How to Combine Alliums with Perennials
Garden designers love using alliums and it’s easy to see why. These flower globes grab your eyes with their bold shapes and sparkly florets. They bloom for weeks in late spring and early summer, and the seed heads add interest for months, long after the flowers are gone. Alliums are reliably perennial and they are not troubled by deer or rodents. Pollinators love them, too.
Observing how garden designers combine alliums with perennials can be a great source of inspiration for your own garden. Read on to see some examples of creative and unexpected pairing. (Note: this article features alliums that are grown from bulbs rather than herbaceous alliums such as Allium ‘Millenium’ and Allium tuberosum.)
Combining Alliums with Other Perennials
Don’t make your alliums go it alone. Without other plants beneath them, the long stems tend to look gangly. Like other spring bulbs, alliums lose their foliage shortly after they bloom. If there are no other plants to fill in the gaps, you will left with… gaps!
And here’s another good reason to have your alliums emerge from a bed of foliage. With some types, including Purple Sensation and most of the big-headed varieties, the leaves begin to yellow while the flowers are still in bloom. The best way to hide those leaves is beneath the foliage of other perennials.
Below is a list of perennials that work well with alliums. Later in the season many of them would be too tall, but the scale works because they’re still young when the alliums are in bloom.
- Ornamental grasses
- Lady’s Mantle
- Nepeta (catmint)
Plan for Contrasting Heights
Some alliums rise to a height of 4 feet, while others never get taller than 6 inches. This is why it’s important to stop and think about which type of allium you’re planting and where it’s going.
Short ones like karataviense (6”), ‘Graceful’ (10”) and schubertii (15”) can be planted near the front of a flower bed where they’re easy to admire. Locate mid-size types in the middle and the tallest ones at the back. You can also ignore all that and use tall alliums as “see through” plants — example below.
Get Creative and Experiment with Color and Form
I saw the combination shown above at Trentham Gardens in Staffordshire, England. Waves of ornamental grass (Nassella tenuissima) were paired with big-headed alliums, possibly Gladiator. It was bold and surprising in the best sort of way and accentuated the distinctive forms of these two very different plants. Can you imagine a place in your garden where something like this might work?
Let the Seed Heads Linger
When alliums have finished blooming, don’t be too quick to remove the spent flowers. The show continues! Most types develop decorative seed heads that will persist for weeks — and some for months. This year it was early September before I finally pulled out the allium christophii and brought the seed heads indoors to enjoy around the house.
In the garden, allium seed heads look best when they’re in a relatively open area that’s not too crowded with other plants. This makes it easier to appreciate their unique shape. Plus, good air circulation helps them stay dry and so they are less likely to fall apart.
Planning for Different Bloom Times
Our Bloom Time Chart for Alliums shows when each type of allium blooms. When you’re combining alliums with perennials, this makes it easy to plan for specific plant pairings and also pace the bloom time so you can can have alliums flowering from early May through late June or early July.
Note: If you’re considering planting allium schubertii (you should!), it’s not on the bloom time chart but you can expect it to bloom at approximately the same time as Globemaster.
Alliums are available for shipping/planting from September-November, click HERE to see our selection. To learn more about growing alliums, you may be interested in reading: All About Alliums, Types of Alliums and Alliums for Every Garden. Garden designer Nick McCullough has also designed two allium-focused planting plans that are available free HERE and HERE.