I planted wildflowers (annuals) this year for the first time, they include zinnia, black eyed susan and many others that I'm unfamiliar with. Presently, they are still blooming but winter will be here in a few short weeks. What should I do to put my wildflower bed to sleep for the winter? Do I let the plants stay under the snow and remove the mess in the spring? Do I pull up all the plants, put down mulch and wait til spring?

Thanks for your help!