Bad germination techniques are rife among cannabis growers, especially folks working indoors.
Damping Off is a problem when germinating any species of plant indoors. But cannabis originated on the arid and windy desert steppe of Central Asia so is particularly prone to infection by Damping Off pathogens.
Damping Off diseases thrive in damp, soggy, poorly ventilated enviornments and can kill cannabis seeds before they even open. The various pathogens involved in Damping Off prefer cool environments, not warmth.
We very seldom receive complaints about germination, but when we do, two words always feature: ’tissue paper’ aka ‘paper towel’….
Often thrown in for good measure are ‘plastic bag’ and some kind of sealed plastic container like a ‘CD case’.
Others we see from time to time are ‘propagation dome’ or ‘humidity dome’.
Unsterilized, these set-ups make for really effective ways to kill cannabis seeds and seedlings. They’re boutique residences for fungal and bacterial Damping Off pathogens.
Boutique residences for Damping Off pathogens, not cannabis seedlings
Where legal, if you’d prefer to germinate – not kill – your cannabis seed:
1. Sterilize your seeds (e.g., in 3% hydrogen peroxide for 3 hours)
2. Place in new, sterile Seed Compost no deeper than the width of the seed
3. Add lots of warmth (e.g., under a grow light at +25 °C) and carefully water
4. Ensure the space is very well-ventilated
The standard Seed Compost formula for sowing any type of seed is John Innes Seed Compost. John Innes is not a brand but a range of composts developed at the John Innes Institute.
2 parts sterilized loam (9 mm sieve)
1 part peat
1 part horticultural sand
Per cubic metre add:
0.6kg ground limestone
1.2kg superphosphate
Clearly peat etc. need substituting. Here’s a peat-free formula.
Note that the loam is sterilized with steam.
See this piece from the RHS on how home-produced compost is a common cause of Damping Off.
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Sterilize seeds by soaking in very dilute hydrogen peroxide. The small amount of chloride in tap water is useful (enough of the distilled water already!).
Peroxide is antimicrobial. The point is to minimize the likelihood that fungal or bacterial pathogens on or in the seeds will cause problems such as killing seeds before they germinate or infecting seedlings. Peroxide is also said to soften seeds and accelerate germination.
Putting seed from the Southeast Asian tropics or Central Asian desert into a plastic bag stuffed with sodden, lukewarm, unsterilized tissue paper isn’t a recipe for success.
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To the diehards among the paper towel / plastic bag posse:
This technique is a gift to bacteria and fungi. It pits everything against the seeds in favour of microbes.
Seeds do not need you watching or touching them in order to germinate.
Wet tissue paper rapidly becomes a microbial soup when it and your seeds aren’t sterilized, yet more so when it’s sealed inside a ziplock bag.
Using such conditions to germinate seeds of a landrace direct from a dry Central Asian region such as northern Afghanistan is suboptimal – and that’s putting it kindly.
Real landrace seeds have not had four decades to adapt to the bad practices of indoor growers.
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Every accession that goes on our sites is tested and retested.
Nothing is listed unless above an absolute minimum of 80% germination – or it says otherwise. Most accessions should give you 100% germination or close.
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Photo shows Bokeo #2, an accession of a cannabis landrace from tropical Southeast Asia – a type once used for making ‘Thai stick’.
