Spinach is a cool weather crop and will often bolt if the temperature is too hot. I recommend starting it indoors by seed and setting it in a sunny window if you have one.
Kale, which is a trendy green right now (in New York you can get kale and beets as a side these days), is a fantastic plant that can be grown most of the year. It loves colder weather and thrives if it has to survive a frost or two. The only time of year it doesn't love (because it bolts) is summer, but I have worked my way around that with shade.
I will be honest, because of my love of Mexican food salads, green onions need to be a staple around here. However, it obviously doesn't make sense to buy them in bulk. Well, thanks to Pinterest, I have learned the following trick.
Starting to regrowWhen you have cut all of the green tops off and just have the root left, stick your green onions in a cup of water and put them in a sunny window. Within just a few days, they will start growing back! Then you can just harvest them as needed. This ensures that I will never go without green onions for very long, plus - I don't have to buy them.