I planted the annual cosmos from a seed packet and I was wondering when I can gather seeds from it to plant for next year? I've never gathered my own seeds before. How will I know? What will I be looking for? Any advice would be great!
The flowers will wither. Pull them just before they fall off. The seeds are obvious when you look at the flower.
Some varieties of cosmos may not come true from seed. The common yellow will for sure. In fact, it self-seeds prolifically. We have 3 crops every season just from the plant reseeding itself.
They are easy to collect - the petals will fall off and the seed heads will brown up. Birds will eat them then also.
Don't forget to shear your cosmos after each flush of blooms begin to fade to encourage repeat blooms till frost.
Those babies will go forth and multiply freely, very freely. If left un-deadheaded, the seeds will literally stick to anything they come in contact with, including you.
I bought a bunch of these seeds from someone who sells them on this website. I planted a bunch this spring and I'm noticing a lot of growth. I just can't tell if they will become large enough to flower in the summer.
Also, I would like to know what is the best way to "keep" the seeds I didn't use all of them this spring. Refrigerate?