Some seed will not germinate straight from the packet
Some seed will not germinate straight from the packet. It carries a built-in dormancy that a pre-sow treatment has to break first. A hard-coated seed is scarified or soaked so water can get in; a seed with internal dormancy is cold-moist stratified (chilled damp for weeks) before it will come up. The treatment has to be started far enough ahead of the sowing date to finish in time.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
A hard, water-impermeable seed coat holds the seed dormant by blocking imbibition, so nicking, abrading, or soaking the coat is what lets water reach the embryo; a seed with physiological dormancy stays shut until a period of cold, moist chilling lets its germination-inhibiting hormones dissipate. So each treatment takes its own span of time, and starting it late leaves the seed still dormant at sowing.
What to do about it
Check the plant's page for the treatment it needs. Scarifying (nick, abrade, or a hot-water/acid treatment) and soaking are done right before sowing; cold-moist stratification takes weeks, so start it well ahead. About six weeks before the intended sowing date is a safe general lead, though the exact period is species-specific and is on each plant's page. Fall-sowing outdoors lets winter do the chilling for hardy natives.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Seeds might have a hard or thick seed coat (physical dormancy). This can be broken by soaking or scarifying (scratching the surface) the seed
A tough seed coat prevents water uptake and seed germination
Read next
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Sources updated
- Wording made clearer
- Added to the rules
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Milpa Gardens. “Some seed will not germinate straight from the packet. It carries a built-in dormancy that a pre-sow treatment has to break first. A hard-coated seed is scarified or soaked so water can get in; a seed with internal dormancy is cold-moist stratified (chilled damp for weeks) before it will come up. The treatment has to be started far enough ahead of the sowing date to finish in time.” Evidence grade: Promising. https://milpa.garden/rules/some-seed-will-not-germinate-straight-from/
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How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.