Did a flat of perennials with my 7 yr old daughter Sunday. She was excited all week cause she likes planting the seeds. We did Coneflower, Rudbeckia, Daisy, Lupine, Foxglove, Delphinium, Yarrow and Hollyhock. I laid out the seed packs and she picked each row. Funny thing was her strategy was to go by seed size - small to large.
I bet by starting them early, some will bloom this year. And your daughter will develop a lifelong passion for gardening! I started Rudbeckia, Echinacea, Coreopsis, oregano, thyme, Gaillardia, and carnations so far. It's fun watching them grow.