Knowing the final size of a plant is a very important part of garden design and plant positioning, and if you’re thinking of adding hydrangeas to your outdoor space, you might be wondering “how big do hydrangeas get?” These plants are beautiful, but they can get large, so you need enough space for them to thrive.
Hydrangeas come in a variety of sizes, depending on the kind that they are. Climbing hydrangeas can get to six hundred inches tall and about seventy inches wide, while Mountain hydrangeas (one of the smallest) tend to only be around fifty by fifty inches. You can also buy dwarf varieties that only grow to a few feet tall and wide. That means you can find a hydrangea to fit anywhere.
How Big Do Different Varieties Get?
Let’s explore the different sizes that the various hydrangeas can get to. Remember, the eventual size of your plant will depend on several factors, including the health of the individual plant and the environment in which it grows.
- Bigleaf hydrangeas: These grow to around ten feet tall and ten feet wide.
- Climbing hydrangeas: These can get over fifty feet tall and six feet wide.
- Smooth hydrangeas: These grow to about five feet in either direction.
- Oakleaf hydrangeas: These get to about eight feet in either direction.
- Panicle hydrangeas: Some specimens reach as much as twenty-five feet, although most will be more like fifteen feet.
- Mountain hydrangeas: These usually get to around four feet by four feet.
Most hydrangeas have about as much width as height, as you may have noticed. That means you need to leave a good amount of space around your hydrangea and make sure other plants don’t crowd it out as it gets large.
If you choose a dwarf hydrangea, you will need less space, often only around three feet in each direction. Make sure you read the estimates that the grower provides so you know how much space to leave.
How Fast Do Hydrangeas Grow?
There’s no way to determine exactly how fast your hydrangea will grow, as this will depend on many different factors, including the type of plant, how healthy the plant is, how often it is watered, how rich the soil is, how much light it gets, how crowded it is, etc. You can give it a boost by providing the best possible conditions, but the growth rate will still vary.
However, hydrangeas are classified as fast-growing plants, so you can expect them to fill a space reasonably quickly, which makes them great to add in spots where you need a burst of color and shape.
You can expect many hydrangeas to grow around two feet every year until they reach their maximum size. Hydrangeas are popular because of this quick growth, as it makes them useful for filling bare patches, but you may find you need to prune your plant to keep it under control!
How Often Should You Prune Hydrangeas?
You may sometimes find it is necessary to prune your hydrangea, but this needs to be done with care. Some varieties of hydrangea only bloom on their old, established wood, so if you cut this off, you’ll find that the hydrangea does not flower the following year; it needs to wait until it has old wood to produce its blooms.
This is not true for all hydrangeas, so it’s important to know what kind of hydrangea you have planted. Hydrangeas that need old wood to flower include:
- Climbing hydrangeas
- Oakleaf hydrangeas
- Bigleaf hydrangeas
- Mountain hydrangeas
If you cut off the old wood from these plants at the wrong time, they won’t flower that year. However, you can still prune them. You just need to wait until the plant has flowered, and then it can be cut back. This gives the plant’s new wood to harden and become old wood before the next flowering season.
Hydrangeas that bloom on new wood include smooth hydrangeas and Panicle hydrangeas. These can be pruned in the fall or early spring. Cutting away old wood will give them more room to grow new wood on which they can flower.
How Can You Stop Hydrangeas From Getting Too Big?
Because these plants are quick growers and most get quite large, you might be frustrated by how your garden is disappearing into a sea of hydrangea growth. If that’s the case, you’re probably wondering how you can slow their growth down and prevent them from taking over too quickly.
The best way is to prune them regularly. Frequent pruning will encourage them to grow bushy, rather than leggy, which is often more attractive anyway. It will also keep them smaller and give other slower plants a chance to compete with them.
Prune old wood blooming plants after they finish flowering (but before they start to bud in the fall). Cut away about a third of the longest stems, taking them right back to the level of the ground.
Prune new wood blooming plants in fall or spring, taking out some of the stems to encourage denser growth and reduce the size of the overall bush.
You can also minimize the fertilizer you use, as this reduces a plant’s ability to grow quickly. If you feed your hydrangea a lot, it is likely to grow much faster than if you leave it to find nutrients itself.
How Can You Make Hydrangeas Grow Quickly?
Perhaps you’re having the opposite problem, and you want your hydrangeas to get big as quickly as possible. Fortunately, this is also possible, provided you’re prepared to put a bit of time and care into your plant, especially when it is young and getting established.
Good conditions are the key to helping your hydrangea grow large quickly, so let’s look at what hydrangea needs to be happy and healthy. First, we’ll cover positioning, and then care.
These plants enjoy well-draining soil, so think about where you put your hydrangea and the kind of soil that you are digging it into. If you have heavy soil in your garden, such as clay, consider digging some soil improver into the ground first, before you plant your hydrangea.
You could also plant your hydrangea in a pot if you are concerned about drainage. This will let you control the environment around your hydrangea’s roots. Alternatively, add lots of compost, as this both promotes drainage and holds moisture well.
Think About The Light
Before planting your hydrangea, you should also think about how much light it needs. Check its preferences, as these will vary depending on the variety.
Some hydrangeas like full sun and others prefer partial shade, so look at the position you want it in and determine whether it will have enough light to grow happily there. If not, don’t put it in; the wrong light levels will result in poor growth or even a dead plant.
You may be able to find somewhere else to plant it, or you might be able to trim back other plants so that it gets enough light to grow properly.
Make sure that your hydrangea has enough room to grow into, or it doesn’t matter how fast it grows! You need to give it sufficient space, cutting back other plants if they are imposing on the space that you want your hydrangea to occupy.
Having space to spread out may help to encourage quick growth, and will mean reduced root competition and more nutrients available to your plant.
That covers most of the planting requirements, so what about care?
Plenty Of Water
Hydrangeas like to have a lot to drink. Although they prefer well-draining soil, they still enjoy regular watering, and if you want your hydrangea to grow quickly, you should make sure it doesn’t dry out too much, especially in the summer.
A thirsty hydrangea will not grow quickly and may even start to die back, so check on your hydrangea frequently and give it plenty to drink, especially when the plant is young and doesn’t have a very established root network with which to draw up moisture.
Giving your plant a good food boost a couple of times a year will help it to grow quickly. Your plant can’t grow if it doesn’t have sufficient nutrients to support new leaves and stems, so set a feeding schedule and stick to it to help your plant get big quickly.
Deadhead And Prune
Deadheading and pruning your hydrangea gently will encourage new growth (although hard pruning may keep the plant smaller). Removing flowers that have finished will prompt the plant to grow more, giving you a longer flowering season and a bigger, more beautiful plant to enjoy.
Hydrangeas can get large, and even the smallest ones are usually several feet tall. The very biggest varieties can get over fifty feet tall, and some spread to around ten feet wide. You need to make sure you leave sufficient space for your plant when you put it in and give it the best possible conditions to promote swift growth.