1:1 or 20:1: What Divides Two CBD Seed Packs
Put two packs of CBD seeds next to each other, one labelled 1:1 and the other 20:1, and they look identical: the same brand packaging, the same seed count, contents that no eye can tell apart. Grow them in the same tent and they go their separate ways from the very first step and never meet again. The reason is a single gene, and the easiest way to understand what it does is to track the two packs along each step both go through: the cross that made them, the seed, the seedling, the flowering room, the harvest, the jar, the lab report and the border. The ratios quoted as examples throughout are drawn from the range at https://calmcbdseeds.com, and that range goes 1:1, 2:1 and 20:1 with a highest line at about 30 to one; the biology is the same regardless of which shop the seeds come from.
Before the Seed Exists
Cannabis settles whether it will produce THC or CBD at one locus on the genome. The gene there exists in two versions: one builds the enzyme that turns the common starting molecule into THCA, the other the enzyme that converts it into CBDA. Every plant holds two copies, one inherited from either parent, and the combination fixes the chemotype. Two THC copies make a THC-dominant plant. Two CBD copies give a CBD-dominant one. One of each makes a balanced plant, because the two versions are codominant and not one of them silences the other.
The 1:1 pack was bred by pairing two balanced plants, each holding one copy of each version. The CBD-dominant pack was bred by crossing two plants that each hold two CBD copies and not a single THC copy between them. That one difference at the cross determines all that follows afterwards, and it is already in the seed long before it is packed.
Stage Two: Inside the Seed
Cross two balanced plants and the offspring sort themselves by the simplest arithmetic in genetics: a quarter get two THC copies, a quarter inherit two CBD copies, half get one of each. In a pack of 10 seeds that works out to, on average, two or three THC-dominant seeds, two or three CBD-dominant ones, and five true balanced seeds. The pack is sold by its parents, and in the case of half its contents the label is accurate; for the other half it does not. Calm CBD Seeds states the expected split on each balanced line, so the buyer sees ahead of sowing that a portion of the plants are going to depart from the stated ratio.
The CBD-dominant pack has no such split. Each seed received a CBD copy from both parents, every plant is going to be CBD-dominant, and the ratio on the foil holds to every one of them, within the ordinary differences in the amount of total cannabinoid an individual plant produces. Breeders describe these lines “breed true” for chemotype; the phrase refers to precisely this absence of surprise.
Where Nothing Shows
At this stage the two packs appear the same once more, and the resemblance lasts longer than most growers assume. Chemotype shows no mark on a seedling. Leaf shape, colour, stem spacing and the speed of growth are controlled by other genes entirely, and the three kinds of plant in the 1:1 pack grow without any visible difference beside one another and from each plant in the CBD-dominant pack.
One real difference during this stage comes from ancestry not chemotype. Strains with recent hemp ancestry, which covers a number of less developed CBD-dominant strains, are inclined to stretch taller and fill out less. A well-worked 20:1 strain grows like a normal modern hybrid; a young one still shows the field in its shape. Neither tendency tells anything about the ratio to come.
When the Resin Comes In
In flower the two packs begin to offer hints, and most of them mislead. Trichome density is the usual thing a grower reads, and it used to be a reasonable guide: early CBD-dominant strains carried markedly less resin than their THC counterparts, a inheritance from hemp. Current selections have largely closed that gap, and a lightly frosted plant from the CBD-dominant pack may perfectly well come in exactly where the foil promised. Trichome density and chemotype are inherited on separate genes.
Smell is an even poorer guide. The terpene profile lives on still other genes, so the THC-dominant plant hiding in the 1:1 pack can smell indistinguishable to the balanced one beside it, and both can be identical to a plant from the CBD-dominant pack. People who try to separate a balanced pack by nose at week eight are guessing, which is no any better than not sorting at all.
One Place CBD Is More Forgiving
At this stage the two packs diverge in a manner that benefits the grower of the CBD-dominant pack and the CBD-dominant plants hidden in the 1:1 pack. CBDA degrades rather slowly than THCA, so a CBD-dominant plant allowed a week beyond its peak retains the bulk of its cannabinoid content, where a THC-dominant one in the same conditions has by then begun shedding THC to CBN. The usual trichome rules nonetheless holds; it holds because the terpenes, which fade on every plant regardless the chemotype, and a late, rushed CBD flower tastes of little whatever the lab number says.
Why Each Plant Gets Its Own Label
The CBD-dominant pack can go into one jar. Every plant from it holds about the same ratio, and mixing them alters nothing worth notice. The 1:1 pack should never be handled the same way. Pool its 10 plants into a single jar and the contents is a mixture that nobody’s foil ever predicted, weighted by which plants yielded most, and nothing on a subsequent test can pull apart the plants that went in.
The discipline that saves the grief is dull: harvest the balanced pack plant by plant, dry each apart, label each, and test them one at a time before the crop is mixed. This is the only point in the entire grow at which the different chemotypes of plant in the 1:1 pack can still be told apart short of a laboratory, and then only because each is at that moment in its own bag.
Reading the Two Results
Send a few grams from every jar to a laboratory and the two packs finally are legible. For the CBD-dominant pack the certificates come back clustered closely around the stated ratio, differing mainly in total output rather than in balance. For the 1:1 pack they come back in three groups: some reports with nearly all THC, some showing almost all CBD, and the rest somewhere near one to one. Nothing of this pattern is a failure; it is the breeder’s cross expressed as numbers.
Over-the-counter test kits are sold for growers who cannot reach a laboratory, and most show whether THC is there rather than how much. That is enough to pull the THC-dominant plants away from a balanced pack and insufficient to assign a ratio to the rest, which matches the commonest use: finding out what of the 10 jars is going to catch out a guest.
Hemp Threshold Versus Chemotype
The last stage at which the two packs diverge is legal, and it trips growers who thought “CBD” meant “hemp”. The majority of countries classify hemp by a THC limit, a fraction of a percent of dry weight, with the exact figure varying by country and sometimes year to year. A plant from the CBD-dominant pack making twenty percent CBD at twenty to one also makes about one percent THC, which is several times above most limits. Certified hemp cultivars are selected to hold total cannabinoid output down so the THC fraction remains below the line at maturity; CBD flower lines are bred for rich content and allow the THC rise with it. A seller that offers only a ratio is selling a flower line; a grower who needs a compliant crop needs to look for a tested THC percentage at maturity and order no line that cannot provide one.
Past the threshold question, the chemotype changes very little in the law on the seed itself. Where owning cannabis seeds is permitted and germinating them is not, the 1:1 pack and the CBD-dominant pack fall under the same position as every other pack. Where the plant is permitted outright, the choice between them is the grower’s and nothing else’s. None of this page is legal advice, and the rule which counts is the one where the seed will be sown, rather than the one in the place it was bought.