Even you attack the mini plants, it will come back again and again, what you will do is use the sprout-o-matic,then plant it on a sands and when you attack it with your wrench,it will have a effect.

if you are talking about the red carnivourous plants, use the following weapons:
RYNO,lacerator,electro rockets,acid bomb gloves,agents of dread and etc.

I just used the Acid Bomg Glove.
That's how I p***ed it.

use a gun

iron lombax, on 2nd planet! not have all them guns

USE A WEAPON1!!1!11!!!11!1
you just have to hit the plant!
XD