Should You Plant Hydrangeas Underneath Trees?

Hydrangeas: the lifesaver of the shaded garden. Their colorful blossoms bob along all summer long keeping all of us shade gardeners quite happy. Native to both Asia as well as the United States, these popular shrubs have become irresistible to homeowners for so many reasons. This often leads to gardeners with less space to plant, looking for places to plant them, like under a tree.

But should you plant hydrangeas underneath trees? Will they truly thrive there, or are there better places to put them?

Almost every gardener understands the appeal of planting these beautiful, bright blooming shrubs in their garden. They are low-maintenance plants and grow easily in many different climates making them a great garden choice for gardeners almost everywhere. Let’s take a deeper look to discuss if planting your hydrangeas underneath a tree will allow them to thrive, or cause them to falter.

Now, The Long Answer

Hydrangeas love partial shade. They love the deep, or dappled shade that trees offer them, and the breaks from the sun they provide. So it just seems natural to plant them under a tree right?

Wrong.

Despite the recommendation by some gardeners, we’d advise against planting hydrangeas under any trees if you want them to reach their fullest potential. The reason for this is simple: too much competition.

While it’s “possible” to plant them under a tree successfully, many hydrangeas planted under trees will not thrive as well as if planted elsewhere in your garden. There are other plants better suited for life underneath a tree than hydrangeas.

It is likely that the roots of the trees would outcompete the hydrangeas for water as well as nutrients. The end result would be a sad one. While they may survive but they would absolutely fail to thrive.

This is also because the canopy of the tree would block any rainfall that the hydrangea would benefit from, which would cause the competition to become even more fierce.

While they love the shade, they also need some sunlight. Morning sun is preferred because it is not quite as hot and the plants will have the day to recover.

If your hydrangeas don’t get enough sunlight it is likely that the plant will not flower at all, and if it does the flowers will be very small. You could also risk the stems becoming leggy as they reach for any bit of sunlight. Leggy hydrangeas not only look unattractive, but they will lack the strength required to hold up any blossoms that may form.

Where Should I Plant Them?

To be safe, it is best to plant your hydrangeas out of reach of the tree’s main roots. Hydrangeas (with the exception of Hydrangea paniculata which prefers full sun) do best in partial shade with morning sun for about four to six hours.

They also love well-draining soil, and a moderate amount of watering once they are established. Newer plantings will need more frequent watering.

Perennial Gardens

Hydrangeas will fit into any type of garden you have as long as the growing conditions are correct. Use them in a foundation garden, a perennial garden, or a cutting garden.

Smaller plants, and especially the compact or dwarf varieties make really nice additions to a perennial garden. I find them to be unexpected when planted in this way.  They also make a nice hedge growing along the front of a home. You can’t get much more classic than that.

Borders

If you have a lot of trees in your yard with border gardens along their woodland edge, this would be a great place for a mass planting of hydrangeas. Mass plantings can make a really elegant sight to curved edges of your yard.

Larger species and varieties also make really nice borders. If you choose a new wood bloomer such as smooth hydrangea or panicle hydrangea just keep in mind that the border will not provide any privacy for you in the months after you have pruned them.

I typically like these species best as a border because they have a more wild growth habit and are more whimsical than they are formal and upright.

Containers

Filling containers with hydrangeas and placing them under a tree is a great option! In fact, I love a well placed container on an old tree stump that lingers among other trees. It adds the perfect type of plant to a place where nothing much else would survive.

When you are planting hydrangeas in containers you will want to make sure you have a very large pot, as they need plenty of room to grow! They will also need more frequent watering than any that are planted in your garden. Place these containers anywhere on your property that has the right conditions for them, including underneath the canopy of a tree.

What about raised beds?

You may see advice about building a raised bed underneath your trees to accommodate larger plants. While this might provide the hydrangea with ample room to grow it would be detrimental to your tree.

Trees have small surface feeder roots that are typically responsible for providing some oxygen to the tree, as well as water and nutrients. If you build a raised bed on top of these roots you will be preventing them from doing their job.

This may not immediately kill your tree, but you may notice that it becomes more susceptible to diseases and is a bit more stressed overall. Over time this could lead to the death of your tree and cause problems for your hydrangea.

The Exception to the Rule

While the above still remains true, there is one hydrangea that will grow well under a tree. It is even often recommended that you do so. This hydrangea is: Hydrangea anomala also known as the climbing hydrangea.

The climbing hydrangea does best when it is climbing up a rough surface such as a fence or a tree trunk. They climb and spread using aerial roots to hold on to their climbing surface.

Their flowers are white and can grow up to eight inches across. These flowers are delicate, and resemble a lacecap. They bloom in the late spring into the summer. Once the flowers have passed and you have removed the spent blossoms,  you will be left with attractive heart shaped leaves.

Here are some popular climbing varieties:

Hydrangea anomala ssp. Petiolaris

This is the most popular species of climbing hydrangea. This is a dependable grower with shiny green leaves and airy white flowers. It’s quite common to find this hydrangea variety in a myriad of different locations, including climbing on trees.

Hydrangea anomala ‘Silver Lining’

This is a newer variety of climbing hydrangea. ‘Silver Lining’ has pretty variegated leaves with a nice white edge to them. The flowers are white and lacy when they bloom.

Image Credit: Leonora (Ellie) Enking via Flickr (Image Usage Allowed With Attribution)

Hydrangea anomala ‘Flying Saucer’

This variety is aptly named for its gigantic flower, much larger than the other climbing hydrangea varieties. It looks a bit like the more common petiolaris, but with larger white blooms.

What Should I Plant Under My Trees?

If you have empty beds under a grouping of trees and you are wanting to plant something in the beds there are still options. You will want to choose plants that are smaller, and have less aggressive root systems than a larger shrub. Here are a few options:

• Annuals
• Ferns
• Hellebore
• Hosta
• Pachysandra
• Spring Bulbs

When you are planting these plants under trees, be gentle with your digging. Try to find spaces in between the roots so as to not disturb them too much. Don’t overcrowd the plants either. Everyone will need time to acclimate to their new environment. Watering these new plants will be important so that the competition will be less aggressive.