Posted: 06/07/2014 at 17:17
I would wait and plant in the early spring. They won't establish well in hot dry weather.
You could sow some Pak choi now - they germinate and grow quickly and you'll get a harvest of young leaves in about 30 days, and it should be developing hearts some 15 days later. It's hardier than it looks and will continue to give you a crop into late autumn.
I've just sown another couple of rows of Swiss chard - I'll be picking that in mild spells through the winter and well into the spring.