Ageratum (Flossflower) in Zone 5a & 5b
Ageratum houstonianum
When to plant ageratum (flossflower) in zone 5b
Zones 5a and 5b share the same average frost dates in our data, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. Ageratum (Flossflower) needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Mar 22–Mar 29 |
|---|---|
| Direct sow / transplant outside | May 17–May 24 |
| Estimated bloom | Jul 31–Aug 7 (~75 days after transplanting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-2 ft.
Ageratum, also known as flossflower or blue mink, is a fuzzy-textured filler flower that's a classic choice for the back of a bed or a mass planting, needing no pinching or staking along the way.
How ageratum (flossflower) fits zone 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Ageratum (Flossflower) needs about 75 days from transplant to first harvest.
Good companions
No standout companions recorded yet for Ageratum (Flossflower).
Where to buy ageratum seeds
See why we recommend these suppliers →
As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a genuine consensus of positive, independent reviews. See the sources cited on each item.
See it growing
Search YouTube for "growing ageratum (flossflower)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 5b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
%20in%20USDA%20zone%205b%3A%20when%20to%20start%20seeds%20indoors%2C%20when%20to%20direct-sow%2C%20and%20when%20to%20expect%20a%20bloom.)
Pin this for later
Growing Ageratum (Flossflower) in USDA zone 5b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
Save to Pinterest