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Flower Full Sun Low water

Cosmos

Written by the GrowByCity Editorial Team · Updated April 2026
2 min read

Airy, delicate flowers on tall stems. A warmth-loving plant that does best between 15°C and 28°C, cosmos adapts well to tropical and subtropical conditions but cannot tolerate frost. Plant in a spot with full sun (6-8 hours of direct light daily) and provide minimal watering — it prefers dry conditions between drinks. Expect blooms in approximately 50-60 days. A magnet for pollinators, it supports bees, butterflies, and beneficial insects while brightening your garden.

Harvest 50-60 days
Temp Range 5°C — 35°C

Quick Answer: How to Grow Cosmos

Cosmos takes 50-60 days to harvest. It grows best in 15–28°C with full sun and low watering. Cosmos is not frost tolerant — wait until after the last frost to plant. It can be grown in 350 cities worldwide.

Find the best time to plant Cosmos in your city →

Growing Requirements

☀️
Sun
Full Sun
💧
Water
Low
❄️
Frost
Sensitive
📅
Harvest
50-60 days

Temperature Range

15-28°C
-10°C 45°C
Optimal: 15–28°C Tolerates: 5–35°C
Tropical suitable: Yes
Cities growing: 350 of 350

Growing Tips

💡

Expert Tips

Direct sow. Thrives on neglect -- don't fertilize. Wait until soil warms to at least 15°C before transplanting outdoors — cold soil stunts growth and can invite root rot. Overwatering is the most common mistake. Let soil dry out between waterings and ensure drainage is excellent.

Quick Facts

  • Grows in 350 of 350 cities
  • Available in 7 regions worldwide
  • Temperature range: 5°C to 35°C
  • Optimal growing: 15°C to 28°C
  • Harvest in 50-60 days

Did You Know?

  • 🌱 Cosmos loves the heat! It thrives in tropical and subtropical climates year-round.
  • 🌱 Cosmos needs at least 6-8 hours of direct sunlight daily for optimal growth.
  • 🌱 Cosmos is drought-tolerant — perfect for gardeners who tend to forget watering!

Step-by-Step Growing Guide

Cosmos thrives in poor to average, well-drained soil with a pH of 6.0–8.5 — unlike most flowering annuals, it actively declines in rich, amended soil, producing massive foliage at the expense of flowers. Do not add compost or fertilizer to the planting area. Direct sow seeds after last frost date, pressing them into the soil surface and covering with just 1/4 inch of soil. Thin to 12–18 inches apart once seedlings are 2 inches tall. Cosmos handles dry conditions remarkably well — water only when the top 2 inches of soil are completely dry, roughly every 7–10 days in summer. Overwatering is the most common mistake. No fertilizer is needed or wanted. In very long-summer climates, succession-sow every 3–4 weeks for continuous bloom. Plants grow 3–5 feet tall and may need staking in exposed, windy sites. Self-seeding is prolific — allow a few plants to set seed at season's end for a volunteer crop next year.

Common Pests & Problems

Aster yellows (phytoplasma disease) causes distorted, yellowed growth with stiff, brush-like abnormal flower heads — there is no cure; remove infected plants immediately and control leafhoppers that spread it with row covers early in the season. Powdery mildew appears late in the season on lower leaves in humid conditions — it's largely cosmetic at that stage, but if caught early, remove affected leaves and improve airflow. Aphids occasionally colonize stem tips — a strong jet of water is sufficient to dislodge them; avoid fertilizing with nitrogen as this draws aphid infestations. Botrytis can collapse spent flowers in wet weather — deadhead consistently to prevent this. Cosmos is otherwise remarkably trouble-free, which is the core of its garden value.

Harvest & Storage

Cut cosmos for vases when flowers are in half to three-quarter bud — fully open flowers shatter quickly after cutting. Harvest in the morning, cut long stems, and immediately place in cool water. Remove lower leaves to prevent rot. Vase life is 5–8 days. For seed saving, allow selected stems to fully mature and dry on the plant — seeds are ready when the petals have fallen and the seed heads are dry and brown. Store seed in a paper envelope in a cool, dry location; viability holds for 3 years.

Popular Varieties

'Sensation' is the classic tall mix reaching 4–5 feet with large, single pink, white, and crimson flowers — the benchmark garden cosmos. 'Purity' is a pure white single-flowered selection prized by flower farmers and brides for its elegant simplicity. 'Rubenza' offers deep ruby-red blooms that hold color better than most red cosmos in heat and fade gracefully to a warm rose. 'Double Click' series produces fully double, pompom-like flowers in a range of shades, a novelty departure from the typical single-flowered type.

Where to Grow Cosmos

Cosmos can be grown in 350 cities across 7 regions worldwide

🌍 Europe (80 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Aarhus, DK easy
Amsterdam, NL easy
Ankara, TR easy
Antalya, TR easy
Athens, GR easy
Barcelona, ES easy
Bari, IT easy
Belgrade, RS easy
Bergen, NO easy
Berlin, DE easy
Bilbao, ES easy
Bologna, IT easy
Bordeaux, FR easy
Bratislava, SK easy
Brussels, BE easy
Bucharest, RO easy
Budapest, HU easy
Catania, IT easy
Cologne, DE easy
Copenhagen, DK easy
Corfu, GR easy
Cork, IE easy
Dublin, IE easy
Dubrovnik, HR easy
Edinburgh, GB easy
Florence, IT easy
Frankfurt, DE easy
Gdansk, PL easy
Genoa, IT easy
Glasgow, GB easy
Gothenburg, SE easy
Hamburg, DE easy
Helsinki, FI easy
Heraklion, GR easy
Istanbul, TR easy
Izmir, TR easy
Krakow, PL easy
Kyiv, UA easy
Limassol, CY easy
Lisbon, PT easy
Ljubljana, SI easy
London, GB easy
Lyon, FR easy
Madrid, ES easy
Malaga, ES easy
Marseille, FR easy
Milan, IT easy
Munich, DE easy
Naples, IT easy
Nice, FR easy
Nicosia, CY easy
Oslo, NO easy
Palermo, IT easy
Paris, FR easy
Porto, PT easy
Poznan, PL easy
Prague, CZ easy
Reykjavik, IS easy
Riga, LV easy
Rome, IT easy
Seville, ES easy
Sofia, BG easy
Split, HR easy
Stockholm, SE easy
Strasbourg, FR easy
Stuttgart, DE easy
Tallinn, EE easy
Thessaloniki, GR easy
Tirana, AL easy
Toulouse, FR easy
Turin, IT easy
Turku, FI easy
Valencia, ES easy
Valletta, MT easy
Verona, IT easy
Vienna, AT easy
Vilnius, LT easy
Warsaw, PL easy
Zagreb, HR easy
Zurich, CH easy

🌏 Asia (79 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Ahmedabad, IN easy
Almaty, KZ easy
Bali, ID easy
Bandung, ID easy
Bangalore, IN easy
Bangkok, TH easy
Beijing, CN easy
Busan, KR easy
Cebu, PH easy
Chandigarh, IN easy
Chengdu, CN easy
Chennai, IN easy
Chiang Mai, TH easy
Chittagong, BD easy
Chongqing, CN easy
Coimbatore, IN easy
Colombo, LK easy
Da Nang, VN easy
Dalian, CN easy
Davao, PH easy
Delhi, IN easy
Dhaka, BD easy
Dharan, NP easy
Fukuoka, JP easy
Galle, LK easy
Guangzhou, CN easy
Hangzhou, CN easy
Hanoi, VN easy
Harbin, CN easy
Ho Chi Minh City, VN easy
Hong Kong, HK easy
Hyderabad, IN easy
Incheon, KR easy
Indore, IN easy
Islamabad, PK easy
Jaipur, IN easy
Jakarta, ID easy
Jeju, KR easy
Johor Bahru, MY easy
Karachi, PK easy
Kathmandu, NP easy
Kochi, IN easy
Kolkata, IN easy
Kuala Lumpur, MY easy
Kunming, CN easy
Kyoto, JP easy
Lahore, PK easy
Lucknow, IN easy
Manila, PH easy
Mumbai, IN easy
Nagoya, JP easy
Nanjing, CN easy
Nha Trang, VN easy
Okinawa, JP easy
Osaka, JP easy
Pattaya, TH easy
Penang, MY easy
Phnom Penh, KH easy
Pune, IN easy
Sapporo, JP easy
Seoul, KR easy
Shanghai, CN easy
Shenzhen, CN easy
Siem Reap, KH easy
Singapore, SG easy
Surabaya, ID easy
Surat, IN easy
Taipei, TW easy
Tashkent, UZ easy
Tbilisi, GE easy
Tokyo, JP easy
Ulaanbaatar, MN easy
Varanasi, IN easy
Vientiane, LA easy
Visakhapatnam, IN easy
Wuhan, CN easy
Xi'an, CN easy
Xiamen, CN easy
Yangon, MM easy

🌎 North America (78 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Albuquerque, US easy
Anchorage, US easy
Atlanta, US easy
Austin, US easy
Baltimore, US easy
Baton Rouge, US easy
Boise, US easy
Boston, US easy
Bridgetown, BB easy
Buffalo, US easy
Calgary, CA easy
Cancun, MX easy
Charleston, US easy
Charlotte, US easy
Chattanooga, US easy
Chicago, US easy
Denver, US easy
Des Moines, US easy
Detroit, US easy
Edmonton, CA easy
El Paso, US easy
Fargo, US easy
Fresno, US easy
Guadalajara, MX easy
Halifax, CA easy
Hartford, US easy
Havana, CU easy
Honolulu, US easy
Houston, US easy
Jacksonville, US easy
Kansas City, US easy
Kingston, JM easy
Knoxville, US easy
Las Vegas, US easy
Little Rock, US easy
Los Angeles, US easy
Louisville, US easy
Lubbock, US easy
Madison, US easy
Memphis, US easy
Mexico City, MX easy
Miami, US easy
Milwaukee, US easy
Minneapolis, US easy
Monterrey, MX easy
Montreal, CA easy
Nashville, US easy
New Orleans, US easy
New York, US easy
Oaxaca, MX easy
Oklahoma City, US easy
Omaha, US easy
Ottawa, CA easy
Panama City, PA easy
Phoenix, US easy
Pittsburgh, US easy
Portland, US easy
Puebla, MX easy
Quebec City, CA easy
Raleigh, US easy
Richmond, US easy
Sacramento, US easy
Salt Lake City, US easy
San Diego, US easy
San Francisco, US easy
San Jose, CR easy
Santo Domingo, DO easy
Saskatoon, CA easy
Savannah, US easy
Seattle, US easy
Spokane, US easy
St. Louis, US easy
Tampa, US easy
Toronto, CA easy
Tucson, US easy
Vancouver, CA easy
Victoria, CA easy
Winnipeg, CA easy

🌍 Africa (39 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Abidjan, CI easy
Accra, GH easy
Addis Ababa, ET easy
Algiers, DZ easy
Antananarivo, MG easy
Arusha, TZ easy
Bamako, ML easy
Bloemfontein, ZA easy
Cairo, EG easy
Cape Town, ZA easy
Casablanca, MA easy
Dakar, SN easy
Dar es Salaam, TZ easy
Douala, CM easy
Durban, ZA easy
Entebbe, UG easy
Fez, MA easy
Freetown, SL easy
Harare, ZW easy
Johannesburg, ZA easy
Kampala, UG easy
Kigali, RW easy
Kinshasa, CD easy
Lagos, NG easy
Libreville, GA easy
Lilongwe, MW easy
Lome, TG easy
Luanda, AO easy
Lusaka, ZM easy
Maputo, MZ easy
Marrakech, MA easy
Mombasa, KE easy
Nairobi, KE easy
Ouagadougou, BF easy
Port Louis, MU easy
Pretoria, ZA easy
Tunis, TN easy
Windhoek, NA easy
Zanzibar, TZ easy

🌎 South America (39 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Arequipa, PE easy
Asuncion, PY easy
Barranquilla, CO easy
Belem, BR easy
Bogota, CO easy
Brasilia, BR easy
Buenos Aires, AR easy
Cali, CO easy
Campinas, BR easy
Caracas, VE easy
Cartagena, CO easy
Concepcion, CL easy
Cordoba, AR easy
Curitiba, BR easy
Cusco, PE easy
Fortaleza, BR easy
Georgetown, GY easy
Goiania, BR easy
Guayaquil, EC easy
La Paz, BO easy
Lima, PE easy
Manaus, BR easy
Medellin, CO easy
Mendoza, AR easy
Montevideo, UY easy
Paramaribo, SR easy
Port of Spain, TT easy
Porto Alegre, BR easy
Quito, EC easy
Recife, BR easy
Rio de Janeiro, BR easy
Rosario, AR easy
Salvador, BR easy
Santa Cruz, BO easy
Santiago, CL easy
Sao Paulo, BR easy
Sucre, BO easy
Trujillo, PE easy
Valparaiso, CL easy

🌊 Oceania (19 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Adelaide, AU easy
Alice Springs, AU easy
Auckland, NZ easy
Brisbane, AU easy
Cairns, AU easy
Canberra, AU easy
Christchurch, NZ easy
Darwin, AU easy
Dunedin, NZ easy
Gold Coast, AU easy
Hamilton, NZ easy
Hobart, AU easy
Melbourne, AU easy
Noumea, NC easy
Perth, AU easy
Suva, FJ easy
Sydney, AU easy
Townsville, AU easy
Wellington, NZ easy

🕌 Middle East (16 cities)

City Level JanFebMarAprMayJunJulAugSepOctNovDec
Abu Dhabi, AE easy
Amman, JO easy
Baghdad, IQ easy
Beirut, LB easy
Doha, QA easy
Dubai, AE easy
Erbil, IQ easy
Jeddah, SA easy
Kuwait City, KW easy
Manama, BH easy
Muscat, OM easy
Riyadh, SA easy
Sana'a, YE easy
Tabriz, IR easy
Tehran, IR easy
Tel Aviv, IL easy

When should I plant cosmos in my city?

The best time to plant cosmos depends on your local climate zone. It thrives in temperatures between 15°C and 28°C. Wait until after the last frost in your area. Check your city's planting calendar on GrowByCity for exact dates.

Can I grow cosmos in winter?

Cosmos is not frost tolerant and cannot survive winter outdoors in most temperate climates. In tropical areas (USDA Zones 10+), it may grow year-round.

Get Cosmos Seeds & Plants

Ready to start growing? Find Cosmos seeds and starter plants online.

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Similar Growing Requirements

Frequently Asked Questions about Cosmos

When should I plant cosmos?

The best time to plant cosmos depends on your local climate. Cosmos grows best in temperatures between 15°C and 28°C (can tolerate 5°C to 35°C). Cosmos is not frost tolerant, so wait until after the last frost in your area. Check your city's planting calendar on GrowByCity for exact planting months.

Can cosmos grow in tropical climates?

Yes! Cosmos can grow in tropical climates. It's successfully grown in tropical cities like Abidjan, Abu Dhabi, Accra. Cosmos requires full sun and low watering.

How long does cosmos take to grow?

Cosmos typically takes 50-60 days from planting to harvest. It requires full sun and low watering. Direct sow. Thrives on neglect -- don't fertilize. Wait until soil warms to at least 15°C before transplanting outdoors — cold soil stunts growth and can invite root rot. Overwatering is the most common mistake. Let soil dry out between waterings and ensure drainage is excellent.

Find the Best Time to Plant Cosmos

See the planting calendar for Cosmos in these popular cities:

Last updated: March 2026 · Climate data from NOAA, FAO, USDA

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