter so they stay protected during the cold months.
Aphid Infestation
One problem that can impact even diligently maintained hydrangeas is aphid infestation. Aphids are small, green, sap-sucking insects. Having a small number of aphids can help your plants by inviting ladybugs and other helpful insects into your garden, but large swarms can damage your plants’ health.
If you see many aphids on your plants, hose them off and gently wash the affected area with an insecticidal soap. You can also spray the soil with a diluted soapy solution to deter new aphids and vine weevils from infesting the plant.
Mildew
White, gray, or yellow spots on your hydrangea’s leaves may indicate powdery mildew. To keep this fungal infection at bay, stop fertilization treatments, remove fallen leaves (especially infected ones), and prune back your plant to remove damaged stems and shoots.
Wilting
Wilting can impact all plants in your garden. Wilting can indicate either underwatering or overwatering. Monitor the soil conditions and track rainstorms in your area to ensure your shrubs receive the right amount of water, and the wilt should correct itself.
Our Recommendation
Hydrangeas are a bright and colorful addition to any garden. If you’d like to grow your own hydrangeas, select a variety that thrives in your region’s hardiness zone classification. We recommend planting your hydrangeas at north- and east-facing sites that offer a good mix of direct sunlight and protective partial shade. As the plant acclimates, water the growing hydrangeas deeply, prune away deadhead and unnecessary old wood, and monitor the soil conditions for vibrant, healthy growth throughout the seasons.
Reach out to your local extension office for advice about your specific region. These offices are county programs staffed by experts from local universities. They offer residents and businesses advice about crops, plants, and regional growing conditions.
Hydrangea FAQ
What is the best hydrangea for full sun?
The best hydrangea for full sun conditions is panicle hydrangeas. These shrubs bloom in the summer and produce large white flowers that turn pink or red as the summer ends. They can handle both morning sun and afternoon sun.
When should you prune hydrangeas?
You should prune hydrangeas based on the best practices for each specific variety. Prune panicle and smooth hydrangea shrubs in the late winter or early spring. Most other varieties should be pruned at the end of the summer growing season.
How do I make hydrangea flowers blue?
You can make bigleaf hydrangea flowers blue by planting them in acidic soil. Increase the soil’s pH around planted hydrangeas by spreading a mixture of heavily diluted aluminum sulfate around the base.
What causes hydrangea leaves to turn yellow?
Several things can turn hydrangea leaves yellow. Diseases, overwatering, nutrient deficiency, and even applying fertilizers with too much nitrogen can yellow the leaves.
How much water do hydrangeas need?
Hydrangeas need approximately 1 inch of water every week. Heavily water the shrubs once or twice a week; the soil should be saturated but not waterlogged.
