From what I remember last year, my 'Mars' did lose some or most of its purple coloration during the summer - whether it was the shade it was growing in, or if it simply turns green every summer, I'm not certain. It proved tender in a zone 4 Minnesota winter and I lost the plant, so I can't say much more.

Stefan

Mine is loosing the purple coloration too :-)But it's because I had to cute the leaves: red spiders :-( The new ones are small and green. It's the first year I have it (thx Nath') so can say more except it does not make blooms, not seeds too (I had plenty of begining of flowers, but none make a bloom). Anyway, summer is not a good time for violet. Hope it won't die during winter :-( Crossed fingers and protection.
Mars is a good plant for imagination or fun, leaves are definitively crazy but that's all. What is the interest to have a violet which doesn't make any bloom and which is sterile ?

I bought it before I knew much about it, I just liked the purple on the leaves. I was a little dissapointed that it never bloomed. Hopefully the purple will fill in. I have had mine for 3 years now. It's possible that it lost some of it's coloration before and I just didn't notice. Thanks. -Ais.

FYI: Viola 'Mars' is a Japanese hybrid V. hirtipes f. rhodovenia x V. japonica, introduced by Terra Nova Nurseries in 1998. The leaf-colouration comes from the f. rhodovenia side of the cross (you can work out what that Latin means).