Hydrangeas vs. Rhododendrons: Which is the Better Choice for Your Garden?

Deciding to plant a large flowering shrub can be a big commitment. Hydrangeas and rhododendrons are both wonderful choices, but which one will work best in your space? Gardening expert Melissa Strauss unpacks the needs of each to help you make the best choice.

A close-up of pink Hydrangeas with vibrant, fluffy petals surrounded by lush green leaves, planted in a park alongside other verdant plants.

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Rhododendrons and hydrangeas are among the most popular flowering shrubs in the United States. With their beautiful flowers and attractive foliage, both of these plants are certain to please any gardener. 

Both plants flower in a wide variety of colors, and the flowers of both are large and striking. They both make excellent landscape elements, noise screens, and privacy hedges with their dense, attractive foliage. There are many similarities between them, and also a few differences.

If you’re having some difficulty deciding which of these shrubs is right for your landscape, we are here to help! I’d love to walk through the characteristics of these two plants. That way you can make an informed decision and choose the right shrub for your garden.

The Short Answer

Hydrangeas and rhododendrons have very similar care and environmental needs. There are varieties of hydrangea that are more tolerant of cold temperatures and can thrive as far north as Zone 3. Rhododendrons have a more limited climate range, and are a bit less tolerant of heat, as well.

Rhododendrons are evergreen, making them a great choice for year-round interest in the garden. If you’re looking for an evergreen, this is the obvious choice. Some types of hydrangeas are slightly more tolerant of sun exposure as long as you meet their rather substantial moisture needs.

For the most part, the decision between these two plants is a personal preference. Either one is a beautiful addition to the landscape. They have similar levels of maintenance and needs.

The Long Answer

A close-up of Azaleas with delicate pink blossoms against a backdrop of vibrant green foliage and large trees, set against a lush green lawn.
Rhododendrons and hydrangeas both have long bloom times and life spans.

It’s difficult to make a bad choice between these two beautiful shrubs. They both grow in a wide range of climates, and there are many varieties of each to suit different light conditions. Whether you are looking to fill a space in full sun or partial shade, there is a rhododendron and a hydrangea to meet those needs. Both plants tolerate hard pruning as a means of rejuvenation. 

Choosing the best plant for your garden landscape doesn’t have to be a stressful decision. Both of these plants will bring years of enjoyment. If properly cared for, they are both long-lived, although rhododendrons do steal this category. They can live as long as 50-80 years! Hydrangeas have an average lifespan of 10-20 years, although I have known them to live quite a bit longer.

Some varieties of rhododendrons can grow very large, reaching 20 feet or taller. Hydrangeas tend to stay lower to the ground, topping out around eight feet, unless they are climbing. Eight feet is still a fairly large plant. Hydrangeas will spread about as wide as they are tall, perhaps slightly wider. Rhododendrons will typically be slightly taller than they are wide. There is a wide range of sizes where both are concerned, so it shouldn’t be difficult to find one to suit your space.

I would love to help you make this important decision, so I’ve compiled some information on both plants. Let’s discuss the needs of each. Then, if you still need to decide which you prefer, there is no harm in planting one of each!

Hydrangeas

A close-up of a Hydrangeas plant showcasing vibrant blue and pink flowers against a backdrop of lush green leaves.
These flowers are favored in floristry.

Hydrangeas are enchanting shrubs with large clusters of blooms in spring and summer. Their broad, attractive foliage makes a wonderful backdrop for other plants, even when they are not in bloom. But truly, the flowers are an absolute masterpiece. These shrubs produce large, rounded clusters of blooms in shades of pink, blue, violet, green, cream, and even red.

These stunning flowers are popular in floristry, especially for weddings. They are large and dramatic and symbolize unity and togetherness. On or off the plant, they are unmistakable and undeniably beautiful. 

Hydrangea shrubs are hardy in Zones 3-9, making them the more versatile of the two. They will grow to heights between four and 12 feet tall. Let’s talk about their needs to determine if they are right for your garden. 

Soil Needs

A close-up of hands wearing gloves planting a young rooted cutting of a panicle Hydrangea into dark soil, surrounded by various other green plants in the garden.
Avoid planting in areas that don’t drain well.

Hydrangeas like water, but they don’t tolerate wet feet. The soil where you plant this shrub must have proper drainage. They also prefer an acidic pH, so rich, loamy soil with lots of organic matter is ideal. 

If drainage is a concern, work plenty of organic compost into the soil. In general, don’t plant one of these in a spot that doesn’t drain properly. You can temporarily improve the drainage in an area, but in the long term, it’s likely to return to its original state. 

Exposure

A close-up of Hydrangea Paniculata 'Renhy' Vanilla Strawberry with large cone-shaped clusters of white flowers turning pink, surrounded by vibrant green leaves.
Morning sun is gentler for hydrangeas in warm climates.

The amount of sun your plant prefers depends on the type of hydrangea, as well as the climate you live in. In very hot climates, nearly all types will need partial sun. Oakleaf hydrangeas prefer some shade in the afternoon in warm climates and full sun in cooler climates. Panicle hydrangeas vary by variety. Climbing hydrangeas are perhaps the most sun tolerant. Some thrive in full sun, while others prefer partial shade. 

Overall, in warm climates, they need some sun, but not all-day exposure. They should have some protection from the hot afternoon sun. Morning exposure is gentler and accomplishes the same purpose. Make sure to research the specific variety you want to plant to get a clearer picture of how it will perform in your space.

Water

A close-up of a man watering Hydrangea plants in a garden with light purple and pink flowers, using a watering hose, showcasing lush green foliage around the plants.
Drooping leaves and wilted flowers indicate a thirsty plant.

Hydrangeas are moisture-loving plants as long as their roots don’t sit in soggy soil. Your newly planted shrub will need watering on a daily to every other day basis. Once established, the amount of water you give your plant will hinge on the time of year and the amount of rain your plant gets. 

When a hydrangea is thirsty it will let you know with drooping leaves and wilted flowers. Water your plant at the ground level rather than overhead. These shrubs are susceptible to fungal disease, so try to keep the leaves dry. If you live in a very dry climate, you’re likely to spend a lot of time watering this plant. 

Maintenance

A close-up of vibrant Hydrangea flowers in blue and pink hues, surrounded by lush green leaves, with more Hydrangea plants in the background.
Pruning old wood-blooming plants is challenging.

Hydrangeas need a moderate amount of fertilizer. You should fertilize in spring and summer, no more than once per month. Use a balanced fertilizer or one that contains more nitrogen

These shrubs will bloom more if you deadhead them, so pruning is a consistent practice. Old wood-blooming plants are tricky when it comes to pruning. Prune these immediately after blooming, so the plant will set new buds for the following year. New wood bloomers are more flexible. You can prune them in early spring before they set buds or in late summer after they finish blooming. 

Rhododendrons

A close-up of Red Rhododendron Romany Chai Group in full bloom, featuring striking red flowers contrasted against deep green foliage.
These shrubs thrive despite harsh summers.

Rhododendrons are another group of gorgeous, colorful, flowering shrubs. They are often the first plants to bloom in spring, as a result. Hydrangeas bloom in late spring and summer. 

These shrubs will grow in Zones 4-8, although the summers in Zone 8 tend to be a bit harsh for them. Nonetheless, some species can handle it as long as they have some shelter from the intense summer sun. 

Rhododendrons are slower growing, and reach their final heights between three and 20 feet tall. It takes a while to get to that peak height, though. It can take up to ten years for these plants to mature

These shrubs produce large clusters of trumpet-shaped flowers in shades of red, pink, purple, white, coral, and sometimes yellow. The blooms are attractive to pollinators, which I find to be an advantage. Let’s look at the needs of these evergreen shrubs.

Soil Needs

A close-up of Azalea plants showcasing light purple flowers amidst lush green foliage in a garden setting.
Annual top dressing enhances growth.

Rhododendrons prefer acidic soil that is rich in organic matter and nutrients. They grow well in wooded areas where there is an abundance of leaf litter and other decaying organic matter on the ground. 

Add plenty of compost to the soil when planting this shrub, and give it some extra top dressing on a yearly basis. Drainage is also an important factor. These plants need proper drainage, as they won’t tolerate soggy roots. 

Exposure

A close-up of a Hydrangea plant showcasing pink clustered flowers against large, green textured leaves.
Proper research on sunlight requirements prevents leggy shrubs.

There is a wide range of species with different exposure needs, from full sun to full shade.  For the most part, these plants need some sunlight if you want to see them bloom. However, if you have a shaded yard, you will find rhododendrons that will thrive in these conditions

Too much shade may cause some shrubs to become leggy, and not produce flowers. Make sure to research the specific type you purchase when determining the amount of sunlight it needs. 

Water

A close-up of Rhododendron Catawbiense Grandiflorum with purple flower buds and glossy green leaves.
Deep watering prevents soggy soil and root fungus.

The shallow root systems of these plants make watering a bit tricky. Because they are shallow, they tend to dry out quickly in the heat of summer. However, they will not tolerate constantly moist soil.

Newly planted rhododendrons will need deep watering twice weekly. Once established, you can decrease this to once per week. In times of heat and drought, go back to twice-weekly watering. Slow but deep watering is best to help these shrubs absorb all they need while avoiding soggy soil and root fungus. 

Maintenance

A close-up of a rhododendron plant featuring vibrant blue flowers in full bloom, contrasted against lush green leaves with a glossy texture.
Prune immediately after blooming to prevent re-seeding.

Rhododendrons don’t need fertilizer unless the soil is lacking in nutrients. In nutrient-poor soils, fertilize rhododendrons after they bloom in spring with a balanced organic feed. In colder areas, don’t fertilize in the summer. Doing so encourages new growth late in the year. New growth is more susceptible to cold damage.

You can prune this plant any time of year, depending on your purpose. Prune immediately after blooming to discourage re-seeding and encourage new growth. If you want to reduce the size of your plant, you should prune in late winter. Be advised, though, that this will reduce blooming, possibly altogether. Clean-up pruning can happen at any time of year to remove dead or damaged foliage. 

Final Thoughts

Both of these shrubs make a beautiful choice in the landscape. They both produce stunning floral displays and attractive foliage. The decision truly comes down to personal preference. With a few considerations of sun exposure and climate, most varieties of both plants have similar needs. They are both versatile and require a moderate amount of maintenance.  

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