How to Read a Cannabis Seed Spec Sheet
A cannabis seed spec sheet is the table of recorded figures a seed bank publishes for a strain: cannabinoid content, flowering time, yield, height, lineage, terpenes and effect. On this site that table sits on every strain page under the name Plants Don’t Lie, it has the same nine rows every time, and this guide explains what each row records and what it does not.
Most of the confusion in this category is not caused by sellers publishing wrong numbers. It is caused by different sellers measuring different things and printing them under the same label. A flowering time of nine weeks and a flowering time of thirteen weeks can both be true for the same plant if one is counting the flowering stage and the other is counting the whole run from seed.
What is on a TAG spec sheet?
Nine rows, in the same order, on every strain page. A row is never dropped and never filled with a dash, a zero or a guess. The table is on every listing, for example Bramble Jam, Irnglu32 FruitiBlicious and FruitBglu32.
| Row | What it records | Format used here |
|---|---|---|
| THC | Tetrahydrocannabinol as a percentage of dry flower weight, from a tested sample | A single figure, for example 18.4% |
| CBD | Cannabidiol, measured on the same basis | A single figure, for example 0.4% |
| Flowering time | The length of the flowering stage only, not the whole run from seed | A number of days, for example 63 |
| Yield (indoor) | Dry flower recorded per square metre of canopy indoors | Grams per square metre |
| Yield (outdoor) | Dry flower recorded per plant outdoors | Grams per plant |
| Height | The finished height the line was recorded reaching | Centimetres, usually as a range |
| Lineage | The two parent plants the line came from | Mother name x Father name |
| Terpenes | The aroma compounds identified in the tested sample | A short list, most prominent first |
| Effect | How the people who tested the line described it | A short phrase |
What does flowering time actually mean?
On this site, flowering time is the length of the flowering stage on its own. It starts when the plant shows its first flowers and ends when the line was recorded as finished. It does not include the growth stage before that.
This matters because seed banks split roughly two ways on it and rarely say which side they are on. The whole run from seed is the longer number, and for an autoflower the growth stage before flowering commonly adds another three to five weeks on top of the flowering figure. Comparing a flowering time from one seller with a seed-to-harvest time from another is the single most common way a line’s real timeline gets misjudged.
If a listing anywhere does not state which of the two it means, treat the number as unusable rather than as a fact. The difference between the two is explained further in Autoflower vs Photoperiod Seeds.
Why are indoor and outdoor yield listed separately?
Because they are measured in different units and are not interchangeable. Indoor yield is recorded in grams per square metre of canopy, which describes an area of plants rather than one plant. Outdoor yield is recorded in grams per plant, because outdoors a single plant has as much room as it wants and a square metre figure would mean nothing.
Putting them in the same row, or converting one into the other, would produce a number that was never measured. They stay as two rows.
What do the THC and CBD figures tell you?
They give the percentage of that cannabinoid by weight in dry flower from a tested sample of that line. That is all they give.
They are not a statement about strength as experienced, they are not comparable across testing labs without care, and they carry no medical meaning of any kind. A figure recorded on one run under one set of conditions is evidence about the genetics, not a guarantee about any other run. Where a range is published rather than a single figure, the range is the honest form and a single number picked out of it is not.
Why do some rows say “Data pending grow-test verification”?
Because that line has not been grow-tested by TAG yet, and the alternative is to make something up.
Every seed bank knows what a plausible number looks like for a given strain, which is exactly why so many published specs are plausible and wrong. TAG’s rule is that a spec row is filled in from a recorded result or it is left marked as pending. An empty cell is information: it tells you the difference between what has been measured and what has not, which no rounded-up estimate can tell you. A line listed before its grow-test is finished carries pending rows until the figures exist, and they are filled in when they do.
This is what Plants Don’t Lie means in practice. It is a rule about what gets published, not a slogan about quality.
What a spec sheet is not
It is not a promise. The figures describe what a genetic line has been recorded as doing, under conditions that were not yours, and no seed bank can commit to a result in someone else’s space.
It is also not an instruction. Cannabis seeds are sold on this site as collectible souvenirs, germinating them is illegal in the UK, and the spec table exists so that a collector can tell one line from another and understand what they are holding.
Frequently asked questions
Why do different websites give different flowering times for the same strain?
Usually because they are measuring different things: the flowering stage against the whole run from seed. Some of the difference is also genuine variation between growing conditions and between individual plants from the same seed line. A figure with no stated basis is not comparable with anything.
Is a higher THC percentage a better seed?
It is one recorded property of one line, nothing more. Terpene profile, structure, flowering length, resilience and the honesty of the seller all sit outside that number, and the number itself is only worth as much as the testing behind it.
What does the lineage row mean?
It names the two parent plants the line was bred from, written as mother by father. Lineage is the most useful row for placing an unfamiliar strain, because the parents are usually known quantities and the offspring tend to sit somewhere between them.
Do all TAG strains have a complete spec table?
Not yet. Lines that have been through a full grow-test carry complete figures, and lines that have not carry pending rows until they do. Browsing the seed shop shows which is which. For how the seed types themselves differ, see What Is a Photoperiod-Derived Auto?.