How long will the flower at Furano stay ?

I have a plan to visit Hokkaido 28/7-2/8 this year. My itinerary is Hakodate (28-29/7) - otaru (30/7) - furano, Biei (31/7) and others day in Sapporo. So I can use JR pass for the first 3 days and then drive a car in Furano and Biei.
But I'm not sure is it too late to visit Furano and Biei at 31/8/58 ? Or I have to change my plan to visit Furano since my first day (28/8/58)?

Regards,
Thank you in advance

Hi,

I visited Furano and Biei last year in the middle of August.
You can see photos of the flowers here:
http://zoomingjapan.com/travel/hokkaido-in-summer/

It was beautiful!
Only the lavendar was not blooming anymore.

Thank you so much for your share, I really appreciate this !!