Easy calculation

[abulton]

If length and width of you garden is a and b respectively. Then area will be
area=a*b
But keep in mind that, volume=length*width*height
So your garden have no volume.

[robertR0931]

I am not understanding what your question is here. You garden will not have volume because volume is not the same; although once you actually have items in the garden you do indeed have a number that you can translate into volume because you have a quantative number.