Raised bed preparation after beans!

You can grow runner beans year after year in the same soil. I prepare my runner bean bed in the autumn, dig out a trench and add loads of half composted kitchen waste. It's too late to do that now so just incorporate some well composted manure. You could just pile a few inches on top and let the worms do the work for you.

Sorry I've no idea about sunflowers in the same soil.

 

I've been growing beans on the same site for 40 years with no problem. I dig in well rotted garden compost each year and I get excellent results. You can just place it on the surface in the winter and it will be taken down by the worms.

Although I don't grow sunflowers this site has had sunflowers growing each year for at least 30 years. You can look up what sort of feeding they might like.