Too late to dig in mustard green manure?

[FloweringRocket]

I'm a novice gardener and planted caliente mustard as green manure in a plot of tired soil earlier this summer. It has now flowered. Have I left it too late to dig in or can anyone advise on the best course of action now? The idea was to clean and freshen up the soil which had been in planters for years. Thanks for any advice!

[nickdub]

Cut down and compost the tops - dig in the roots, and sow something-else eg field beans.