The most common and most likely answer to this crossword clue is the 5 plus 3 plus 6 letter word LORDS AND LADIES
L
O
R
D
S
A
N
D
L
A
D
I
E
S
More clues leading to the result LORDS AND LADIES
Buddy explains!

The straight part
We know that "plant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case plant = lords and ladies.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.