>> never heard of Holland Greens.
I didn't find them in many places! I bet a lot of people are turned off by "stubble turnips" and "cover crop", but when I heard "very very mild", I thought I might like them better than some greens where the seed vendor said the mustard taste was not all THAT strong. I've learned that that means "yes it IS that string".
I missed planting much of anything last year, but I have high hopes for 'Tyfon' / Holland Greens this year.
Right now I'm far behind on sending things to people who are expecting them, but if you don't find them at your usual seed sources, remind me to send you some. I got the "one ounce for $4.35" back when it was only $3.95.