I have some batches of seeds that didn’t germinate this spring and put them back in the fridge when the temps started rising to 25°c a couple months ago. My plan was to take them out this fall and give them another chance then.
Several of these batches have now started to germinate in the fridge. Usually I’m thrilled to see any germination, but this is terrible timing. Temps this week have reached 35°c, and of course it’s only going to get hotter in the coming weeks (last summer we maxed out at a sweltering 46°c in July).
I took one seedling out this weekend after the cotyledons opened in the fridge, and put it into a small pot in my usual indoor area, but it wilted and died within a day. I don’t use a/c during the day when I’m not home, and I think the shock of going from the fridge to the heat was too much.
I guess I could put them in a shaded area outside, against a north facing wall? I’m wondering if I should use an icepack in the water tray, like the opposite of a heatmat? Or just let them fend for themselves and see what survives?
Does anyone have any recommendations for handling these midsummer germinations?
No experience with heat based issue except opposite - put seedlings out of warm damp trays to harden for late spring in cool - cold garage … they went south quick - shrivelled and desiccated.
Would micro O/H water misting (spray) system as used in outside patio restaurants be practical for your logistics trays and wall/ roof?
Never really gets hot here except for maybe 7-10 days a year (33-35C).
I don’t have any experience with it either, but I expect drying could be a significant part of the problem
At the cotyledon stage, I don’t expect the very limited root system these seedlings have to be able to sustain a water intake sufficient to keep up with the transpiration you experience with high temperatures
I wonder if putting these seedlings in a plastic bag until they grow enough roots to sustain the heat could prove to be useful, much like what you would to with cuttings. I can’t guarantee that it will work, but it’s something I would try
I agree, initial humidity is key for seedlings that have already gotten too large inside the refrigerator. If you pot them up before they reach that stage, they are usually fine; with care they can usually be okay even beyond that point, unless there has already been some decomposition. I try to catch seedlings and pot them up before the cotyledons open, and usually well before that. If they have gotten a little past the ideal point, a clear cover or bag of some kind helps to stabilize them until they green up, and can be gradually lifted or opened over a couple of days to harden the seedlings to ambient humidity.
Stefan
Thank you all for these replies!
Ambient humidity here this morning is 85% outdoors, projected to drop to 60ish during the day.
@RikuHelin , the misting system is impractical for the time being, but it’s something I have been looking into for cuttings. I’ve been looking at vivarium/terrarium supplies, there are pretty decent climate control options including misters and evaporative coolers that I could install in a countertop sized tank. Looks like my next project is shaping up!
@jAc123 I’ll give the plastic baggies a try , thanks!
@MidAtlas It’s unfortunate they got to this stage in the fridge. I wasn’t even checking for germination at this point and it really took me by surprise when I saw green! Some still haven’t broken out of their seeds completely, hopefully they will fare better.
I have potted them up and put them against the north facing wall on the roof. I will cover them with plastic baggies during the day and let them breathe at night when humidity is highest.
Good luck, hard enough sometimes to get prized germinations so go for the save…
… and mister project should be an interesting project to determine if needed and commercial products practical for your needs.
… about a generation ago l went “full rube goldberg” on a recycling (water) self contained home made mister system (aquariums sump pump timers tubing nozzles etc etc) … suffice to say l never went rev 2.0 and have lots of odds and ends kicking about, nozzles tubing and red green duct tape.
Fun and it worked just decided not a critical need and hand sprayer adequate and indoor real estate needed for vintage storage.