Hari planted 324 plants in such a way that there were as many rows of plants as there were number of

Hari planted 324 plants in such a way that there were as many rows of plants as there were number of columns. Find the number of rows and columns.

Let r be the number of rows and c be the number of columns. We have the area:
rc = 324

Since rows equal columns, we have a square, and we can set r = c.
c^2 = 324

Take the square root of each side:
c = 18

Which means r = 18 as well.

What we have is a garden of 18 x 18.