BCSS - Forum

I was just looking at the monthly temperatures in Sucre, Bolivia where these plants grow and it rarely goes above 20-25 deg.C during the summer. Night time temperatures are lower alright.
So I don't think upping the day time temperature over 25 deg.C is going to help me.

I think the problem is that the plants are self-sterile and fertile seed is rare.

I also get a lot of variation in the seedlings. So much so that I suspect bouncing bombs and/or other mistakes along the way.
Here are some photos from 2022. Whatever about trays 10A and 10B, 10C certainly looks suspect.

ST22-10A Sulcorebutia augustinii jakubecii LH 1723
ST22-10B Sulcorebutia azurduy LH 1422
ST22-10C Sulcorebutia bicolorispina KK 809

Hi
These seedlings (S. heinzii RH_3237) are a little more variable than average. They are all from the same sowing.

In terms of temperature, I've recently been growing Sulcorebutia crispata subs. hertusii from seed and they come from around Zudañez which
looks to get up to 27oC or so. So lower mid 20's seems a good temperature to go for?

From my 'extensive' research on the subject over the last week or so, there's a couple of pointers that might help germinate troublesome Sulcorebutias.

The European growers tend to sow the seeds at the end of April and start of May with no additional heat.
So you'd expect fluctuating night/day temperatures may help.
Also plenty of light, but of course not direct sunlight.

Also upping my seed count may be a help. I'll try this no-brainer next sowing.
The cost of another 10 seeds compared to the time and effort that goes into the whole seed raising session may be well worth the few extra bob.
10 seeds isn't much truth be told.

SimonT wrote: ↑Wed Nov 29, 2023 1:09 am Hi
These seedlings (S. heinzii RH_3237) are a little more variable than average. They are all from the same sowing.

In terms of temperature, I've recently been growing Sulcorebutia crispata subs. hertusii from seed and they come from around Zudañez which
looks to get up to 27oC or so. So lower mid 20's seems a good temperature to go for?

Presumably these are air temperatures in the shade.
If warmed by sun, soil surface temperatures can be MUCH higher. Upping to daytime maxima of 35C or higher could be worth a try.

esp wrote: ↑Thu Nov 30, 2023 3:14 pm

SimonT wrote: ↑Wed Nov 29, 2023 1:09 am Hi
These seedlings (S. heinzii RH_3237) are a little more variable than average. They are all from the same sowing.

In terms of temperature, I've recently been growing Sulcorebutia crispata subs. hertusii from seed and they come from around Zudañez which
looks to get up to 27oC or so. So lower mid 20's seems a good temperature to go for?

Presumably these are air temperatures in the shade.
If warmed by sun, soil surface temperatures can be MUCH higher. Upping to daytime maxima of 35C or higher could be worth a try.

This echoes what Nobby (Norbert Sarnes) has written in another thread about the environment in which Austrocactus grow and he recommends starting with a daytime temp in mid 20s but then rising to mid 30s after a couple of weeks. Combined with night temps a few degrees lower this works well for Austrocactus for me. It has been a while since I sowed Sulcos but I will use this regime if I do so again.

The numbers I was quoting were air temperature. There is some warming from underneath for my pots and also sunny winter days
push the air temperature up a bit, so the compost can get a bit warmer. I did think of getting a soil temperature probe but even then it is really the
temperature that the seeds sense that is important and they are on the surface of the compost. In terms of air temperature my seed area gets a max of 30ish and a minimum nightime of 16-18oC but most of the time is mid 20oC.

I had an experience a few years ago when germination was modest, my seed tray got warmed quite a bit in the sun on a hot day and after that a lot of new germination started. I'm always trying to repeat this accident!

I contacted a few of the seed suppliers and as ye know those lads don't have time to answer random questions, but a couple did get back to me.

They sow their seeds at the end of April, or beginning of May in the greenhouse with no additional heat.
With the subtext, "They either come up or they don't".

So I think I'll do my usual in mid-March and turn off the heat at the end of April.
It might help.....

Hi
I really like growing over the winter indoors.
If the seeds sown in the winter fail to germinate then at least there is plenty of time to try again!

Would it be foolhardy to re-bag a pot again this Spring? A pot that has been exposed and dried out over winter.
Some of my seedlings are very small and I don't think they will survive.

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.....

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?