I'm growing 2 year old bridgesii indoors under T5 flouros. I've been running the light 24 hrs/day. Is there an advantage to having a dark period?

I don't have any useful info, but I'd love to see pics of your cacti.

I'm planning on growing my own bridgesii this year.

not that i'm aware of.
i used to do my seedlings and grafts under 24 and had great growth

Not a great photo, but you get the idea. I have about 65 bridgesii.

The larger two are San Pedro.

how far from the lights are they?
if the floro bulbs are not too hot they should be 4-8" away

ooh, I have a feeling this will take a while for me.

Nice plants though.

18 hours of light was plenty for the ones I cared for, more natural to have a
dark period. Do you water yours in wintertime?

I water them ever 2 weeks. They're still young, and would probably die if I stopped watering. After 3 weeks without water they get drawn in, and skinny. I need to lower the light like dg mentioned, and maybe switch to 18 hrs.. They'll go outside this summer, up till now they've only seen artificial light.

I know 24 hrs lighting is used for MJ with good results, yet a dark period is essential for the plants development. I suggest you give them at least one hour of darkness so they can metabolize

Looking good anyway.

Peace and love.

i recommend a min of 30 percent shade cloth for when they finally go out.
they will sunburn like newborn babes

CAM is worth looking up. Cacti seem to do very well with a dark period, I would use six to eight hours. http://en.m.wikipedia.or...sulacean_acid_metabolism

Cacti (and all plants) do need a dark cycle! 24 hour light will work okay at first, but eventually it catches up and the plant will suffer. An 18/6 light cycle would be a good compromise.

As AlbertKLloyd mentioned, check out CAM metabolism, which is a little different than metabolism in most other plants. Cacti open their stoma for gas exchange at night, and actually absorb CO2 and store it in a converted form within the plant, which is then used for photosynthetic production during daylight hours. Pretty cool, part of the way cacti have adapted to arid climates and conserve their water (stoma are closed during the day to prevent water loss). CAM also helps adapt them to hot temperatures and plenty of sun.

those guys are to thin, double the light at least.

this is my setup for seedlings.1x250+2x100 CFL's look how close the lights are.there is 1x100w missing thats why you cant see it in the picture.

So what about growing them by a window? Until the winter is passed.. You guys make it seems like they need BLARING SUN BEAMS. Should I get a greenhouse instead, for more direst sunlight?

a greenhouse is worth every penny and square inch.

I agree those guys are too skinny. Oneistheall thats how its done..thats a really nice setup..another year I hope mine are like that.

In my experience you will have 6-12 month old cacti that are still only 1cm tall(unless you live somewhere with intense sunlight. Start them under lights and then once they are established bring them outside of summer. I am in canada and my peruvianus grows just great without any lights. I bring them outside for half the year and they grow like crazy then I bring them in and let them hybernate for the winter. I am in a warm area of canada though, zone 8b and could leave them out all year probly but most places in the US you should be fine for the summer.

All my baby achuma seelings I have indoors under lights in a greenhouse type setup becasue in my experiece they dont do much in a window other than sit there as tiny little blobs.

Good lighting can make a big difference.

With good care, lighting and feeding they can grow a lot faster than people tend to realize.

I have seen them grow from seed to be a foot tall and 2 inches wide in about year in the fastest cases. Some grow kind of slow and so would be about half that in a year.

do you guys feed your seedlings? I usually don't till they are a year old...
What do you guys like best? I had good experience with 10-10-10, and for older specimen slow release fertilizer worked pretty well.