# Cosmos (Cosmos bipinnatus)

Canonical: https://plantguide.ae/plants/cosmos · Updated: 2026-10-05
Source: Ghaf Gardens (https://plantguide.ae/plants/cosmos)

Cosmos · also called Garden cosmos, Mexican aster  
flower · exotic · family Asteraceae · grows 0.6–1.5 m tall, 0.3–0.6 m wide · fast growth  
full sun · low water need  
Ratings for Dubai (1–5, 5 is best): heat 3 · salt 2 · drought 4 · shade 1 · ease of care 4  
Sow or plant: Oct–Dec  
Uses: bedding, container

A feathery-leaved annual with wide, simple daisies, sown from seed between October and December; it flowers from midwinter to April and asks very little once up.

## About

Meet cosmos, the annual that makes a bed look as though it was sown by the wind. Feathery, thread-fine foliage forms a soft green haze, and above it single daisies in white, pink and crimson float on stems so slender that they seem to hover and nod at every passing breath of air.

That lightness is technical as much as pretty. The finely divided leaves let light and air pass through, so a bed of cosmos never reads as a solid block, and a stand 1.5 m tall still lets you see the wall behind. It is the opposite of a clipped, heavy hedge, and the contrast is the point.

In Dubai it belongs to the cool months, sown from seed in October and gone by April. The mood is relaxed and cottage-like, informal and generous: a plant for a cutting patch or the soft back layer of a border, not a formal edge. It asks for sun, lean soil and little water, and gives its flowers freely.

Cosmos bipinnatus is a Mexican annual with finely cut, almost thread-like leaves, which is what 'bipinnate' means: leaves divided twice. They hold single, wide-open daisies in white, pink, magenta and crimson on tall, wiry stems. The result is a plant that moves in a breeze and lets light through, so a stand of cosmos stays airy even at 1.5 m. The RHS describes it as a bushy annual that can reach 2.5 m, with flowers up to 8 cm across and a yellow central disc.

In Dubai, seed sown in place from October to December flowers in roughly two months and carries on to about April. NC State rates cosmos as heat and drought tolerant once established, and the RHS notes that plants will not flower in shade. The hot months end its season: plants left past April decline in the heat, and tall plants from late sowings grow leggy before they flower. Cosmos sulphureus, the orange 'yellow cosmos', is usually described as better in heat and humidity if you want to push the season.

Cosmos is a low-input plant, and the common mistake is to over-care for it. Rich soil and generous feeding give tall, leafy plants with few flowers; too much water makes them flop. A lean, free-draining bed in full sun, a few twiggy supports for tall types and regular deadheading keep it flowering, as the RHS advises. Leave a few seedheads to ripen at the end of the season if you want volunteers: NC State notes the plants readily reseed, and the seedlings will appear in the next cool season.

## Through the year

Cosmos has a short, easy Dubai season. Sow seed from October to December, directly where it will grow, pressing it into loose soil and keeping it moist until seedlings are up in one to three weeks. Plants grow quickly through November and December, and flowers open from about December, peaking from January to March when highs are 24–29 °C. Deadhead through winter to keep it flowering. By April, as highs reach 33 °C, flowering slows, and by May plants are tired and are cleared for summer bedding such as [Vinca](https://plantguide.ae/plants/vinca.md) and [Portulaca](https://plantguide.ae/plants/portulaca.md).

| When | What | Note |
| --- | --- | --- |
| Oct–Dec | Sow: Sow seed where it will flower | Press seed into loose soil, barely covered, and keep moist until it germinates in 1–3 weeks. |
| Dec–Apr | Flowers: Flowers from midwinter to spring | Deadhead regularly to prolong the display. |
| Jan–Mar | Prune: Deadhead and stake | Cut spent flowers to a side bud; support tall stems with twiggy canes. |
| May–Aug | Heat stress: Declines in the heat | Plants are cleared in April–May; summer sowings struggle. |

## Care in Dubai

- **Watering in summer:** Not grown outdoors through summer; it is a cool-season annual in Dubai.
- **Watering in winter:** Once established, water deeply once or twice a week by drip; excess water gives soft, floppy growth and fewer flowers.
- **While establishing:** Keep the seedbed moist for 5–10 days after sowing, then water deeply every few days until seedlings are 15 cm tall.
- **Soil:** Moderately fertile, free-draining soil in full sun; avoid both heavy, wet ground and very rich ground, which gives leaf instead of flower.
- **Feeding:** Little or none beyond compost at sowing; a single balanced feed at around six weeks if growth looks pale.
- **Pruning:** Pinch the tip of young plants once to encourage branching; deadhead to prolong flowering; stake tall types.
- **Planting:** Sow seed directly from October to December, barely covered, 30–45 cm apart; it germinates in one to three weeks. Nursery seedlings can be planted out from October.
- **Pests and problems:** Aphids; Powdery mildew in humid spells; Stem rot in wet soil
- **Toxicity:** Not known to be significantly toxic to people or pets.

## Good and bad

**Pros**
- Airy, long-flowering colour from midwinter to April for very little effort
- Easy and cheap from seed sown straight into the bed
- Tolerates poor, dry soil once established
- Reseeds if allowed, and makes a good cut flower
- Attracts pollinators, including bees and butterflies

**Cons**
- Finishes with the heat in April–May and cannot be kept through summer
- Tall types flop in rich soil or wind and need staking
- Aphids and powdery mildew can appear in humid spells
- Looks untidy once flowering slows, so clear it promptly

## Common mistakes

- Planting it in rich, heavily fed soil. It produces tall, leafy plants with few flowers and flops; cosmos does best on lean ground.
- Overwatering. Established cosmos is drought tolerant, and wet soil gives soft, floppy growth that needs staking.
- Sowing too deep. Seed should be barely covered; deep sowing slows or prevents germination.
- Sowing late in the season and expecting a long display. Seed sown after December has little time before the heat arrives in April.
- Leaving it too long once flowering stops. A tired, seed-heavy bed looks untidy; clear it and replant for summer.

## Good to know

- The RHS describes Cosmos bipinnatus as a tall, bushy annual that can reach 2.5 m; garden cultivars are usually shorter, and dwarf series are available.
- NC State rates it as heat and drought tolerant once established and notes that it readily reseeds, which is why deadheading is optional.
- Cosmos sulphureus, the orange or yellow cosmos, is generally described as better in heat and humidity, and is the species to try if you want to push the season.
- It is a useful pollinator plant: NC State notes that it attracts bees, butterflies and birds.

## Using it in a garden

Roles: Cottage-style winter bedding, Cut flower, Self-seeding filler, Pollinator planting

Sow cosmos in full sun in a lean, free-draining bed rather than your richest soil, and use it in the soft, back-of-border layer or in a cutting patch where its height is welcome. It suits informal planting; in a formal scheme use it behind lower bedding, with a few bamboo canes or twiggy supports for the tallest types. Sow in drifts, thin to 30–45 cm and let the stems intermingle. Because it is gone by May, plan the following summer bedding in the same bed.

- [Marigold](https://plantguide.ae/plants/marigold.md): Marigold's compact orange and gold pompoms sit well in front of cosmos's airy stems, with the same October timing and similar water needs.
- [Zinnia](https://plantguide.ae/plants/zinnia.md): Zinnia is another cut-flower annual from Dubai Municipality's bedding list, giving a denser, bolder bloom to contrast with cosmos's lightness.
- [Snapdragon](https://plantguide.ae/plants/snapdragon.md): Snapdragon's upright, formal spikes give structure among cosmos's looser, wiry stems in a mixed cool-season border.
- [Sunflower](https://plantguide.ae/plants/sunflower.md): Sunflower provides the tall, bold back layer, with cosmos filling the middle in the same October sowing window.

## FAQ

**When should I sow cosmos in Dubai?**  
From October to December, directly where it will flower. Seed germinates in one to three weeks, and flowers open from around December.

**Can cosmos grow in a Dubai summer?**  
Not reliably. It is drought and heat tolerant once established, but Dubai's cool-season sowing gives the best results, and the display ends in April–May. Cosmos sulphureus is the species to try for warmer weather.

**Why is my cosmos tall and floppy with few flowers?**  
Usually rich soil, too much feeding or too much water. Cosmos does best on lean, free-draining ground with little water once established.

**Does cosmos come back by itself?**  
It reseeds readily, according to NC State, so leaving a few seedheads at the end of the season gives volunteer seedlings in the next cool season.

**Is cosmos good for cutting?**  
Yes. The RHS notes that it provides flowers for cutting over a period of months, and cutting regularly also keeps the plant flowering.

## Related plants

[Marigold](https://plantguide.ae/plants/marigold.md) · [Zinnia](https://plantguide.ae/plants/zinnia.md) · [Snapdragon](https://plantguide.ae/plants/snapdragon.md) · [Sunflower](https://plantguide.ae/plants/sunflower.md)

## Photos

![Cosmos bipinnatus pink flower. Taken at Burdwan, West Bengal, India.](https://upload.wikimedia.org/wikipedia/commons/9/9c/Cosmos_bipinnatus_pink%2C_Burdwan%2C_West_Bengal%2C_India_10_01_2013.jpg)  
Photo: Joydeep / CC BY-SA 3.0 / Wikimedia Commons ([source](https://commons.wikimedia.org/wiki/File:Cosmos_bipinnatus_pink,_Burdwan,_West_Bengal,_India_10_01_2013.jpg))

![Blueten 002 2021 08 23](https://upload.wikimedia.org/wikipedia/commons/1/1e/Blueten_002_2021_08_23.jpg)  
Photo: Friedrich Haag / CC BY-SA 4.0 / Wikimedia Commons ([source](https://commons.wikimedia.org/wiki/File:Blueten_002_2021_08_23.jpg))

![Cosmos bipinnatus (Family: Asteraceae). Common mames: garden cosmos or Mexican aster. Andrena sp. (Andrenidae) bee.](https://upload.wikimedia.org/wikipedia/commons/5/54/Cosmos_bipinnatus_%28Asteraceae%29_with_an_Andrena_sp._bee.jpg)  
Photo: Juan Carlos Fonseca Mata / CC BY-SA 4.0 / Wikimedia Commons ([source](https://commons.wikimedia.org/wiki/File:Cosmos_bipinnatus_(Asteraceae)_with_an_Andrena_sp._bee.jpg))

![A Monarch Butterfly (Danaus plexippus) feeding on a Mexican Aster (Cosmos bipinnatus) at a Garden in Baltimore County...](https://upload.wikimedia.org/wikipedia/commons/e/ec/Monarch_Butterfly_on_a_Mexican_Aster_in_Maryland.jpg)  
Photo: Hrlabel / CC BY-SA 4.0 / Wikimedia Commons ([source](https://commons.wikimedia.org/wiki/File:Monarch_Butterfly_on_a_Mexican_Aster_in_Maryland.jpg))

## Sources

- [RHS: Cosmos bipinnatus](https://www.rhs.org.uk/plants/30717/cosmos-bipinnatus/details)
- [NC State Extension Gardener Plant Toolbox: Cosmos bipinnatus](https://plants.ces.ncsu.edu/plants/cosmos-bipinnatus/)
- [Kew Plants of the World Online: Cosmos bipinnatus](https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:198320-1)
- [Acacia Garden Center: Dubai Garden Calendar](https://acaciagardencenter.com/blogs/blog/dubai-planting-calendar)