CactiGuide.com

Really happy looking seedlings.

Thank you!

I have one question for anyone. I currently have the light on for 16 hours a day. Would it make any difference if I increased it to 17 or 18? Or should I do it with time?
I found different information about this, some say 14 hours is the best, but others say 18.
Starting with it that it's not too much, would it bring any benefits at this age?

Cacti use CAM photosynthesis, their stomata open to let in CO2 at night - they need the dark time to breathe! Too long a light period could actually suppress growth, as the plants would be unable to take in enough CO2. As you found, there are differing opinions about what the maximum period of daily light is. Likely the optimum varies with different species - those that grow in the higher latitudes, where the days are much longer in the summer, are undoubtedly adapted to thrive with longer days. L. williamsii is not one of those, it grows no farther north than Texas.

You're getting excellent growth with 16 hours of light, I wouldn't change it.

metsolt wrote: ↑Sat Oct 17, 2020 3:50 pm Thank you!

I have one question for anyone. I currently have the light on for 16 hours a day. Would it make any difference if I increased it to 17 or 18? Or should I do it with time?
I found different information about this, some say 14 hours is the best, but others say 18.
Starting with it that it's not too much, would it bring any benefits at this age?

I don't know about any cacti living in conditions with more than 16 hrs of daylight (maximum during summer days: these from Canada or Patagonia) so I wouldn't increase it any more. Cacti need some darkness too. I stick to 14 hrs/day for my seedlings.

greenknight wrote: ↑Sat Oct 17, 2020 11:54 pm Cacti use CAM photosynthesis, their stomata open to let in CO2 at night - they need the dark time to breathe! Too long a light period could actually suppress growth, as the plants would be unable to take in enough CO2. As you found, there are differing opinions about what the maximum period of daily light is. Likely the optimum varies with different species - those that grow in the higher latitudes, where the days are much longer in the summer, are undoubtedly adapted to thrive with longer days. L. williamsii is not one of those, it grows no farther north than Texas.

You're getting excellent growth with 16 hours of light, I wouldn't change it.

Thank you! That's what I had in mind. I saw a person growing LW under 18 hours of light a day and wondered if the plant had enough time to rest.
I also read about people starting them in 25 hour cycles. I guess people just have different opinions.

7george wrote: ↑Sun Oct 18, 2020 3:01 am

metsolt wrote: ↑Sat Oct 17, 2020 3:50 pm Thank you!

I have one question for anyone. I currently have the light on for 16 hours a day. Would it make any difference if I increased it to 17 or 18? Or should I do it with time?
I found different information about this, some say 14 hours is the best, but others say 18.
Starting with it that it's not too much, would it bring any benefits at this age?

I don't know about any cacti living in conditions with more than 16 hrs of daylight (maximum during summer days: these from Canada or Patagonia) so I wouldn't increase it any more. Cacti need some darkness too. I stick to 14 hrs/day for my seedlings.

Thank you! I will keep this setting, then. After all, nature can't be rushed!

Okay, I updated this thread more than I planned.
Today's one month since first germination so I decided to take a picture.
I played with the shadow when taking it to make development more visible.

The one in the center is the most developed seedling in the pot. I noticed some 4 (or 5) areoles developed and grown apart from each other as the seedling is plumping up.
I am slowly drying out the soil and as a result of opening the bag I got algae growing, but it didn't affect the seedlings so far.

And most importantly, there is no mold in this or any other pot with seedlings. I guess I'm lucky/doing it right.

Off topic:

I wasn't sure where else to post so I'll post here
This is one of my Astrophytum mix seedlings
I am absolutely hopeless when it comes to Astro ID, but this has a very weird growth pattern. Also, it's very glow growing, this being almost 7 months old. Other seedling are waaaay bigger now.

Capricorne hybrid

Today is 2 months from first germination.

11 survived, no casualties since my last update.
There are different types of growth on the soil, none of which affected growth so far. I am not sure what this orange growth is. Do you recommend that I sprinkle sand/gravel over the soil? I am too afraid to scrape this off if I decide to top dress it.

Most of the seedlings already have 5 areoles and 5 sides developed. One is slower than the rest and has a darker color to it, almost like a grown plant. Two seedlings touched already. When I was sowing, I tried to place them evenly to avoid this, but they chose to germinate in a clump, leaving empty room in the rest of the pot.
I recently increased the temperature, day going from 25-27°C and night temps around 20-22°C. I lowered the light slightly 2 weeks ago, they don't seem to complain.

Overall, these are growing faster than I expected. I have some Epithelantha growing with way less development showing.

metsolt wrote: ↑Wed Nov 04, 2020 3:44 pm I am absolutely hopeless when it comes to Astro ID.

Luckily there are only a few species, assuming we don't count all the hybrids. And it is easy to exclude A. caput-medusae, A. asterias and basically also A. myriostigma / A. coahuilense already at a young age from the others. That's about half of the species already out of the way.

very nice. keep them going. very cool

Quick update:

I decided to carefully scrape algae off the top of the soil where I could and put in sand/gravel as top dressing. They're 2 and a half months old now.

Looking good, J! Are they out of the bag now?

Thanks!
No, they're still in the bag. I'm not sure how much longer, but I won't take when out before New Year's. Probably won't harm them if I leave them in a biiit longer

Hello everyone!

Here is the progress today, 3 months from germination.I must say they're coming along really well. What I noticed is that the number of "sides" varies. Some have 4, some 5 and some 6.
Overall, they're moving faster than expected. Not much else to say so far.