how long in the dark

philwilliams · Post by **philwilliams** » Wed Jul 18, 2012 10:16 pm

I'm growing some seeds in a light box for the first time. Can any one tell me how long the light should be off for. Currently the lights are on for 21 hrs off for 3 hrs. Is this too much ?Thanks in advance

Tony · Post by **Tony** » Wed Jul 18, 2012 10:38 pm

I run mine 14 hours on. This works great for me.

Alber khan · Post by **Alber khan** » Thu Jul 19, 2012 3:58 am

Mine are on about 15 hours.Works for me too.

philwilliams · Post by **philwilliams** » Thu Jul 19, 2012 10:27 am

Ha , 21 hrs was a bit of overkill ! thanks for the advice.

CactusFanDan · Post by **CactusFanDan** » Thu Jul 19, 2012 2:52 pm

I have my lights running from 6am to 9pm, soooo... that's 15 hours.

21 hours is a bit of an overkill, but you never know, it might result in better growth. You could try it out.

Tony · Post by **Tony** » Thu Jul 19, 2012 3:17 pm

I used to propagate soft corals and tried exceptionally long photoperiods on them but I never saw any improvement in growth rates. I dont think cacti would be any different.

I have my seed propagator box inside in my home office. At first I ran into overheating problems even though I generaly only grow seeds in the coldest part of the year, December through about april. I tried venting (drilling holes and leaving the doors open) but by running 14 hours and turning the lights on late in the evening and then turning them off the next morning I was able to keep the temps right where I wanted them for nice consistant growth and dont have to worry about stressing/cooking them when we have a heat wave in february.
I can literally sow the seeds in baggies, put them in the box, set the timer and forget about them for three months.

philwilliams · Post by **philwilliams** » Thu Jul 19, 2012 3:19 pm

some mam sedlings emerged and went pink straight away, one ot two that were shieleded by larger bits of gravel stayed green, which started me thinking I may be overcooking them. I'll go with the consensus, though maybe the lights are too bright even for only 14 hours. We'll see anyway.

iann · Post by **iann** » Thu Jul 19, 2012 6:10 pm

I can literally sow the seeds in baggies, put them in the box, set the timer and forget about them for three months.

I can't! I have to look at them every day

I germinate with the lights on for 20 hours (at night) to help keep the temperature fairly even and then reduce the lighting hours as well as shifting it into the day. After a month or two I also increase the power of the lights.

Lots of Mammillarias go bright red in quite moderate light. For many of them you just have to work through this stage because they won't develop good spines until they get bright light and they won't tolerate bright light until they have good spines

RobR · Post by **RobR** » Thu Jul 19, 2012 6:58 pm

I have had good results with 24 lighting. I know it sounds crazy but I have grown many batches of seed over the years and they start life under 24 hr lighting for 6 months or so before I move them outdoors into normal lighting. They seem to adjust easily.

Tony · Post by **Tony** » Thu Jul 19, 2012 7:23 pm

RobR wrote:I have had good results with 24 lighting. I know it sounds crazy but I have grown many batches of seed over the years and they start life under 24 hr lighting for 6 months or so before I move them outdoors into normal lighting. They seem to adjust easily.

Interesting. Any idea if they grow any faster this way?

RobR · Post by **RobR** » Thu Jul 19, 2012 10:37 pm

I do get a little speedier growth on them. I use generic plant/aquarium bulbs in a 4 foot ballast with the light about 6 inches from the pots. Plants don't etiolate at all and spine development is good. When I put them outside they go under 50% shadecloth. The last couple of batches I did last year were sown outdoors under the shadecloth in completely natural conditions. Germination was not significantly better or worse than the 24hr under light approach.

philwilliams · Post by **philwilliams** » Fri Jul 20, 2012 8:08 am

clear as mud now, I think i'll go for 19 hrs light on now

Alber khan · Post by **Alber khan** » Fri Jul 20, 2012 9:02 am

I dont want to hijack your thread or anything,just want to ask that 3 days ago i planted G.stellatum seeds in a small plastic pot.I soaked the soil,like i really wet it.After one day in the baggie the soil started to expand like dough and today its even more expanded with big cracks in the soil.What is causing this?The plant pot is placed on top of little water in the baggie.

iann · Post by **iann** » Fri Jul 20, 2012 11:48 am

Alber khan wrote:I dont want to hijack your thread or anything,just want to ask that 3 days ago i planted G.stellatum seeds in a small plastic pot.I soaked the soil,like i really wet it.After one day in the baggie the soil started to expand like dough and today its even more expanded with big cracks in the soil.What is causing this?The plant pot is placed on top of little water in the baggie.

Soil is rubbish. Wasn't something from a bag called "cactus soil" was it?

Switch to something that doesn't expend like dough, isn't 90% peat, and won't kill your new sprouts. Also, don't stand the pot in water. It is in 100% humidity, it doesn't need to be underwater as well. Slightly moist (plus humid) is sufficient for most small cactus seeds to germinate, and certainly for sprouts of G. stellatum to thrive in.

promethean_spark · Post by **promethean_spark** » Sun Jul 22, 2012 11:08 pm

I run my lights at night time, and for a shorter time during the summer because it gets hot in there and more in winter to keep them warm. Usually 18 to 12 hours on. I guess my seedlings in the propagator might be mixed up as to what time of year it is...

As I understand it, CAM plants won't open the stomata during the daytime, so perhaps they can respire better if they get at least some off time.

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