Elsgeesterweg off to the right of that route goes through a load of flower fields too - we stopped at the Euro amp there a few Easters ago and the riding was great.
[edit] I was of course zoomed in...... basically the road between Voorhout and Rijnsburg that goes past Koningshof
https://ridewithgps.com/routes/29521608
Used to ride this route nearly every month, but did some editing to get you into the flowers.