How to Plant, Grow, and Care for Oakleaf Hydrangeas
Thinking of adding some oakleaf hydrangeas to your garden this season, but aren't sure where to start? This species is a favorite amongst many gardeners, so it's important to start off on the right track if you are adding them to your garden this season. In this article, gardening expert and hydrangea enthusiast Jill Drago walks through how to plant, grow, and care for Oakleaf Hydrangeas.
In a sea of blue mophead hydrangeas and lush round leaves, oakleaf hydrangeas can really stand out. Their ornate leaves and long panicle flowers add texture to any garden. Hydrangea quercifolia is easy to establish in your garden and easy to maintain for years to come.
While they may not be quite as popular as hydrangea paniculata or hydrangea arborescens, this particular species can add plenty of garden interest with their beautiful foliage and uniquely shaped blooms.
If this plant is new to you, read along for some interesting history on the plant as well as tips to help you become a successful oakleaf hydrangea grower! Ready to learn more? Let’s dig in!
Oakleaf Hydrangea Overview
Plant Type Flowering Shrub
Pests Aphids, Deer, Spider mites
Exposure Partial sun to shade
Maturity date 1-5 years
Growth rate slow to moderate
Soil type well draining
Native Area South East United States
Plant Spacing 2- 12 feet depending on variety
Attracts pollinators, seeds attract songbirds
Hardiness zones 5-9
Plant with Fern, Hosta, Lilyturf
Planting depth Depth of root ball
Watering requirement moderate to high
Don’t plant with N/A
Height 2-12 feet depending on variety
About Oakleaf Hydrangea
It is hard to mistake an oakleaf hydrangea. Its leaves are very unique compared to other species. Instead of the rounded leaves of its relatives, their leaves are lobed and very much resemble that of an oak tree. The flowers are formed in panicles and can reach 10 inches long and even longer in some cases.
Panicle flowers are branched flower heads. Meaning that there are many stems, each with one flower. All of these stems grow together on what is called a raceme and it creates a panicle flower which takes on a cone or pyramidal shape. They are made up of attractive sepals, or sterile flowers, that cover the mass of fertile flowers that are closer to the stem of the plant.
This species is native to the southern regions of the United States. These plants gained popularity in the 1700s and were planted at Geroge Washington’s Mount Vernon as well as Thomas Jefferson’s Monticello.
Both of these Founding Fathers purchased these Hydrangea quercifolia seeds from a man named William Bartram who owned a nursery in Philadelphia. The Bartram family is considered one of the first botanist families of America. William Bartram discovered the oakleaf hydrangea in 1776 in Georgia.
Without the discovery of the oakleaf hydrangea as well as the smooth hydrangea (also discovered by the Bartram family) the popularity of the Asian hydrangea may never have taken hold in the United States. Many of the popular species such as bigleaf hydrangeas, panicle, and climbing hydrangeas are native to China or Japan.
Because this species is native to the United States it is a bit more of a vigorous grower here. It is native to the southern portion of the country making it a great option for warmer hardiness zones.
This species can be easily propagated by taking cuttings, or by layering them in your garden similarly to its other species. However, they can also be grown from seed, and have high germination rates.
You can collect seeds by collecting flowers that are beginning to dry out and storing them in a bag until the seeds shake loose. These seeds should be planted quickly, their germination success correlates to the freshness of the seeds.
Usually, most gardeners opt to transplant from cuttings, or just purchase them from a local garden center as a transplant.
How to Plant
Oakleaf hydrangeas are available at most nurseries and garden centers. Most of these garden centers will have many different varieties available in all sorts of sizes. Select an area in your garden with morning sun and afternoon shade that has enough room for this species once it is full-grown. You can find that information on your plant tag.
They are best planted in the spring when the ground has thawed, or in the fall. Once its been planted, be sure to keep it watered until it is well established.
How to Grow
When growing any species of hydrangea, it’s important to make sure you provide optimal growth conditions in all aspects. This means giving it the right amount of light, water, fertilizer and making sure the soil is properly balanced. Let’s take a look at the most important aspects of growth, care, and maintenance.
If you have a space in your garden that receives morning sun and afternoon shade, this is the perfect plant for that space. They will tolerate a little bit more shade than some of their other relatives, however you may be sacrificing some of the blooms you would see if the plant received morning sunlight.
These plants can also tolerate more sun than other species in cooler climates. The heat of the summer in warmer zones (zones 7+) will be too much coupled with full sun and they may struggle. You are best sticking with a panicle for this region, as these varieties love the sun. You may notice the leaves wilting and drying out rapidly if they are receiving to much warm sunlight.
It will take about one year for your hydrangea to become fully established in your garden. Once its been established in the ideal location in your garden, watering will be moderate. During that one year time, however, you will need to heavily water. Depending on the rainfall amount in your area, you may need to water a few times a week to ensure that the soil stays moist.
When watering your hydrangea by hand, aim for the base of the plant and the soil surrounding it. They are very susceptible to fungal diseases, and water that is left sitting on the leaves will make these diseases more likely to appear on your plant, so try to avoid overhead watering. If you are using an irrigation system, drip irrigation is the best option, as it will keep the flowers and leaves dry, but well watered.
Remember to keep an eye on the weather- if it’s going to be especially hot you may need to water a bit more frequently. Don’t forget to use the leaves as your helper. I they have begun to droop or appear dry, then they will need some water!
While this species does require a good amount of water, they do not like having wet feet. The best way to prevent this, while also making sure your plant is getting enough water is to make sure that the soil you have is well-draining.
Adding organic material such as compost, peat, or even dried leaves can help with this. Mulching around the plant will help keep the soil cool while also keeping it moist.
This species is hardy in USDA zones 5-9. Plants grown in zone 5 should be protected over the winter by using burlap. In the warmer climates it is more essential that they receive afternoon shade.
Fertilizing can be as easy as adding manure or compost around the base of the plant upon planting and again in the spring or fall. Not only does this produce excellent results, but it will improve the conditions of your soil over time.
Another option is using a basic 10-10-10 fertilizer, or your choice of fertilizer labeled for flowering shrubs. Be sure to wrap up your fertilizing before August. This is when the plants are already preparing to go dormant and extra fertilizer could cause the plant to produce new growth that would not survive the winter.
During the summer months, they need very little maintenance aside from watering. I tend to do the bulk of my work in the fall.
Once a frost hits, the leaves will begin to turn yellow and fall to the ground. Remove these leaves by hand, or by using a small rake. This will help clear any leaf litter that could be diseased. It will give your plant lots of air circulation which will help keep your oakleaf hydrangea safe from any diseases.
If you live in zone 5 it may be important to protect them over winter. If you do choose to protect them, this can be done by gently wrapping your plants with burlap. Take your time with wrapping, as you don’t want the burlap to rub off any of the flower or leaf buds.
Hydrangea quercifolia blooms on what is called “old wood”. This is important to keep in mind when you are planning your pruning. Old wood is growth from the previous season. Plants that bloom on old wood set their leaf and flower buds in the fall.
This species is low maintenance and does not typically require a lot of pruning. They are at their best when they are left to grow freely, and pruned only for containment and to remove winter-kill.
They can be left until April before they are pruned. When you prune it should be done minimally. Deadheading can be done just after the blooms fade. Do this by snipping just below the flower and just above the next set of large leaves.
We know there are many species of hydrangea, but there are actually many varieties specifically in the oakleaf species. Let’s take a look at some of the most popular that you’ll likely come across when selecting a variety for your garden.
This is a very large variety up to twelve feet high and wide. The flowers are very long as well, reaching 12-14 inches. The creamy white sepals are very large as well, reaching to almost one and a half inches. All of these larger than life qualities make for one stunning plant. As the flowers age they slowly turn pink.
When summer turns to fall the deep green leaves take on a shade of burgundy. These colors make a really pretty autumn color combination. The size of ‘Alice’ makes it a good choice for a stand alone specimen plant, or perhaps planted as a hedge to offer some privacy.
The Pee Wee’ oakleaf variety is a compact variety for tighter spaces. This shrub will likely only reach three feet in height and width, which is quite a bit smaller than the rest of the oakleaf species.
The flower panicles reach four or five inches long and are creamy white in the summer and slowly fade to pink in the fall. The leaves will slowly change to a reddish purple when the temperatures begin to drop as well. These compact hydrangeas would make really nice foundation plants, container plants, or smaller hedges.
A mid-size shrub, ‘Ruby Slippers’ will grow to about three feet high and five feet wide. This plant is covered in showy white flowers that turn to pink a little earlier than the rest. Its leaves are a deep green until autumn when they turn a rich brown.
These plants make a great hedge, a backdrop for a foundation planting, or larger plant for a woodland garden.
This variety has really interesting flowers, made up of clusters of white flowers that will remind you of a snowflake, even on the hottest summer day. ‘Snowflake’ has a little more of a wild growth habit than some of the other species we typically see.
This growth habit makes it a fun choice for a woodland edge mixed in with other native perennials. Growing from four to six feet tall you could also use this as a border or a hedge to hide a fence or maybe an air conditioner unit in your yard.
A huge benefit to growing oakleaf hydrangeas in your garden is that the species itself is nearly trouble-free from pests and diseases however, deer can cause some trouble with this species.
Unlike other hydrangeas, oakleaf is a big favorite among deer. They will completely defoliate a shrub. Aphids and spider mites may arise on occasion, but this species shouldn’t typically become infested.
This species is susceptible to leaf spot which can be caused by a number of different fungi. Leaf spot could present itself as light brown spots with a darker brown border. Powdery mildew can occur but is not threatening. Both of these diseases can be prevented by minimizing moisture on the leaves.
Hydrangea quercifolia comes in a variety of sizes making its uses in your garden quite endless.
Choose larger varieties as stand alone plants, or grown together as a hedge. Medium size varieties will make excellent foundation plants, as well as smaller hedges around patios. This species can also be used in containers.
Their blooms make excellent additions to your flower arrangements. Snip the blossoms at any point in the season to enjoy them inside, or wait until they have begun to dry out and collect the blossoms you have deadheaded and add them to a dried arrangement.
Frequently Asked Questions
What should I plant with oakleaf hydrangea?
Incorporating this species into your garden can be a really fun task. These plants are native to the riversides of the southern United States. Their slightly wild growth habit makes them a great choice for a native garden. If this interests you, you could plant summersweet, sweetfern, or inkberry.
They are safe to plant with any perennials that like similar growing conditions. Their large leaves would do well to be accented by more delicate plants such as ferns, lilyturf, or evergreens such as boxwood.
Can I change the bloom color of my oakleaf?
The flowers of oakleaf hydrangeas are beautiful in their own right. For most of the flowering season these blossoms will be a creamy white panicle of flowers. As the flowers age they will turn shades of pink.
The flowers of other species are sensitive to the pH of the soil in your garden. Because of this, the color of the flowers can be manipulated by adding aluminum for blue flowers, or lime for pink. Unfortunately this species is not sensitive to the pH of the soil and will remain their natural color of white.
Will they rebloom in one season?
Oakleaf hydrangeas will only bloom once a season. They only form their flower buds on old wood, which is growth that has grown in previous seasons. However, they are considered long bloomers. Their flowers will arrive at some point in June and will last until the fall, fading into pretty pinks and reds.
They also have the added bonus of beautiful fall foliage color. The leaves will spend most of the season in a dark green, but once the temperatures begin to drop they will begin to change to shades of deep red, purple, or mahogany.
Are they fast growing?
Oakleaf hydrangeas are available in various sizes from compact to large. The larger varieties can reach up to 12 feet tall and wide. These shrubs are relatively slow growing shrubs growing about one to two feet per year. It is important when you are planting them that you leave enough room for it to grow to its full size. While this may take some time, it will be beneficial for the health of your plant.
Hydrangeas are such a vast genus of plants. There is a perfect species and variety for every garden. The oakleaf hydrangea is a special plant due to its interesting leaf shape, and beautiful large flowers. They tend to be more vigorous in the United States where they are native.
I would highly recommend adding this species to your native gardens or a woodland garden. Whether you are a novice gardener or a seasoned expert, adding oakleaf hydrangeas to your gardens will add great interest with little effort. If you’ve never given this plant a try before, I encourage you to look around your garden center for one on your text trip. Enjoy!