Renowned worldwide for their gorgeous blooms, Hydrangeas are one of the most recognizable ornamental plants in home gardens. These shrubs or vines are a backyard staple, blooming reliably and producing carpets of color. In this article, we’ll cover everything you need to know to grow the perfect Hydrangeas, from planting to care and more.
What Are Hydrangeas?
Hydrangeas are a genus of perennial shrubs or vines in the family Hydrangeaceae. Previously under the Hortensia genus, they are sometimes known as Hortensias commonly but are generally referred to simply by their genus name, Hydrangea.
Hydrangeas are incredibly popular garden plants and some of the most widely grown ornamental shrubs worldwide. They are beloved for their large clusters of flowers in different shapes and colors, making wonderful cut flowers or additions to any perennial bed.
What Do Hydrangeas Symbolize?
Hydrangeas generally symbolize grace and understanding, also conveying sincere emotion. Each color comes with its own special meaning, allowing you to tailor your message when gifting these stunning flowers:
- White: Grace, purity, vanity
- Pink: Romance, heartfelt emotion
- Blue: Regret
- Purple: Deep understanding
- Green: Renewal, rebirth
The most obvious benefit of Hydrangea plants is ornamental. The green and glossy leaves make wonderful shrubs, and the cute clusters of flowers top it all off with stunning colors. These colors change depending on the cultivar and pH in the soil, allowing you to tailor your plants to your design needs.
These plants aren’t only great for you but also for your surrounding environment. The blooms attract a wide range of pollinators to the garden, including bees, butterflies, and hoverflies. As some varieties don’t produce pollen, stick to Panicle and Climbing Hydrangeas to help out your garden friends.
Hydrangeas are also believed to have some health benefits. Some studies have shown these plants can potentially improve liver and kidney health. They are also argued to have anti-inflammatory properties and are high in antioxidants. However, there is little scientific research on its use in humans, so it’s recommended to stick to the other garden benefits.
Toxicity and Edibility
Hydrangeas are considered poisonous to humans and animals. The leaves, buds, and flowers contain cyanogenic glycoside, which can lead to nausea and vomiting when ingested. For those with sensitive skin, they can also cause minor irritation.
Ingestion is not usually fatal, especially in small amounts, but it’s recommended to keep the plants away from children and pets where possible.
Types of Hydrangeas
The Hydrangea genus contains more than 70 identified and studied species of flowering plants. But there are only a few of these commonly found in home gardens and grown worldwide:
- Bigleaf (Hydrangea macrophylla)
- Oakleaf (Hydrangea quercifolia)
- Smooth (Hydrangea arborescens)
- Panicle (Hydrangea paniculata)
- Climbing (Hydrangea anomala subsp. petiolaris)
- Mountain (Hydrangea serrata)
Each of these species contains hybrids and cultivars sporting various different colors. Most hydrangeas are white, pink, or blue, but there are also species available in purple and green. Some also have the ability to change color, determined by the pH of the soil and the plant’s progression throughout the season.
The Hydrangea Flowering Season
Most Hydrangea species flower at some point during the summer, usually from the start to the middle of the season. Exact times depend on the species and cultivar, with some flowering slightly earlier in late spring and others continuing to flower until temperatures drop in fall.
Hydrangeas can bloom continuously for around three months, again depending on the species. Some may have shorter seasons, while others bloom for even longer. External factors like temperature and zone can also impact the season, making it shorter or longer.
How Big Do Hydrangeas Grow?
Hydrangea size differs significantly by species and further by cultivar. The most popular type, Bigleaf Hydrangeas, can grow to an impressive 10 feet in height and spread with the right care, but most remain more compact.
Climbing Hydrangeas are the largest of the bunch due to their vining growth, reaching well beyond 20 feet in height if not controlled, with a spread of around 6 feet. The smallest in general size is Mountain Hydrangeas, but there are also dwarf or container hybrids within most of the species that remain compact year-round.
Suitable USDA Growing Zones and Native Range
Hydrangeas are native to Asia and the Americas, with each species originating in a different region. Most common species are from Asia, spread across China, Korea, and Japan, while the Smooth Hydrangea and Oakleaf Hydrangea are native to the North American continent.
These plants prefer moderate climates, with most growing best in USDA Zones 3-8. They tolerate colder temperatures but still require cold protection over winter to preserve the buds for flowering the following season. Some species can also be grown in warmer climates, such as H. macrophylla and H. paniculata, but most flower better in cooler weather.
Growing Hydrangeas from Seed vs Nursery Plants
Hydrangeas are usually grown from nursery plants for the quickest flowering. They are available in the fall for an early establishment or in spring with some greenery. Once planted, they should flower within the first year, but it may take longer to bloom in some instances.
You can also grow Hydrangeas from seed, but this is a far less common practice due to the difficulty of collecting seeds and the time it takes the plants to develop. Due to hybridization, the mature plants will also not match the parent. But, if you have some time, this practice makes for a fun gardening experiment.
Where To Buy Hydrangea Seeds and Starter Plants
Due to their popularity, Hydrangeas are available at most nurseries and garden centers. You can also opt to purchase online if you prefer. Prepare in advance, as specialized cultivars tend to sell out quickly.
When to Plant Hydrangeas
There are two times to plant Hydrangeas – spring and fall. Planting in fall will give the roots more time to establish, but it does mean you will need to keep the plant protected during cold winters. If planting in spring, wait until all chance of frost has passed, but don’t wait too long as high temperatures will cause the newly planted Hydrangea to struggle.
Can Hydrangeas Grow in Pots?
Hydrangeas make wonderful container plants when given enough space to grow.
Start by choosing a compact variety designed for container growth. Ensure the pot is large enough to accommodate the Hydrangea’s mature size and that it has suitable drainage holes. When choosing the best hydrangea soil, find a high-quality potting mix that drains well to avoid waterlogging.
If you want to keep your Hydrangeas in pots long-term, avoid potted Hydrangeas that can be purchased already flowering. These gifting plants are designed for short-term growth and the best blooms possible, struggling to establish or flower again when plated anywhere else.
While Hydrangeas need a healthy amount of sunlight to produce flowers, too much is not a good thing and can prevent flowering in the long run.
Most species prefer to be partially shaded – given a few hours of morning sun with some protection in the afternoon. A spot under a tree canopy that receives dappled shade is also suitable.
Avoid heavily shaded areas that prevent flowering and positions with full and intense direct sun.
When preparing beds for Hydrangea planting, choose a loamy and well-draining spot. The soil should also be rich in nutrients and organic matter for the best chances of flowering. Add compost to the soil before planting and mulch soon afterward to retain moisture and improve soil health.
If you are unsure of the pH of your soil, conduct a soil test before planting. This allows you to amend the soil when planting color-changing varieties to ensure you get the color you’re after.
Staking and Support Requirements
These vigorous shrubs generally do not need any support or staking to hold themselves up. However, vines like the Climbing Hydrangea benefit from some help to keep the leaves and blooms off the ground. Plant them near a wall or install a trellis and attach the vines to the support as they grow, allowing them to reach heights well beyond 10 feet.
Suitable or Recommended Companion Plants
Choose companion plants that appreciate a bit of shade and moist soil. These plants are all great options, adding a touch of color or greenery to your beds:
Caring for Hydrangeas
Hydrangeas are moisture lovers, needing consistent watering throughout spring and summer to flower well. Depending on conditions, they should be watered around three times per week, just as the top layer of soil dries out. If you don’t want to water as often, apply a thick layer of mulch to the base to limit evaporation.
When watering, always focus on the soil only, stopping any water from touching the leaves or flowers. This goes a long way to preventing diseases and pest problems that are difficult to manage once they occur.
Although they are not considered very heavy feeders, a regular fertilizing routine will give you the best possible blooms during the season and lengthen the lifespan of your Hydrangeas.
Fertilize once in spring with a high phosphorus fertilizer to promote flowering and again in fall before the plant needs pruning. If your Hydrangeas are not performing well, apply a low-concentration flower fertilizer just before summer kicks in.
Pruning and Deadheading Hydrangeas
Pruning and deadheading are essential maintenance tasks to keep your Hydrangeas neat and tidy. However, pruning incorrectly can have dire consequences for flowering the following season for varieties that bloom on old wood. While deadheading throughout the season, follow this guide to pruning each species correctly:
- Bigleaf: In the fall, prune back to the first set of buds.
- Climbing: Little pruning is required other than to control excessive growth and maintain shape.
- Mountain: Light prune soon after flowering
- Oakleaf: Light prune soon after flowering
- Panicle: Heavy pruning in late winter or early spring
- Smooth: Heavy prune in late winter or early spring
To manage weeds around your Hydrangeas, start with a clear planting bed. Soon after planting, add a thick layer of mulch to retain moisture and keep any weed seeds from germinating. If they do sneak through, the mulch layer will make them easier to remove.
Pull any weeds as soon as you spot them and avoid using herbicides to prevent damage to the roots and surrounding environment.
Diseases and Pests
Hydrangeas are susceptible to a few diseases thanks to their love of moisture and dense leaf growth. Look out for these common problems and tackle them as soon as you can:
- Leaf Spot
- Powdery Mildew
Pest problems are also not very likely, but it is important to deal with these issues as soon as they arise:
- Slugs and snails
Propagating and Dividing
The easiest way to propagate Hydrangeas is through cuttings. This will produce a clone of the parent plant, unlike seeds that will produce a different cultivar or may not even germinate at all.
Simply remove a cutting from a healthy branch a few inches long. Aim for newer green growth rather than old woody growth that is difficult to root. Dip the end in rooting hormone and plant in a pot with propagating soil mix. Enclose with a plastic cover to raise humidity levels and encourage new growth.
If your Hydrangea becomes overgrown, you can also split one plant into two. However, this greatly disturbs root growth and can impact your flowering for the following season, so it’s far easier to propagate via cuttings.
Transplanting hydrangeas to new locations in the garden is also possible if you’re looking to establish the plants elsewhere or find a better growing zone.
Growing Hydrangeas As Cut Flowers
Hydrangeas make wonderful cut flowers, suitable in mixed bouquets or on their own. Once flowering, it’s a simple process to trim the flower heads off and bring them indoors for display in a vase:
- Cut in the morning before temperatures rise for the longest-lasting blooms.
- Choose mature blooms that have fully opened, as new flowers won’t last long once cut.
- Trim the stem between two sets of leaves, cutting at a straight angle with sharp shears.
- Strip any leaves off the bottom half of the branch and cut again at a 45° angle.
- Place the stems in a bucket of warm water until you are ready to bring them indoors and place them in a vase.
Change the water regularly to prevent bacterial growth to keep your flowers for as long as possible. Move the vase out of the path of direct sunlight and keep it in a cool spot. If you have the space, you can keep the vase in the fridge overnight, bringing them out again in the morning.
Drying and preserving hydrangeas is another excellent way to enjoy these blooms for months to come as well.
Once the flowering season has ended, tidy up your plants by deadheading, cutting back, and pruning. Make sure you follow the proper pruning technique for your chosen species.
Depending on your zone, you may need to cover the Hydrangea in frost protection fabric to prevent damage to the buds. Mulching around the base of the plant can also keep the roots insulated during periods of intense cold.
Remove the fabric and refresh the mulch in spring once the weather warms up and wait for new green growth to appear.
Growing Hydrangeas FAQs:
Do Hydrangeas come back every year?
Hydrangeas are perennial plants, continually producing flowers year after year. External factors like zone, planting position, and care can impact the level of flowering, as well as pruning technique and fertilizing routine.
What month do you plant Hydrangeas?
Hydrangeas can be planted at two points during the year – fall and spring. In winter, the ground is too cold and hard for the roots to establish and in summer, the temperatures are too warm for these cool-loving plants.
Where do Hydrangeas grow best?
Most Hydrangea species grow best in temperature USDA Zones 3-8, preferring cooler weather to high temperatures. Some species are better at handling higher temperatures than others. They enjoy low-lying spots with well-draining soil and a bit of shade in the afternoons.
Do Hydrangeas bloom the first year you plant them?
Hydrangeas will generally bloom in the first year when planting from nursery plants. However, this is not true for all species, so you may need to wait a couple more years for the plant to establish before your plant blooms.
Can you leave Hydrangeas in the ground over winter?
Hydrangeas handle cold well and can remain in the ground over winter. They will require some frost protection to prevent any damage to buds that will produce blooms the following season.
Do Hydrangeas do well in pots?
Hydrangeas make wonderful container plants when given enough space to grow. Start by choosing a compact variety designed for container growth. Ensure the pot is large enough to accommodate the Hydrangea’s mature size and that it has suitable drainage holes. When choosing soil, find a high-quality potting mix that drains well to avoid waterlogging.
Do Hydrangeas like sun or shade?
Hydrangeas prefer partially shaded positions for the best flowering. In heavy shade, they will lack the energy to produce flowers; in full sun, they will become stressed and struggle to bloom.
How to Grow Hydrangeas – The Final Word
Growing hydrangeas can be incredibly rewarding. These beautiful ornamentals provide a kaleidoscope of color and intrigue to any garden. What’s more, they make excellent dried flowers that can be enjoyed long past the flowering season.