Sulcorebutia crispata seed germination

[habanerocat]

Have you watered the pot now?
I find seedlings can take ages to recover from rest. Once they start growing can't you just give them a bit more water
than for more established plants?

No, I haven't watered yet.

But you're right, their only hope is water.
These are fully developed seedlings, if you know what I mean.
They are just tiny.

[habanerocat]

What's the lowest temperature you'd dare let your newly planted seeds drop to at night?

I've turned off night time heating but there's frost due this weekend.

[SimonT]

I let the temperature drop ~10oC at night, so it goes much lower than 15oC at night.
I have my seedlings indoors so this is relatively easy to achieve.

[habanerocat]

I let the temperature drop ~10oC at night, so it goes much lower than 15oC at night.
I have my seedlings indoors so this is relatively easy to achieve.

Thanks, I read that first as -10C on my phone but now on the PC I see you mean 10C approximately.
Looks like a min of 10C would be good alright.
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I'll crank up the main heater to compensate or else just go back to manual settings.
I've probably started them too early in the year as I intended to remove all heat at night.

[habanerocat]

On the temperature swings mentioned above.
I've modified my electrics to take this into account and we'll see how it goes this year.

Hopefully I'll return here to note an improvement.....

I've just opened my seed bags over the last few days and as promised I've done some more Excel wizardry to analyse how I got on this year.
Having a day/night temperature swing does seem to help rather than a constant 21Deg.C.
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Results.jpg (15.87 KiB) Viewed 153 times

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These are just average figures with of course some seeds doing very well and some not germinating at all.
From a hobbyist point of view my sample sizes were fairly large.

To clarify I remover night time heat in 2024 and held day time heat at about 21Deg.C.
Also in 2023 I used three layers of cling film, whereas in 2024 I returned to freezer bags.
I found in the summer of of 2023 the pots were drying out, to such an extent that I was injecting water in past the cling film.
If anything my pots in 2024 were too wet, possibly resulting in some damping off. Something I had never experienced previously.

I used three seed suppliers both years and had hoped to recommend a crispata that germinates well, but unfortunately I can't.
LAU390 gave me almost 100% germination in 2023 from one supplier, but was a let down the following year from others.

JO637, HS256 & VJ110 seemed to be best while I couldn't get any of KK1266 & KK1267 to germinate at all.

[SimonT]

It is good that you see an improvement with the new conditions. When there is a lot of variability between batches
you need a lot of seed sowings just to work out any sort of trend. I'm planning to try extra washing of my seeds this year in an attempt to
remove fungus. I don't have a lot of problems with fungus generally in baggies but sometimes specific seed batches seem to
bring fungal spores in. I'm not sure if the seeds rot if they can't germinate or the rot stops germination. But I'm going to try to find out!