Zinnia Question

Zinnia Question

My zinnia's have pretty much gone through their cycle. A lot of them are turning brown and dying. I was thinking of just letting them die and let them reseed. Is there anything I need to do or just let nature take its course? Or would it be better to pull them up and plant new ones? They look bad like this. Also if I cut/dead head the flowers will they produce more? And if so how far down should I cut? I'm in zone 9 btw.
Echinacea – bug

Echinacea – bug

mystery eggs, swallowtails and plant photos

mystery eggs, swallowtails and plant photos

Please tell me what this plant is?

Please tell me what this plant is?

My third season– and I still have plenty of questions, so this is kinda long..

My third season– and I still have plenty of questions, so this is kinda long..

Coleus

Coleus

Just moved in.

Just moved in.