Sulphur Cosmos

Orange and yellow flowers tinted with a touch of red. Great for your pollinator garden.

Crop Species: Cosmos sulphureus

Crop Family: Asteraceae 

Seed Story

Are the petals of a Cosmos flower more perfectly placed than those of any other flower? 

The folks who named Cosmos “Cosmos” were thinking along those lines since the Greek word cosmos means order and harmony.

Another name for Cosmos is Mexican aster. It is native to Mexico and Central America and then travelled to Spain in the 16th century before eventually becoming popular across Europe.

There are a number of Comos species out there.

You probably know Cosmos as the pink and violet and white flowers of the Cosmos bipinnatus species. They come in pinks and whites and violets. They are tall plants that are anything but orderly by the end of the growing season. 

Cosmos bipinnatus has frustrated me for years. Our season just doesn’t seem to be long enough to get a lot of viable seed before the frosts come in.

But then I met Cosmos sulphureus (a.k.a Sulphur cosmos) while walking the Tourne-Sol flower fields. As you can see from the picture, it is a cosmos of another colour.

I was stuck by those orange and yellow flowers tinted with a touch of red. 

And even more exciting - there was some seed on the flowers the crew had not cut for bouquets. This was much earlier than I was used to seeing cosmos seeds.

I harvested a handful of seeds and carried them back in my palm. The following year we sowed them in our garden. Now they are in our seed store.

I can’t vouch for whether Sulphur Cosmos will bring harmony to your garden but it sure does grow well.

HOW TO GROW

Planting Information

• Luminosity: Full Sun
• Seed Depth: 1/2”
• Germination Temperature: 20C - 30C
• Days to Germination: 7-10
• Earliest Planting Date: After frost. 
• Latest Planting Date: end June
• Days to maturity: 70 days
• Harvest period: early August - late September
• You can start Cosmos indoors or outdoors. Here are directions for both:

Directions To Start Indoors

Directions for Direct Seeding:

HOW TO KEEP SEEDS

• Cosmos is an annual plant that will produce seed its the first year
• Cosmos sulphureus will cross with other Cosmos sulphureus but not with Cosmos bipinnatus 
• Let a few flowers stay on the plant. The petals will dry down and leave a cluster of seeds.
• Harvest seed by hand.
• Pick out any sticks or flower bits.
• Let the seed dry a couple weeks before storing in a labelled envelope.
• Store seed in cool dry location