How much Soil do I need?

Star-Tip 1026

Gardening Tips for successful and beautiful Landscapes and Gardens

How many times have you wondered about the amount of potting soil you need to fill a flower pot? How about a raised Flower bed?

This should help:

Pot Diameter in INCHES.....Soil needed in QUARTS and C.F. (cubic feet):
1 US quart = 0.033420139 cubic foot (divide quarts by 30 to get c.f.)

These are “typical” pot volumes, and some designs may vary considerably.

3.5”….. ~ 0.007 c.f. = 11.5 c.i.

4.0”….. ~ 0.016 c.f. = 26.8 c.i

6.0”….. ~ 0.042 c.f. = 72.5 c.i

8".........3 QT = 0.10 c.f.
10".......5 QT = 0.17 c.f.
12".....12 QT = 0.41 c.f.
14".....18 QT = 0.61 c.f.
16".....22 QT = 0.74 c.f.
20".....28 QT = 0.94 c.f.
24".....36 QT = 1.21 c.f.
30".....72 QT = 2.41 c.f.
36".....96 QT = 3.21 c.f.

Window Boxes
6' x 6"x 6".....3 cubic feet
4' x 6" x 6"....1 1/2 cubic feet

every 2' of (6” x 6”) additional window box: add 1 cubic foot of potting soil

Raised Beds:

1) Determine the dimensions (in inches) in the bed that are square or rectangular (exclude rounded ends). Multiply length x width x depth.

2) Measure (inches) the inside width (diameter) of one of the 2 rounded ends. Multiply 3.2 x width x depth.

3) Add results from (1) to (2) and divide by 1,728 and you’ll have the cubic foot requirement for the soil mix to put into the beds,