I'd stake it, but only last year's stems - this one flowers on the previous year's growth, and all the earlier stems from the year before that should be removed. Stake now, cut out what you need to in Spring as growth begins.

I use large link-stakes around mine to support them after they've flopped. You will need to prune out all the flowered shoots in late summer anyway, so it's kind of a 'self-cleaning' thing. Each shoot is biennial, it grows one year, then flowers the next spring.

Thanks SO much for that information - it was really helpful and I will give it a go!