9 Stunning Ornamental Grasses That Grow Beautifully With Hydrangeas

With their abundance of big kahuna blooms, hydrangeas are show-stopping plants that do a lot of heavy lifting for gardeners. They can grow to massive proportions in spots that can be challenging for other plants to thrive in and reward you with bountiful clusters of blossoms. Plus, they help unlock secrets about what's going on in your soil, thanks to their color-changing abilities based on the pH levels of the dirt they're planted in. But no person, or hydrangea, is an island; we all like to hang around like-minded folk — or flora, for that matter.

That's why we've rounded up a collection of ornamental grasses that play well with hydrangeas. Not only are these grasses easygoing but, like hydrangeas, their stunning appearance can turn sparse borders into a beautiful landscape design. Besides being an elegant addition to your garden overall, ornamental grasses, with their bladed structure, can create an eye-catching contrast against the rounded, voluptuous silhouettes of hydrangeas. The best ornamental grasses to grow next to hydrangeas are ones that enjoy similar growing conditions and are easy to manage. We'll walk you through why the following grasses make such great hydrangea BFFs and break down a few care requirements you should know in order to plan your garden design like a pro. So grab your trowels, and let's (pardon the pun) dig in. 

First, let's ensure we're all on the same page regarding how to grow and take care of hydrangeas so that you have a quick reference. Luckily, hydrangeas are pretty easygoing plants that can take care of themselves without too much fuss, provided you give them the right location and consistent moisture. One thing to consider, though, is their size. Obviously, we're all rooting for your hydrangea to become a massive display of purple, pink, and blue flowers, but hydrangeas can only grow as big as their space allows, so make sure you've got enough room. A good plot size for a single hydrangea bush depends on the cultivar you're planting: Smooth (Hydrangea arborescens) and bigleaf (Hydrangea macrophylla) varieties need a space that's 3-5 feet wide. Panicle hydrangeas (Hydrangea paniculata) is the big mamajama variety that can reach anywhere from 10 to 20 feet across so be careful picking this one if you've got a small garden. 

Oakleaf hydrangeas (Hydrangea quercifolia), commonly found in the Southern U.S., are a little more difficult to generalize since different varieties have different growth patterns. Varieties like 'Snow Queen' can reach up to 8 feet across, while 'Pee Wee' stays compact at a max of 3 feet, and 'Alice' literally overshadows all, topping out at 10-12 feet tall. 

The best spot to plant hydrangeas is in partially shady areas that receive morning sun and have well-draining soil that's loamy and rich with organic matter. The soil should remain consistently moist but never be so wet that it's waterlogged. They can handle a wide array of pH levels, and you can tweak pink blooms a smidge over to the bluer side by using acidifying fertilizers, like Jack's Classic 7-3-3 Hydrangea Blue Water-Soluble Fertilizer. 

Japanese forest grass (Hakonechloa macra) has growing conditions so similar to hydrangeas that we're surprised they're not twins. They, too, need shady spots and well-draining soil that's consistently moist. While forest grass does flower, its blooms are a yellow-green color and blend in with the foliage, leaving your hydrangea's blossoms to be the stars of the show.

Japanese forest grass prefers cooler temperatures to hotter climates, being happiest in USDA hardiness zones 4 through 7, however, some cultivars are less cold-hardy and are listed only to zone 6. Most varieties of Japanese forest grass are typically green — or have a variegated white stripe, sort of like spider plants — but you'll need to position yours in a spot that's shielded from the sun to make those greens pop. Cut it back to the ground before the spring growing season to give your specimen the best chance of pushing out lush blades. Japanese forest grass is a slow spreader that can take years to reach its maximum clump size (or be ready for division), so this isn't a plant you can quickly propagate to fill up a bed. You may want to buy more mature plants if your hydrangea is well-established to create visual balance, and so that the size difference doesn't give the hydrangea an upper hand over resources. Speaking of resources, you'll want to give this grass just as much compost and organic matter as your hydrangea, especially in heavy clay soils or ground that's apt to dry out quickly. 

If you're looking for a grass that can complement hydrangea flower colors, then feather reed grass (Calamagrostis x acutiflora) is for you. Feather reed grass stays fairly compact but can reach up to 5 feet tall when happy. Not only does it love rich, fertile soil and staying out of the sun, but its beautiful, pinkish-plum spikelets (whose florets fade to hay-colored seed heads) are a sight to behold next to magenta, blue, or even purple hydrangea flowers.

Unlike Japanese forest grass, feather reed grass is a fast grower and won't be outcompeted by mature hydrangeas for resources easily. And don't worry; despite being a rapid grower, feather reed grass seeds are sterile, so they can't self-seed and become invasive. Make sure the soil stays consistently moist and isn't able to dry out — you can even try watering with diluted Castille soap to help your reed grass get hydrated if the soil has become hydrophobic. Finally, cut the plant back down to the ground in winter so that it pops up with fresh, new growth in the spring. There are two varieties that you'll typically find for sale: 'Karl Foerster,' which is the earlier bloomer, and 'Overdam,' which has variegated blades. 

If you love spider plants, then Japanese sedge (Carex morrowii) is bound to be a favorite. Its striped leaves can look incredible next to hydrangeas, and the contrasting colors are ideal if you want to put a maximalist spin on your garden. Japanese sedge prefers the moist soil and shade conditions hydrangeas love, and will only get around 18 inches high, making it a perfect companion for the compact 'Pee Wee' cultivar. You can also use this ornamental grass to create an eye-catching strip of edging in front of tall hydrangeas in your borders. 

Japanese sedge is a dense grower, making it a perfect plant for filling in blank spots in your beds. While it's not necessary to "prune" these plants, if the blades start to look a little ragged, you can cut them back in late winter (just be careful not to cut stems lower than 2 inches) to enjoy a fresh set of foliage in the new growing season. While not considered invasive, Japanese sedge spreads via rhizomes, so keep an eye out for baby sedges popping up where you might not expect. This is definitely one of the more forgiving ornamental grasses since it's drought-tolerant, so if you tend to forget a watering here and there, opt for this grass.

Autumn moor grass (Sesleria autumnalis) comes from European moors and puts out a feathery inflorescence that can add interest at a time when all hydrangea displays are coming to an end. Plus, it's super versatile and goes with the flow, especially in the well-draining soil conditions that hydrangeas need. In some areas, autumn moor grass will even continue to bloom throughout the winter, making this not only a good friend for your hydrangea bush but also a great plant to chase the winter doldrums away.

Autumn moor grass typically only grows just over a foot tall, so you may want to give it a little bit of breathing room from bigger hydrangea varieties. Plant it somewhere that stays cool in the summer, as, like hydrangeas, this grass doesn't enjoy really hot conditions. If your hydrangea spot has a tree nearby, placing your autumn moor grass just under the canopy (but not too close to the trunk) should make it super happy by providing some shelter from heat. As you might've guessed from its name, autumn moor grass starts flowering in the fall, sending purple-tinged flower spikes straight up that eventually fade into a feathery silver. 

Seeing pictures of tufted hair grass (Deschampsia cespitosa) just makes us want to spend the day running our hands through its feathery foliage. This native grass was made for semi-shade and loves moist, well-draining soil that's full of organic matter, so it's more than happy to hang out in hydrangea's neck of the woods. Tufted hair grass typically grows up to 4 feet, making it a good neighbor for medium-sized hydrangea varieties. 

What's cool about the tufted hair grass is that its flowers are usually slightly multi-colored clusters, ranging from gold to pale purple, making this a dynamic-looking plant in more ways than one. To get the biggest burst of flowering out of your tufted hair grass, plant it in an area that gets a little more shade than sun, but isn't super shady. It can self-seed if it settles into a spot with ideal growing conditions but isn't considered invasive due to its native origins. However, you may want to keep an eye on it to make sure it stays in place and doesn't begin to wander.

Grassy-leaved sweet flag (Acorus gramineus) isn't technically a grass but has become a favorite asterisked ornamental "grass" for gardeners since it's so hardy. It loves moisture so much that it can actually live in standing water that's up to 4 inches deep, making it a potentially good plant friend to have if your hydrangea's plot teeters between perfectly moist and slightly waterlogged. While it can handle full sun, grassy-leaved sweet flag prefers cooler temperatures and should be able to handle hydrangea's preferred partial shade conditions with no problem.

Grassy-leaved sweet flag does flower, though the blooms look more like corn on the cob than a floral blossom, so they won't stand in the way of letting hydrangeas be the main attraction. And anything it lacks from a flowering perspective it makes up for in scent — the foliage is known for its sweet smell when crushed or bruised, making it great for sensory gardens. It will only get around a foot high and is a slow grower that's not deemed invasive, even though it spreads via rhizomes. If you're still nervous it might get out of hand, plunk it in a container or drop it in a spot that gets lots of water, like the bank of a shade dappled pond (which can also provide the consistent moisture hydrangeas need). Sweet flag may be hardy, but it's not hardheaded enough to rapidly wander away from the slightly aquatic conditions it loves into dryer territory. 

Want an almost guaranteed win? Plant some northern sea oats (Chasmanthium latifolium), sit back, and watch it grow. Northern sea oats are incredibly easy to care for, love the same partial shade and moist, well-draining soils that hydrangeas do, and are even award-winning. Northern sea oats was selected as 1994's NC Wildflower of the Year, making it as close to a "Miss America" ornamental grass as we'll ever get.

Northern sea oats are native to the eastern U.S. and northern Mexico, so they aren't considered invasive, but they can spread like wildfire if you're not careful about deadheading. Despite its name, there aren't any delicious grains to harvest; the "oats" refers to the resemblance of its seed heads to oats. Even though its prone to spread and is lacking in actual oats, there's lots to like about this grass. Its aforementioned seed heads flutter in the gentlest breeze and will turn from a pale green to bronzy copper, finally finishing with a pretty purple hue in the fall that matches nicely with the burnt orange foliage, making it full of sensory delights. Expect it to top out at around 2 feet high and plant it in the same consistently moist but well-draining soil you're giving your hydrangea. Northern sea oats can handle more sun than hydrangeas but is very shade-tolerant as far as grasses go. It's also a hub for butterfly larvae, making it a top choice for bringing pollinators to your garden. 

Want to have a patriotic-themed garden? Plant a smooth or oakleaf hydrangea bush, both native to Alabama, and some American beakgrain (Diarrhena americana or Diarrhena obovata). These shiny, green grasses love moist soils full of rich, organic materials and can hang out with hydrangeas in the shadiest of conditions. Their dense growth patterns are great for filling in the gaps between hydrangea bushes, and their easygoing attitude ensures you can focus on feeding and pruning your hydrangeas correctly, and let the beakgrain do its thing.

Despite being two separate species, there's not much difference between the two beakgrains. The major distinction is that Diarrhena americana hails from the eastern U.S., while obovata starts around Ohio and makes its way west. Both will spread to about 3 feet wide and are grown for their foliage more than their yellow-green flowering panicles. Their striking blades starts as a true green that changes with the seasons, eventually turning a lovely golden hue in the fall. They are one of the few grasses that can grow in full shade without issue but need rich soils that stay consistently moist, so consider adding in organic material via compost. If you're wondering how much compost you should add to garden soil, be generous, as most plants will do well in a medium that contains 20%-30% compost. Beakgrain spreads via rhizomes and can form dense colonies, which may be a pro or a con, depending on your landscaping plans. 

Not only is black mondo grass (Ophiopogon planiscapus) fun to say, but its dark leaves make it a contrasting companion for hydrangea's brightly colored blooms and lush foliage. Like hydrangeas, black mondo grass loves spots with moist, well-draining soil and partial shade. It even prefers its soil to be slightly acidic, and so should be able to handle acidifying hydrangea fertilizer without a problem. 

Black mondo grasses don't get very big, maxing out around a foot high, so they are probably best planted next to smaller hydrangea cultivars, or in front as a border. Their growth pattern is like a tufted clump of foliage that ranges from a matte charcoal to a perfect goth black, which makes their blush pink or cream-colored flowers and dark purple berries stand out all the more. Caring for your mondo grass is easy: Keep its soil slightly acidic and consistently moist, and make sure it's sheltered from the harsh afternoon sun. Mondo grasses spread via rhizomes but are slow-growing, so they shouldn't become a nuisance or get out of hand. However, some offshoots can revert to green and may need to be culled if you exclusively want the dark coloration.