Even after Zyra's Update her Vine lashers will still be terrible.

Rylai's is one of Zyra's favorite items now and most likely in the future, because of that her thorn spitters will completely outclass her vine lashers. If you want people to use those plants you need to do 1 of 2 things, Make the vine lashers apply the grounded debuff for .25 seconds every time you get hit by them. Or make them do more damage than thorn spitters.