@cold52
I like it, although the text is currently a little messy. I think this is what your getting at:
Thistle
Grow: +1/+1
At the end of your turn this card gets -1/-1 and a sprout is spawned in a random nearby square.
Sprout
Grow: +1/+1.
If this minion has at least 2 attack, and 3 health it gains: At the end of your turn this card gets -1/-1 and a sprout is spawned in a random nearby square.
Pretty neat, although my suggestion is to make it a little more simple. Remove the grow and the -1/-1 from thistle and just make it spawn a sprout at the end of turn.
Make sprout just a simple transform into a thistle. Currently you have some very weird mechanics that may be hard to put in the game.
As a backline minion It seems a bit slow, I think the thistle should be a bit more beefy so it’s good on the frontline.
My suggestion:
Thistle
4 mana (3/5)
At the end of your turn summon a sprout on a random nearby square.
Sprout
0/1
Grow: +1/+1
If this card has at least 2 attack transform it into a thistle at the end of your turn.