Soil & compost
How much potting soil does my pot need?
Pot volume in dry quarts, which is how potting mix is actually sold. A 12-inch pot takes roughly 8 dry quarts.
How this works
Potting mix sells in DRY quarts — 1 cu ft is about 25.7 of them. Round pots taper toward the base, so the math takes 17% off the straight cylinder.
Questions people ask
How many quarts of potting soil for a 5-gallon bucket?
About 15 dry quarts. Potting mix is sold by dry volume and a 5-gallon bucket is a liquid measure, which is why the numbers never line up.
Can I reuse last year's potting soil?
Yes, for most things. Refresh it with a third fresh compost and a slow-release feed. Do not reuse mix from a plant that died of root disease.
Is garden soil the same as potting soil?
No. Garden soil compacts in a container and drains badly. Potting mix is mostly bark, coir or peat plus perlite, and holds air after watering.