Zinnias have brown lower leaves, near the base of the stem.
I bought some Zinnias from a nursery 3 days ago and the bottom leaves have stayed brown. Should I cut them off? I can tell the plants are healthy as a bud of a zinnia blossomed into a very pretty red flower and all the upper leaves are gorgeous, while the bottom are icky. This has occurred in all of my 6 zinnia plants. I have avoided watering the bottom leaves as much as possible as well. Remove or let them be?
The plant looks healthy overall. Bottom leaves that get shaded as the plant grows often turn yellow, then brown. They are "senescing", a nice term for getting old. Once a green leaf has turned yellow, it is no longer capable of photosynthesis. I remove them for aesthetic reasons. Fighting off diseases and bugs is an on-going battle for commercial growers. Removing off-colored foliage reduces the chance of infecting more leaves. Keep annuals healthy by watering regularly and giving them fertilizer. Don't crowd zinnias; they need good air circulation since they are prone to powdery mildew in hot, dry weather.