In NC we can grow greens easily from fall, through winter and spring.
Summertime--not so much.
But there is one green that we grow year-round and use for salads, sandwiches, sauteeing and soups.
It's a relative of beets, but doesn't have an edible root. The stems have been cultivated to grow in a variety of colors--red, yellow, orange, white. The young leaves are best for fresh eating and the larger leaves for cooking.
Can be cooked like spinach or any other green: simmer some onions and garlic in butter and/or olive oil, then add cut-up chard leaves till they just collapse, but still have a nice bright color. Serve. Or add to a quiche or use instead of spinach in a lasagna.
I've been planting more vegetables with longer lives that are biennials, like chard, or perennials to reduce the amount of time I spend planting and re-planting beds.
Chard is a biennial, which means it'll live through one or two summers and one or two winters depending on what season it's planted. You'll know it has run its course when it gets leggy and sends up a shoot of modest flowers.
Chard seeds are a bit smaller than pea seeds, so easy handling for kids. I soak the seeds overnight in a bowl so they can soak up some water to help them germinate. They'll germinate outdoors in spring, summer or fall unless it's very hot. Plant them as a group a few inches apart if you want to harvest them young as salad greens with scissors. Or put them a foot apart if you want to hand pick leaves for both cooking and fresh-eating.
Sometimes Chris puts an individual plant at the center of a bed of carrots or lettuce for visual impact like the dimple in Mona Lisa's smile. I also use chard in container plantings so its big leaves contrast with finer, fernier leaves.
And there's no law against using chard in a perennial bed or a bed of annuals--it's pretty enough--and always there for healthy snacking. Goes well with wine or beer as you knock out a few one-handed garden tasks after work.