Botanical Name: Ageratum houstonianum ‘Aloha Blue’ 

Common Name: Floss Flower 

Hardiness Zone: Grown as an Annual in Most Climates (USDA Zones 2–11) 

Size: 10–14" Tall × 12–16" Wide 

Growth Habit: Compact, Mounded, Well-Branched Habit 

Sunlight: Full Sun to Partial Sun 

Soil: Well-Drained, Moderately Fertile Soil 

Water Needs: Moderate; Even Moisture for Best Performance

Bloom Season: Late Spring Through Frost 

Fertilizer: Light, Regular Feeding During the Growing Season

Features: Soft Blue Blooms, Dense Flowering, Excellent Uniformity, Pollinator Friendly 

Uses: Ideal for Borders, Edging, Containers, Window Boxes, and Mass Plantings 

Patent: ✔ Patented 

Propagation: ❌ Propagation Prohibited Without License

See our complete Ageratum Plant Guide for full care details.

More About Ageratum Aloha Blue

Aloha Blue is an Ageratum that might not grab your attention from far away, but the longer you work with it, the more you realize how valuable it really is. I first started using it when I needed a true blue that wouldn’t get tall, floppy, or unruly by mid Summer. Older Ageratums had burned me before—great early on, then suddenly stretched out, leaned over, or smothered everything around them. Aloha Blue never did that. It stayed exactly where I put it, growing into a tidy, well-balanced mound that looked intentional from planting day all the way into fall.

When everything else is pushing hard—big leaves, bold blooms, high contrast—Aloha Blue gives your eye a place to rest. The color itself deserves some attention. This isn’t a harsh or electric blue, and it doesn’t drift purple or gray as the season wears on. It stays soft and consistent, even in full sun, which makes it surprisingly easy to design with. Bloom-wise, it’s steady rather than showy. It doesn’t come on all at once and then fade; it just keeps flowering from late spring through frost, filling in as it goes. That kind of consistency matters more than most people realize, especially in landscapes that need to look good for months, not just a few weeks.

Why We Like It (Our Trials)

We tested Aloha Blue thoroughly in the Upstate of South Carolina, and it proved itself well enough to be one of our go to varieties. Through heat, humidity, and those long spells where everything else either stretches or sulks, Aloha Blue stayed dense and flowered evenly. It didn’t need constant attention to keep its shape, which tells me the genetics are doing the work instead of relying on garden maintenance to hide any flaws.

We ran it with regular watering and light feeding, nothing fancy, and it held together beautifully. No aggressive trimming, no midseason rescue efforts. That matters in real gardens, where time is limited and plants need to carry their weight without babysitting. What I personally appreciate most is how easy it is to place. It plays well with brighter annuals without competing, softens hard edges along beds and paths, and anchors containers without stealing the show. It’s not a plant that demands attention—but it’s one you miss when it’s not there. Over the years, I’ve learned that those are often the best plants of all.

Aloha Blue vs. Other Ageratums

Aloha Blue brings a softer, cooler presence to the garden, offering calm contrast and visual relief when paired with bolder colors, while Aloha White reads brighter and sharper, especially in sun, where it pops cleanly against foliage. I tend to use Blue when I want things to feel settled and cohesive, and White when I need definition, lift, or a little extra light in tighter spaces.

Compared to taller selections like Blue Horizon or pollinator-focused varieties such as Monarch Magic™, Aloha Blue remains noticeably shorter and more controlled. While those varieties excel in mid-border roles with height and large flower heads, Aloha Blue is best suited for precision planting where neat form and uniformity matter most.