It will stand through the winter. I always sow mine in about July.

For fun, you can buy mixed packets of red, yellow, orange and white stemmed chard, which look attractive, but they all taste the same.

The stems and the leaves are both edible but need different amounts of cooking - the leaves need virtually no time in just the amount of water still left on them after rinsing. If I'm eating both at the same meal, I usually break the stems up and cook in a small amount of water, and put the leaves on top to steam. That seems to work.