When it comes to combining beautiful, interesting flowers and easy care in one plant, easy-to-grow alliums are the real deal. You're probably familiar with the classic allium look and color: Big purple globes on tall stems. But you’ll also find flowers in other shades of purple, pink, white and yellow. Flower shapes can be larger, looser or even drooping, and they can vary in bloom time, too. Here's everything you need to know to about how to grow alliums.
The only drawback to this plant? By the time most allium flowers are looking great, leaves have started browning. Just position them close to other plants that can hide spent foliage.
How to grow allium
Ornamental onions thrive in full sun and well-drained soil. Early alliums need moisture while growing, then dry soil the rest of the year. Later bloomers do well in a typical well-drained garden site. You can buy alliums as plants or bulbs. The onion family includes all sorts of ornamental bulbs for almost every garden situation. Plants are available spring to early summer, and that’s the time to plant and transplant them.
Plant allium bulbs in fall
The time to allium plant bulbs is fall and a stand-up bulb planter can make fast work at planting time. Here are some tips to get you started:
- Space allium bulbs at two to four times the bulb’s width and set them two to three times as deep as its diameter.
- For large alliums that’s about 8 to 10 inches apart and 6 inches deep.
- Smaller allium should be 3 to 4 inches apart and about 4 inches deep.
- After the soil freezes, mulch the new bulbs.
- Fertilize alliums in fall when roots begin to grow. Use an all-purpose bulb slow-release fertilizer that supplies nutrients throughout the growng season.
Different types of allium
There are alliums for about any spot in your garden. Take a look at some of our favorites below!
‘Pinball Wizard’ allium (Allium hybrid)
This standout cultivar has densely packed flowers, which are easy to see from a distance. Groups of three to five bulbs planted together really pop. ‘Pinball Wizard’ is a slightly smaller version of ‘Globemaster’, which grows a little taller — up to 36 in. If you’d like a similar look with white flowers, try ‘Mount Everest’ (A. stipitatum); it has 4- to 6-in. flowers on 24- to 36-in.-tall stems.
Type Bulb Blooms 6- to 8-in. lavender flowers in late spring Light Full sun Soil Well-drained Size 18 to 24 in. tall, 5 to 8 in. wide Hardiness Cold hardy in USDA zones 5 to 8
This low-growing cultivar has a flower that looks like exploding fireworks! Stick with a simple color palette and the flowers will be more visible. The pink dianthus (Dianthus hybrids) and silver dusty miller (Senecio cineraria) here don’t need additional watering (which causes allium bulbs to rot) and will have filled in by the time allium foliage disappears in summer.
Type Bulb Blooms Loose 12- to 18-in. rose-colored globes in late spring Light Full sun Soil Well-drained Size 12 to 24 in. tall, 12 to 18 in. wide Hardiness Cold hardy in USDA zones 4 to 9
Drumstick allium (Allium sphaerocephalon)
You can get about 10 of these small bulbs per square foot, and where they’re happy, they may naturalize. If you don’t want them to reseed, remove the egg-shaped spent flowers from their long, sturdy stems after they fade. Another well-mannered and small-flowered allium you might like is Allium caeruleum. It’s a little shorter with round sky-blue flowers in early summer.
Type Bulb Blooms Deep burgundy 1- to 2-in. flowers in early summer Light Full sun Soil Well-drained Size 24 to 36 in. tall, 3 to 6 in. wide Hardiness Cold hardy in USDA zones 4 to 9
‘Summer Beauty’ allium (Allium lusitanicum)
While many allium bulbs produce a single flower, they don’t all grow that way. This cultivar, often sold as Allium tanguticum, is similar to chives and forms clumps: Multiple flower stems bloom in summer, and after they fade, the seedheads last well into winter. The flowers are sterile, so you don’t have to worry about it reseeding (like you do with chives).
Mounds of dark green foliage look good all season, making it an excellent choice for mass plantings and mixing into perennial borders. And since ‘Summer Beauty’ is drought-tolerant, you can grow it in out-of-the-way spots the hose doesn’t reach.
Type Bulb Blooms 1½- to 2-in. mauve-pink flowers in summer Light Full sun Soil Well-drained Size 18 to 20 in. tall, 8 to 12 in. wide Hardiness Cold hardy in USDA zones 4 to 9