Photo: C T Johansson / CC BY 3.0 / Wikimedia Commons

Ageratum

Ageratum houstonianum

Also called Floss flower, Flossflower, Bluemink and 7 more names

إجيراتم

Fluffy blue pompoms on low mounds, on Dubai Municipality's seasonal list: plant October to February in sun and enjoy it through the cool months. Reported to poison cattle, so keep pets and livestock away.

Mature size0.15–0.3 m tall, 0.2–0.3 m spreadGrowthModerateSunSun/part shadeWaterModerate

Heat: 2 of 5

Salt: 2 of 5

Drought: 3 of 5

Shade: 3 of 5

Ease of care: 4 of 5

Use in a design Get it looked after

Also known as

The other names Ageratum is sold and searched under.

English names: Floss flower
Flossflower
Bluemink
Blue billygoatweed
Mexican ageratum
Botanical names: Ageratum mexicanum
Arabicالعربية: إجيراتم
أجريتم ajritum
مستديمة mustadima
Persianفارسی: گل ابری gol-e abri

Season

Through the Dubai year

How Ageratum behaves through Dubai's seasons, month by month.

JJan

FFeb

MMar

AApr

MMay

JJun

JJul

AAug

SSep

OOct

NNov

DDec

Avg high °C

24°

26°

29°

34°

38°

40°

42°

40°

36°

31°

27°

Cool-season planting window

Oct – Dec

Flowers through the cool months

Jan – Apr

Mildew, whitefly and aphids

Fades as the heat arrives

Apr – Jun

Cool-season planting window: Oct–Feb
Dubai Municipality names ageratum without giving a rotation; Abu Dhabi City Municipality lists it among its winter flowers. Shade new plants if October is hot.
Flowers through the cool months: Nov–Apr
NC State: flowers from spring to frost in cooler climates; in Dubai it fades as the heat arrives.
Mildew, whitefly and aphids: Dec–Feb
NC State: susceptible to powdery mildew; common pests are whiteflies and aphids. Overwatering invites phytophthora.
Fades as the heat arrives: Apr–Jun
A frost-tender summer annual in cooler climates (NC State); April's mean maximum in Dubai is 33.7 °C and May's 38.2 °C.

Ageratum's Dubai season follows the municipal rotations. Dubai Municipality plants its beds from September to October and tops them up from January to February, and home gardens can plant from October to February. In early October, with highs near 36 °C, plant in the evening and shade new plants for a week. It flowers from about November and carries through the coolest months, when mean highs are 24–31 °C. As April's mean maximum reaches 33.7 °C and May's 38.2 °C, the display fades and beds are cleared for summer bedding such as Vinca and Portulaca.

Meet the plant

Meet the Ageratum

Meet ageratum, the flower that looks like a puff of powder-blue smoke. The tassel-like flower heads of pale to deep blue, violet, pink or white sit in tight clusters above low mounds of soft green leaves. NC State says the genus name comes from Greek words meaning 'not old age', because the flowers hold their colour so long.

It is a quiet professional of the public bed. Dubai Municipality named ageratum among its seasonal flowers in 2016 (Emirates 24|7) and again in 2020 (Al Bayan), and Abu Dhabi City Municipality's list of winter flowers includes it as well. Its job is the cool blue that makes red salvia and orange marigold look hotter.

It is also a plant to keep in its place. It is a bedding flower, not a salad or a pasture plant: the ASPCA has no entry for it, and a 1989 veterinary paper reports natural and experimental poisoning of cattle by Ageratum houstonianum.

Ageratum houstonianum is a frost-tender herbaceous annual, half to one foot (15–30 cm) tall and a similar width, forming clumping mounds of fluffy, aster-like flowers in blue, pink or white (NC State, RHS). The flowers are tubular and tassel-like, which gives the characteristic 'floss' look. NC State says it flowers from spring to frost and is good in beds and containers, with taller varieties making good cut flowers. RHS lists the common name flossflower.

In Dubai it belongs to the municipal bedding list. Dubai Municipality names Ageratum among its seasonal flowers in 2016 (Emirates 24|7) and 2020 (Al Bayan, which gives the Arabic «الإجيراتم»), and Abu Dhabi City Municipality lists it among the winter flowers planted along its roads (Al Ittihad, 2020). Neither Dubai source gives an exact planting date, so this page uses the cool season, October to February, that Dubai's rotations (September to October, then January to February) cover.

It likes full sun but tolerates part shade (NC State), and a rich, moist, well-drained soil. NC State rates it moderately drought tolerant. Its weak points are powdery mildew and, in wet soil, phytophthora root rot: NC State names 'Blue Danube' and 'Blue Horizon' as cultivars with excellent resistance to phytophthora, and RHS gives 'Blue Danube' its Award of Garden Merit. In Dubai's sand, add compost for nutrients and water-holding, and keep the soil evenly moist but never soggy.

Design

Where to use it

Cool blue edgingMass beddingContainer fillerBedding contrast

Use ageratum as a cool-coloured front layer in a cool-season bed, in a drift of one blue, where it sets off warm flowers such as orange marigold and red salvia. NC State suggests it for edging or low massing in beds and for containers. Give it full sun or light afternoon shade and free-draining soil enriched with compost, and keep it within reach of a drip line, since it prefers moist soil.

Marigold

Marigold's warm orange and gold contrast with ageratum's cool blue, and both are named in Dubai Municipality's lists.

Salvia

Red salvia spikes rise above ageratum's low blue mounds; both are on Dubai Municipality's seasonal list.

Sweet alyssum

A white alyssum edge in front of blue ageratum, with the same planting window and the same municipal list.

Care guide

How to grow it in Dubai

Watering: Summer: Not grown outdoors through summer; clear it in April or May.
Winter: Keep evenly moist but not soggy: NC State says it prefers moist, well-drained soil and is moderately drought tolerant, and notes root rot problems in wet soil. Water at the base.
Establishment: Keep evenly moist for the first two weeks, with light shade if planted in a warm spell.
Soil: Rich, moist, well-drained soil in full sun or part shade (NC State). Mix compost into Dubai's sand for nutrients and water-holding.
Feeding: A light balanced feed every three to four weeks, because sand holds few nutrients.
Pruning: Deadhead to keep the mounds tidy and flowering; taller varieties can be cut for flowers (NC State).
Planting: Plant nursery seedlings from October to February, spaced 25–30 cm apart (NC State says 10–12 inches), in full sun or light afternoon shade.
Pests: Powdery mildewWhiteflyAphidsPhytophthora root rot in wet soil

The care steps and the full guide, in WhatsApp. You pick who gets them.

Avoid these

Common mistakes

Keeping the soil wet. NC State links the plant to phytophthora root rot and names resistant cultivars; water at the base and let the surface dry slightly.
Letting it dry out completely. NC State says it prefers rich, moist soil and is only moderately drought tolerant.
Planting it in dense shade or in a crowded bed. NC State asks for full sun or partial shade and 10–12 inches of space, which also reduces powdery mildew.
Letting pets, grazing animals or children chew it. A 1989 veterinary paper reports poisoning of cattle, and there is no source calling it safe.
Expecting it to last through summer. It is a frost-tender annual, and Dubai's April and May heat ends the display.

Extra notes

Good to know

Dubai Municipality's list uses the Latin name Ageratum (Emirates 24|7, 2016) and the Arabic «الإجيراتم» (Al Bayan, 2020); Abu Dhabi's list spells the Arabic «أجريتم».
NC State names 'Blue Danube' and 'Blue Horizon' as cultivars with excellent resistance to phytophthora, and RHS gives 'Blue Danube' an Award of Garden Merit.
RHS lists Ageratum mexicanum and Ageratum caeruleum among the older names for this species, and gives the common name flossflower.
Wikipedia notes that Ageratum houstonianum can become an invasive weed when grown outside its native range. We found no report of that in the UAE, but deadheading limits seed.

Toxicity: There is no ASPCA entry for ageratum, and NC State's Plant Toolbox page for it carries no toxicity information, so it is unassessed for pets. A 1989 veterinary paper (Revista Cubana de Ciencias Veterinarias, via FAO AGRIS) reports natural and experimental poisoning of cattle by Ageratum houstonianum, and Wikipedia says it contains pyrrolizidine alkaloids that are toxic to grazing animals and cause liver lesions. Do not eat it, do not feed it to animals, and keep pets and children away from it.

Pros

Cool blue pompoms that hold their colour a long time (NC State)
On Dubai Municipality's seasonal flower list
Low, tidy mounds for edging, beds and pots
Moderately drought tolerant, and relatively pest-free (NC State)
Phytophthora-resistant cultivars exist, such as 'Blue Danube' and 'Blue Horizon'

Cons

Reported to poison grazing animals; not a safe plant to eat
No Dubai source gives a planting window
Susceptible to powdery mildew and to root rot in wet soil
Frost-tender annual that fades in Dubai's spring heat

FAQ

Common questions

When should I plant ageratum in Dubai?

From October to February. Dubai Municipality names ageratum among its seasonal flowers without giving a rotation, and Abu Dhabi City Municipality lists it among its winter flowers. Shade new plants if October is still hot.

Is ageratum safe for pets?

It is unassessed: there is no ASPCA entry. A 1989 veterinary paper reports poisoning of cattle by Ageratum houstonianum and Wikipedia notes pyrrolizidine alkaloids that damage the liver in grazing animals, so keep pets and livestock from eating it.

Why did my ageratum stop flowering in April or May?

NC State describes it as a frost-tender annual that flowers from spring to frost in cooler climates; in Dubai the mean maximum reaches 33.7 °C in April and 38.2 °C in May, which ends the display. Replace it with heat-tolerant bedding.

What does ageratum need?

NC State says full sun or partial shade and rich, moist, well-drained soil, with moderate drought tolerance. Keep it moist but not soggy; it is susceptible to powdery mildew, and phytophthora root rot is the risk in wet soil.

Is floss flower the same as ageratum?

Yes. Floss flower (or flossflower) is the English name for Ageratum houstonianum, and bluemink and blue billygoatweed are other names (NC State).

Not sure how it suits your garden?

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Sources

Last reviewed 2026-10-29 by Plant Guide horticulture desk.

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