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Hello, everyone! 4 months ago I sewed saguaro seeds in a mixture of sand, perlite, and potting soil and placed them inside a sealed ziploc bag. The seedlings have grown well and developed healthy spines, and I have opened the bag and introduced them to their surroundings. They currently receive about 1200 lumens of light per square foot for 16 hours/day and maximum temperatures of 80-85 degrees. Can anyone provide advice for the next growing steps? Should I increase light intensity? Repot into individual containers? Begin watering with dilute fertilizer? Any suggestions would be greatly appreciated! Please see the below photo of the seedlings for reference.

Don't repot yet. Just keep them in there for a year or so. I would say when you repot them, it is probably best to keep multiple in the same pot. Saves you room, the pots dry out a bit faster as there are more plants taking up moist, and they might compete with eachother in a growth race (well, that is what the myth says...).

Don't keep the pot constanly moist from now on. Just allow the pot to dry out in between waterings. The seedlings are strong enough to survive a short period of drought when things are not too hot and the light intensity is not too high.

Aiko wrote: ↑Mon Apr 18, 2022 9:04 pm Don't repot yet. Just keep them in there for a year or so. I would say when you repot them, it is probably best to keep multiple in the same pot. Saves you room, the pots dry out a bit faster as there are more plants taking up moist, and they might compete with eachother in a growth race (well, that is what the myth says...).

Don't keep the pot constanly moist from now on. Just allow the pot to dry out in between waterings. The seedlings are strong enough to survive a short period of drought when things are not too hot and the light intensity is not too high.

Thanks for the quick response Aiko! Do you have any advice on increasing light intensity or adding fertilizer? I am growing everything under artificial lights (outdoors is not an option for me) and I have the ability to increase the lumens from about 1200 lumens per square foot to 1600 lumens per square foot.

I don't have an advice regarding light. I don't use artifical lighting. But you could increase the level and see if the plants start to turn purple / red due to too much light and are stressing. If that happens, you should tone it down a bit again.

Aiko wrote: ↑Wed Apr 20, 2022 6:39 pm I don't have an advice regarding light. I don't use artifical lighting. But you could increase the level and see if the plants start to turn purple / red due to too much light and are stressing. If that happens, you should tone it down a bit again.

Thanks for the input. I will probably wait a bit until I see signs of growth with them outside the bag before giving them additional lighting.

Light is OK, little pink on the body is fine, shows that light is sufficient.

Next step after ~ 50 years: moving to Arizona.