Moisture Medium for Extended Warm Stratification

[ThirdCoastBorn]

Hard to believe, but I need to start preparing next year's batch of seeds -- am limiting myself to just a few species (haha) and have already received the ones that need warm stratification (two for 3-4 months, one for 6-17!) . This past year, several of my trays got moldy while in the fridge, happened to seeds in bagged starter mix (Hoffmans) and also ones in layered perlite. So as someone who's obviously prone to overwatering, I'm a little dubious of going with milled sphagnum as FW Schumacher suggests (anti-fungal properties)

I'm inclined to try perlite:vermiculite that's sprayed with fungicide, but am unclear as to what type/brand works best; have tried peroxide before but perhaps not at strong enough concentrations, also have liquid copper on hand. I may do the warm stratification outside, but will have to use the fridge as our winters aren't reliably cold/long enough.

Any suggestions are most welcome! Thank you.

 

[ThirdCoastBorn]

Forgot to mention that I also tried stratifying via paper towels, same moldy result -- still got a few of them to sprout but assume there would've been more. I even tried to be cognizant of "wet vs. moist". Maybe it's the fridge

 

[0soyoung]

I like to use paper toweling moistened with a hydrogen peroxide solution (2 tablespoons 3% peroxide from the grocery/pharmacy in a quart of water). I fold a half-sheet towel once lengthwise and then crosswise. I put the seeds on a smaller piece of plastic, which is folded over the seeds and put in the folded damp towel' packet (the plastic keeps the seeds from getting all snarled up in the damp paper). I put stacks of these packets into a gallon size ziploc bag. Redampen with the peroxide solution as needed.

The peroxide solution is antiseptic, nixing both bacteria and fungi, and seems to also take care of the mildew that will inevitably appear on the paper.

 

[Shibui]

Treating after assembly is sensible. Putting dirty seeds crawling with spores into clean media does not make much sense quite apart from handling it all with hands crawling with all sorts of bacteria, etc. Most people are very surprised at what is actually on our skin. Most fridges are also a haven for micro bugs. Sealed plastic bags should keep them on the outside though.
If the whole thing starts clean it should stay clean so clean hands properly before handling anything then treat both seeds and media. New plastic bags should be reasonable free but if reusing anything treat it too.

The problem is probably not overwatering, rather contamination.

 

[Wires_Guy_wires]

The microbes on our skin don't like wet and cold, so contamination issues from handling are unlikely. Bread and vegetables handled in the same kitchen however are a different story.

Aeration is key. I sometimes use plastic cups meant for growing fungal cultures; they have air filtered lids. Nothing gets in or out except air.

One thing to remember is that paper towels are highly processed compared to regular paper, so it's way easier for fungi to take hold. Newspaper for instance doesn't get moldy after a few weeks while paper towels do. For my fungal cultures I prefer using cardboard because it doesn't need sterilisation very often to stay clean long enough for a culture to take hold. It's hard to contaminate cardboard with trichoderma for instance.

Combine these and you'll probably be good to go.

 

[leatherback]

Lts of intersting advice. I am just wondering.. WHat do you have that needs a year of warm stratification?

 

[ThirdCoastBorn]

Hi everyone,

Very sorry for dropping the ball on this thread (had problems accessing the site after the update) -- I want to thank you all for your helpful comments & advice. Hygiene is DEFINITELY something I need to be more mindful of (especially as I gear up for cuttings!); the kitchen being a terrible prep room never crossed my mind but makes total sense.

This past season, I mostly used 12-cell trays from Amazon with a covered humidity lid, which I would vent once or twice a day for a few minutes until seeds began germinating (after any pretreatment). During an extended warm stratification, how important is regular airflow vs. consistent humidity? Would venting ~weekly when I check moisture be sufficient or should I poke a few holes in the lids? Hesitant to leave them off completely...

I'll certainly be trying zip-locs with newspapers, interesting note about processed paper towels. Would unbleached/natural coffee filters be another good choice?

Rusty Blackhaw Viburnum -- I assume it's doubtful as bonsai, but I've recently started selling extra seedlings to a native plant nursery and it's (apparently) their most requested species because of its difficulty/rarity. So that and it gives me an excuse to play with GA-3

 

[cmeg1]

Put some orchid spahgnum in there too....I never see mold when I use orchid spahgnum in cold stratification......zero mold