Yes, there is no evidence to believe they are “conscious” (well, not exactly sure what is meant by conscious here since that word is closely related to religious beliefs in many cases, but assuming it means sentient), they lack all known biological features that could possibly lead to sentience, and there has been no evidence found so far to suggest there is any sentience among plants.

Also, considering they’re rooted to the ground and cannot move there is no evolutionary advantage to sentience (and actually there are massive disadvantages since it will use energy for sentience which serves no purpose). Now, just because there isn’t an evolutionary advantage, or even if it’s an evolutionary disadvantage to a property doesn’t automatically mean it doesn’t exist, but given that there’s no other reason to believe it does exist this is just another piece of the puzzle that shows it doesn’t even need to exist.