Here’s what I learned about Zinnias the hard way:
Don’t spray the leaves!
Unfortunately, I let the sprinkler spray my Zins, and they got powdery mildew on the leaves. Which I then had to treat all summer. Once you get it, it’s tough to get rid of it. Powdery mildew looks like the name, powdery spots on the leaves. You can’t wipe it off, and if you don’t take care of it, your plants can die. You have to cut those parts off and throw them in the trash, not compost. Diseased plants can’t be composted because it can infect all of your compost.
Milk was actually the best medicine for my plants!
I mixed up a spray bottle of ½ milk and ½ water and a little bit of dish soap and sprayed the leaves daily for a few weeks to fight off the infection. I also use this for my roses to fight off aphids and Japanese beetles.
The last thing I learned was that you MUST cut the flowers!!!
I don’t like cutting my flowers because I like to see them out in my garden. But Zins love to be used as cut flowers. Cutting them stimulates them to grow new flowers and grow better.
I didn’t cut my zinnias enough, and some of my plants just didn’t flower as much as the ones that I cut. They also were leafier and shorter than the ones that were cut. Cutting also makes sure there is enough air circulation and stops them from producing seeds too early. Cutting them before they bloom will give you the longest vase life.