How to Grow & Shape Your Hydrangea Shrubs into Trees
If you are trying to grow your hydrangeas into a tree, but don't know where to start, you are in the right place. Growing hydrangeas as trees can be a little bit of a challenge, but it can be done with a patience and dedication. In this article, gardening expert and hydrangea enthusiast Jill Drago walks through each step you'll need to follow for beautiful tree like hydrangeas.
Hydrangeas are quite possibly one of the world’s most versatile shrubs. There are species that tolerate shade, as well as species that tolerate full sun. The generous flowers come in dreamy shades of white, pink, purple, blue and red. There are climbing vines, shrub varieties of varying sizes, and yes, tree-like forms.
There are many tree formed plants available at your garden center from roses to lantana. This plant form, also known as standard form, is an elegant form of plant. Tree-form hydrangeas are available at your garden center, and they come at a high cost. While this cost is justified when you consider how much patience and care goes into perfecting these plants, you can easily save some money and take this task on yourself.
Pruning your panicle hydrangea into a tree is a process that you can do at home on your own with just a small amount of guidance. All you will need is a hydrangea, your pruning tools, and a bit of patience.
Step 1: Pick Your Plant
The best species for this pruning project is Hydrangea paniculata, or more commonly: the panicle hydrangea. Panicles are also known as tree hydrangeas, due to its ability to take on a tree-like form via pruning.
Panicles love the sun and are very tolerant of full sun locations in your garden. They are also some of the hardiest in the bunch, ranging from USDA zones 3-8. Most of these plants are very large, growing to eight feet. Their flowers are white or green at the start of blooming and will mature into varying shades of pink.
When you are choosing your plant keep in mind what the mature size of the plant will be. While many panicles are large, there are also some dwarf varieties. Tree form dwarf varieties would be greatly used in containers, but they might not meet your expectations in your garden.
Starting With Cuttings
Beginning with a rooted cutting is arguably the more effective way to do this type of pruning. You will have much more control, but you will also have to wait a bit longer to have a fully grown plant.
To take a cutting, look for a green stem on your plant that is about six inches in length that have not flowered yet this year. You will want to make sure there are at least a few sets of leaves on this branch.
Take a cutting from an existing panicle hydrangea in May or June and remove all but two sets of leaves. Dip the cutting in some rooting hormone, and plug the cutting into some sterile growing medium. Once this cutting has taken roots you can begin to train it into a tree form.
If you are choosing to start from a cutting, the pruning process will essentially be the same. It will be a bit more delicate and time consuming however since you will be starting with a much younger plant than if you were starting with a potted nursery plant or a hydrangea already established in your garden.
Pruning Established Plants
If cuttings aren’t your thing don’t worry. You can also train your panicle hydrangea to grow into a tree form even if you have just purchased a potted plant from a garden center, or an established plant in your garden.
Whether in a pot or in your garden, you will want to start with a healthy plant with lots of growth. You will also want to begin pruning before the branches are too thick. This will help to ensure that the wounds from pruning will heal nicely and will not put too much stress on the plant.
We want the plant to put energy into a branching, and not too much on healing. Lots of new growth will also signal that you have a vigorous grower and will be able to produce lots of new growth once you start pruning.
Step 2: Clean Your Tools
Before you begin any pruning, but especially something as detailed as this you will want to start with clean tools.
Give your pruning shears, or garden clips a quick wipe down before you get to work. This will help to remove any debris that may be lingering from the last time you used them. Clean and disinfect your pruning shears with diluted bleach or rubbing alchohol and allow them to dry before you start pruning.
Step 3: Begin Pruning
When you start to trim back your plant, the process will differ depending on what type of plant you start off with. Let’s take a look at each important step to follow when beginning to prune back your shrub to take the shape of a tree. Before we look at each step, there’s a few important tips to remember:
- This pruning and growing process can take up to two years (or more) to take hold.
- Panicles bloom on new wood.
- The timing of pruning may mean you will lose your flowers for a season.
- Focus on the foliage during this process, the flowers will come back.
Starting With Hardwood Cuttings
- Wait for your cutting to take root.
- Remove all of the leaves from the cutting except for a few at the top.
- By doing this you will be removing the apical meristem of the plant.
- This will encourage outward branching.
- Move on to step 2 in “starting with a nursery plant.”
Starting With a Nursery Plant
- Select a stem that is strong, and straight.
- This will become the main leader of your tree.
- Prune away competing stems, or stems that will take away from your desired shape.
- Prune away any shoots that are coming from the ground, or from lower on the stem.
- You will want to make these cuts as close to the ground as you can.
- Use a stake to support your plant as they may become top heavy.
- Too much wind or rain on a top heavy plant could end up damaging the leader.
- You may opt to use garden velcro to support plants.
- Place the stake close to the stem, and deep enough to support the plant.
- Six inches should do the trick. Be careful, and do your best to avoid damaging the roots.
- Frequently remove any new shoots that are forming on the new trunk of the plant.
- Wait for new growth to appear in the following spring.
- Remove any branches that may have formed on the bottom half of the leader.
- Again in the spring, give the tip of the main leader a small haircut just below a leaf node.
- This will again encourage more outward branching, and limit the upward growth.
- Most panicle hydrangeas can be pruned in the early winter, or the spring.
- Do your pruning in the early winter to protect the shape of the tree from winter damage.
- The weight of snow could easily crack these tender branches if they are too big.
Step 4: Planting Your Hydrangea Tree
All of your hard work training your hydrangea into a tree should be shown off. They make a perfect focal point of any garden. The space between the ground and the lowest set of branches is the perfect place for some low growing perennials.
Tree form panicles make a very formal hedge that can have another row of perennials in front of them, creating a secret garden type of feel. They can also be used as the “thriller” in large containers.
Do not be intimidated by these steps. Anyone can do this. As with most care recommendations for hydrangeas, they only seem complicated. Once you get started you will notice that they are simple steps. You will become best friends with your plant and your pruning shears, and it can be very therapeutic. Take your time, pour a glass of iced tea and enjoy snipping and shaping your beautiful new hydrangea tree. The effort will be worth it!