Walk down any garden-center aisle and you will see a wall of bags with the word castings on them. Some of those bags have been sitting under warehouse lights for a long time. So how do you tell fresh worm castings from an old dry bag? On our farm in Seymour, Missouri, we use something we call the porch test. It takes about a minute, and you do not need a lab.
Why fresh worm castings are different
Fresh worm castings still carry a living community of tiny microbes when they leave the farm. That is what we mean by FRESH: alive when it leaves us. A bag that has dried out on a shelf for months can still be organic matter that fluffs up a potting mix. What is often missing is the lively part. We think of fresh worm castings as a starter culture, not dust.
The porch test, step one: smell
Open the bag and take a sniff. Living worm castings usually smell like a clean forest floor after rain. Earthy and pleasant. If it smells dusty, musty or like nothing at all, the biology may have gone quiet. If it smells sour or rotten, that is a different problem, and we would not put it on your favorite plants.
Step two: feel
Pinch a little between your fingers. Fresh worm castings feel crumbly, soft and a little moist, like good garden soil. They hold together lightly and then fall apart. An old dry bag often feels like powder, or like hard little pellets that have been crushed flat. Neither one hurts anything, but it is not the same thing.
Step three: story
Ask where the castings came from and how long they have been sitting. A good seller can tell you. Ours come from our own worms on our Missouri farm. Orders close on Tuesday, and we pack and ship on Friday, so your castings spend their time with the worms, not in a warehouse.
What the porch test is not
The porch test is a look-and-feel check. It is not a lab report, and we do not name or knock any other brand. Dry bags can still have a place in a potting mix. We just want you to know what you are buying, so you can pick what fits your plants and your shelf.
How to keep fresh worm castings fresh at home
Keep the bag out of direct sun and away from heaters.