I'm guessing what they really mean is that you should dead head them...to keep them from using their energy to set seed. Just pull or clip off the flowers after they've faded...should keep them blooming all summer.

Scott

Thanks Scott! I've been diligently deadheading most of my flowers everyday.

So they do bloom all summer?

This is my first year growing them, and honestly, they grow like weeds. The tallest flower stalk is about 4' tall. I bought these as young plants about a month ago.

I'm glad I really like Cosmos! lol I do have a batch of Pink or White one's coming up that I planted, so it will be interesting to see how they do. The leaves on them are more fern like than the yellow ones.

Oak, only my second year to try cosmos and zinnia from seed. They're both so easy to grow. Love picking small bouquets for the kitchen window.

Oh yeah! I've actually never tried the orange and yellow variety, but they are just like their pink and purple brethren...they will bloom right up until the first frost cuts them down...and they will fall to the first frost, they are very tender. Other than that thought, just keep them watered at the base (try not to get leaves wet...i've had them get bad mildew before if it's really humid) and keep them dead headed and they will not dissapoint...for the money, I'd say they are pretty much the most bang for the buck!

Natal, I am totally shocked at how easy Zinnias are to grow! Last year I planted the multi-colored miniature ones and they bloomed all summer.

This year I planted two of the larger varieties, a burnt red in color, and they've been in the ground for at least three weeks and not ONE of the flowers have died yet, and they're still producing new flowers!

I think people are scared to grow them because they look hard to grow. lol

BTW, are they easy to plant from seed like Cosmos are?

Yup.
loosen the soil, sprinkle on, water the seeds in, and keep moist until they sprout. Water only occasionally after that, but deeply. But do not get water on the leaves - water them by running water slowly on the ground under them. Put wheat straw under them to prevent dirt from splashing up on the leaves when it rains. The powdery mildew is in the soil, so if it gets on the leaves, it will spread like wildfire and infect your plants. If you cheat ONE TIME, and water them by spraying them, you will risk them getting Powdery Mildew, just like the cosmos, as Scotty said. Trust me on this. You'll be sorry if you do. The flowers will still look pretty, but the leaves will get all white and moldy looking and ruin the whole thing.

If any of the plants get it, pull that plant out and burn it! Then wash your hands or gloves thoroughly to prevent it from spreading to other plants.

~Annie