Sulfur Cosmos (Cosmos sulphureous) are a wonderful addition to the natural dye garden. The bright orange flowers have a sweet peppery smell and are a pollinators delight. Of all the flowers I grow, sulfur cosmos are the most pleasant to harvest because the plants grow to just the perfect chest height for harvesting—no bending required : )

Quick Facts:

Annual

Germination time: 7-14 days

Seed planting depth: 1/8”

Light: full sun

Spacing: 9-12”

Days to flower: 75-90

Plant height: 4-5’

CULTIVATION

I’ve experimented with both direct seeding into the garden and with transplanting and prefer the transplanting method for sulfur cosmos. The direct seed method works fine but transplanting gives me slightly earlier blooms. I start the seeds indoors under grow lights in early April about 8 weeks before our last average frost date and once the danger of frost has passed I transplant the seedlings out to the garden spacing them about 12” apart. The plants acclimate relatively quickly and begin to put out noticeable growth within 2-3 weeks.

HARVESTING

By late July the first blooms are happening and I begin harvesting right away to promote the plants to continue setting blooms. I harvest consistently every 2-3 days throughout the season until the frost comes along and puts a stop to it. Dedicated consistent harvesting yields the most blooms.

I plan to write a blog post soon to share how I dry and cure dye flowers so stay tuned for that. If you’re looking for information about natural dyeing with sulfur cosmos, I shared some of my favorite methods and dye flower recipes in this post, and for more extensive information about achieving the most colorfast shades and how to shift flower colors with iron and indigo you can purchase this recipe PDF I wrote. Be sure to check out all the dye flower seeds and natural dyes we offer in our shop. Link to our Sulfur Cosmos seeds below. Cheers!