How to Tell If Weed Is Stale or Bad

Stale weed and bad weed are different problems. Stale flower has lost its smell and dried out. Bad flower has something wrong with it, mold being the main one, and should not be used. This page separates the two and says where the evidence ends.

Stale

In the storage study the average terpenoid concentration decreased by more than 50% at t4(flower storage study).

Terpenoids are the aroma compounds, and that measurement came from one CBD-rich variety. A faded smell is still what you would expect from older flower. Other plain signs, from our own handling experience and not from a study:

The smell is faint or flat, or smells like hay.
The flower crumbles to dust when you touch it, instead of springing back.
The package date on the label is old.

Stale is a quality call, and you are the judge. The label shows the date the package was filled and a batch number, so you can read the age of what you hold.

Bad

Marijuana must be tested for contaminants including mold and mildew(CMR testing rule).

A test covers the sample on the day it was taken, and storage afterward is a separate matter. We found no regulator or study that publishes a visual checklist for mold on cannabis, so the signs below are plain observations and not a standard:

A musty or damp smell, like a basement, instead of a plant smell.
White, gray or green fuzz or powder on the flower or on the paper of a pre-roll.
Flower that feels damp or sticks together in clumps when it should not.
Any visible spot you cannot explain.

If you see or smell any of these, do not use it. Do not cut off a spot and use the rest, because you cannot see how far mold has spread through the material.

What to do

Take the package back to the store with the label. Ask about the batch number.
Look up the batch's certificate of analysis. AC publishes the lab report for one tested batch of each strain that has one, in its COA library.
Buy fresher flower next time and store it as described on the storage page.

Short answers

How can you tell if weed is bad?

Look for a musty or damp smell, and white, gray or green fuzz or powder on the flower. If you see or smell either, do not use it. No regulator publishes a visual checklist, so these are plain observations, not a standard.

How do I know how old my weed is?

Read the package date on the label. The batch number leads to the lab report.

Is dry weed bad weed?

Dry flower that crumbles is stale. Mold shows as a musty smell, or fuzz or powder on the flower. Dryness alone is not a sign of mold.