Hi everyone,

I'm thinking of venturing into the wonderful world of cacti in spring next year.
Most likely I will get a packet of Bridgesii seed and try to grow a bunch from seed, though I might also try to get my hands on some cuttings from good named clones.
Either way, I live in Belgium where the weather is overcast throughout the majority of the year. Think lots of grey skies, little sun and a lot of rain, similar to the infamous dreary weather of England.
For that reason, I am wanting to keep my cacti indoors, and I'm considering a modest setup with some grow lights to be able to better accomodate them.

I've read fluorescent lights are A-OK for raising seedlings, but I didn't find any conclusive info on which lights to use after the seedling phase. I read a discouraging post over at the shroomery of someone who claimed to have wasted a ton of money trying out all sorts of lighting for indoors growing, and swore you needed high-intensity energy-burning metal halide and high pressure sodium lights similar to those used for growing weed to get trichocereus cacti to grow well indoors.
I've seen some other people using CFL's for indoor grows, which seems a lot more economical if that works..

Can someone with more experience give me some advice? I know next to nothing about grow lights, and want to make sure I can provide the best possible environment (while remaining economical) for my future buddies before I proceed any further.
I'm also considering setting up a greenhouse in my backyard, maybe that would already boost the sunlight enough to provide decent growth?
I'm not looking to get the absolute fastest monster growth or anything like that, just want to make sure they are healthy and will thrive. I'm patient enough to be satisfied with slower growth, as long as my plants remain healthy

I have grown cacti in Britain. I was fortunate enough to have a south-east facing windowsill of a reasonable size and they would grow like the proverbial clappers over the summer. This second floor window (with the ground floor being floor zero) also had the benefit of avoiding winter shadow. After taking cuttings I started running out of space!

As a result, I can't offer any advice about using lights for growing but want to raise the idea of using LEDs for energy efficiency. And if you search through entheogenic-gnosis' posts, you'll see that (s)he has used a light box for cactus growing.

Also bear in mind that, apart from enjoying the sunshine, Trichocereus cacti are not quite like your average perception of cacti. They'll grow like tomato plants (sort of) during the summer with a bit of nurturing. It just doesn't matter if you forget to water them.

Is the weather really that bad in Belgium? Maybe I was lucky to have lived in a relatively sunny part of the Sceptred Isle

A light similar to this worked well for me the first year, in an area about .35 square meter (4 sq feet).

http://www.ebay.com/itm/...?hash=item41b857b240:g:Q~4AAOSwXeJYHDXo


This lady has some decent videos about caring for Trichs and other Cacti in Northern climates.

Salut

I used to live in Belgium, and now I live in Germany, probably about the same latitude as you are and I am successfuly growing cacti outdoor.

You say you have garden,then I wouldn't waste the electricity on indoor growing to be honest. San pedro is a relatively fast growing cactus and starting from seed you can probably harvest your first dose in about 7 years (starting from cuttings a bit faster, depending on the size of the cutting off course). If you buy a greenhouse then you will be able to harvest even faster.

Only for sprouting the seeds would I recommend a cheap CFL bulb (6500K, cool white). You can use a good seedling mix to sprout them, very very easy! Then introduce them very slowly to the outside (so start the seeds in February). Watch out because they can easily get sunburned if you put them in direct sunlight.

If you realy want to grow them indoors my guess is that you will need high wattage light bulbs, like the ones used for cannabis growing. Typically you would use metal halide bulbs for growth. I don't think you can make them happy under CFL lights, you have to try to imitate the sunlight.

So the most effictive way would be:
April-October: OUTDOOR
November-March: INDOOR (Metal halide)

I personally put my cacti to sleep in winter, that means put them in a cold, dry basement with some natural light and they will enter dormancy. If you buy a greenhouse you could heat the greenhouse in winter and keep them in there.

After the seedling stage a cactus will typically grow about 30cm per year in our climate (whitout a greenhouse), I think that's ok. So if you sprout a handful of brigesii seeds you will have a bunch of nice cacti about 5 years later.

Have fun!

I started some peruvian torch from seed in March and kept them in an unheated greenhouse over the summer. They are now in a cold room with indirect natural light. Should I stop watering them? They are about 1 cm tall and quite fat. Dont want to risk them dying over the winter, but also worried they might get moldy if kept damp and cold.

I should've added in my first post that it can be beneficial if you put them under CFL (I did it under 125W) during their first winter. Just watch out because you can burn them even under artifical lighting.
If you keep them in a cold room then I would definately reduce watering asap, let the substrate dry out, they can handle it. You have to watch and observe though and if they start looking too dried out you can give them a tiny bit of water.
Don't let them get too cold since they are still so small. Not below 8°C. As they get older they can handle very cold temperatures, even short times below 0°C, but then you have to make sure they are completely dry.
Please search online also because this is just my personal experience.

I second bringing them indoors in a low lit and/or dark/minimal light room, cooler, for the winter so they can go dormant. Prevents thin growth/etiolation/ odd shaped cacti, and keeps nice, fat, healthy cacti for colder-climate folk.

https://www.thevespiary.org/rhodium/Rhodium/Vespiary/talk/index.php/topic,69.0.html

^^ The above is a excellent article on northern climate care for cacti, by one of the foremost cactophiles, M.S. Smith

Cacti always like real sunlight the best, as much as they can get, assuming they are slowly and properly acclimated to it.

You'll want to start seedlings indoors under lights for the first year or two, be sure to slowly acclimate them to the indoor lights too. I put mine on shelves in front of the window to make sure that are getting some real sunlight to supplement the artificial lighting. Flourescents work fine for this, I grew mine under a T5 flouro lamp for a long time but recently upgraded to LED.

Once your cacti get 3-4 inches tall they should be good to go outside in the spring/summer when the weather warms up, again acclimating slowly. You will most assuredly want your cacti to spend as much time outdoors as possible when the are mature enough to do so. Now matter how overcast it is, the billions of kilowatts of the sun outperform even the very best of lamps.

Anything short of a proper professional grade cannabis grow lamp (MH,HPS or comparably powered LED/Induction) is not going to be suitable for growing mature cactus indoors. Anything less will cause etoliation.

If you can manage the greeenhouse that is absolutely your best bet, as this will keep the rain off them to prevent rot and keep them from freezing in winter plus allow them full access to direct sunlight year round.

If the greenhouse is not an option the best bet once they are mature enough to go outside is to just bring them in and let them go dormant for winter as others have mentioned.

I'm in a very similar position of looking for suitable lights for a small shelf cacti grow op. In reading up on artificial grow lighting, I've learned a number of things that were entirely new to me.

The most surprising thing I've learned is that at the power levels where plants begin feeling something, MH and HPS lamps are the most efficient lamps, period. LED is second (yes! LED is NOT more efficient than MH or HPS at this power level), and fluorescent lighting is a distant third.

The second most surprising thing I've learned (and one that is definitely important to keep in mind) that when we're talking about outside daytime illuminance, especially with cloudless skies, those values are off the charts. I mean I knew it as data, that we perceive intensity on a logarithmic scale, since I know photography... but I never really thought about it how ridiculously puny our everyday light sources are compared to outdoor light. Which means, if you intend to grow any plants under artficial light, get ready to break out the big guns.

Now what people say is that plants only utilize specific wavelengths, and using LEDs that only emit these you can get away with lower overall power, even though it's not more efficient from a physical perspective... But as far as I understand the science is still dodgy around that question, and taking the fact that LED is maybe an order of magnitude more expensive per Watt than high-intensity bulbs, I'm pretty sure there's good reason industrial growers all use high-intensity - if you really could lower power consumption significantly with LED, it would be most useful in industrial scale environments.

You can get smaller MH bulbs - 250W or 400W ones. I think it's best to get a good estimate of average illuminance in an American desert during daytime, and calculate the necessary luminous flux (lumen value) of the lamp based on its distance from the plants - and then select the correct wattage accordingly. (I personally haven't done that yet but it's exactly what I'll do.)

Regarding watering over the winter (sort of), I'm experimenting with rooting a few spare cuttings of T.peruvianus, T. pachanoi and T. ?scopulicola in a tub of about 1/2 - 1" (1.5 - 2.5 cm) of water on a west-facing windowsill in northern Europe. There is a radiator below, they don't seem to mind too much at the moment. I guess we'll see how they do.

When given adequate daylight, Trichocereus species (or at any rate, the ones I have) don't mind a bit of water through the winter. With adequate sunlight and warmth, they'll carry on growing, albeit more slowly. WARNING! Other species may be far less forgiving.

Thanks for the info regarding LED vs MH. I'll carry on relying on that ball of nuclear fusion in the sky, methinks! If you do the calculations, PsyDuckmonkey, please share your workings

I live near Belgium and I grow my cacti outdoor since seven years now. I began with two years old specimens and harvested the first two San Pedro 2 years ago, they were perfect!

I begin to water them in the early days of april and put them in my garden a few days later.

To avoid a late frost or over-watering, I have to watch the weather forecast and don't hesitate to bring them back indoor during a few days in case of low temperatures or heavy rain.

Approximately in the last days of october, after a month without watering, I bring them back in my veranda (low temperature but no frost, no water) were they wait for the spring to come back.

To this day, my bigger specimen is two feet tall and about 3 inches width. So, it's not so fast than it could be but it definitely works!

Okay so illuminance is luminous flux per area.

Outdoor daylight illuminance values from Wikipedia:
Clear skies, direct sunlight: 120000 lux
Clear skies, shade (illumination from blue sky): 20000 lux

I looked at two Philips MH (vegetative grow) bulbs, one 250W and one 400W:
250W MH bulb: 20500 lm
400W MH bulb: 32000 lm

Assuming perfect targeting of the light beam (as in a grow box lined with reflective silver mylar): ideal grow area = lamp flux / target illuminance

250W MH bulb: 0.17 m2 direct sunlight equivalent, or 1.02 m2 shade equivalent.
400W MH bulb: 0.27 m2 direct sunlight equivalent, or 1.6 m2 shade equivalent.

Trichs really do need plenty of light. Not terribly economical to grow indoors.

Hydro Lophs do fine under LED, and make a lot of sense for cold-climate urban folk.


pic from this morning

Here's a visual of my little mini farm to give you an idea of what I'm talking about. This is about the extent of size you'll be able to realistically achieve under lights without skyrocketing the power bill. Come springtime all these babies get to start living outside and the shelf will be used for the next batch of seedlings and grafts.

@Biawak, yay XHTTL tek!

@dreamer042, isn't that light too concentrated on the center of your garden?

That's great set up dreamer!

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I recently had a large amount of space become available, but I only have 2 1000W high pressure sodium boxes with balasts, and a T-5 box with 8 T-5 bulbs in it.

I know my set-up is "makeshift", but it's actually done ok for what it is.

Right now my cacti are set up in a smaller room, they receive partial Sun from an east facing window, and they have the T-5 box and another regular lamp for light. This set up has done well for what it is, however, I want to expand, next grow season my rooted clones from last season should kick into gear and will eventually require more space.

I'm not sure how to incorporate the 1000W sodium bulb boxes into my cactus grow...I was using all these lights for cannabis, but since in my state you can easily buy cannabis at the store at any given time, I decided growing cannabis was a waste of time and energy, I'm perfectly happy just buying my cannabis. Then again, for me cannabis is like coffee for most people, it's not a real intoxicant, it never impairs me, but I need it to get through my day. You don't see coffee drinkers growing their own beans or obsessing over the coffee plants in the way cannabis smokers do, which may be why this behavior seems strange to me, cannabis is so normalized that most don't think of it as anything "special"...I'm getting off topic though.

The point was, I had these lights for cannabis, and now I'm incorporating them into trichocereus and lophophora cacti growing. I'm living in a state where the winters are full of heavy snow and freezing temperatures, so outdoor is not an option.

Any ideas on the most efficient and effective way to use 2 1000W high pressure sodium bulb boxes and a T-5 box for cacti?

(The picture shows my currant set up, a T-5 box and an open window....)

-eg

I actually set it up such that all my smaller/weaker cacti that were progressing slowly and looking sickly on the outskirts of the previous flouro setup got put right in the center on this one and they've all been recovering beautifully and put on solid growth since making the change. It's really just a matter of making sure they are adapted slowly to the higher intensity lighting. They really do like all the light they can get (so long as it is introduced progressively).

Those 2 1000 watters will easily keep your garden growing strong, even those large trichs. It looks like your footprint is pretty small, so that should be plenty enough power. I'd just go ahead and hang the HID lamp(s) from the ceiling above the setup you already have going. Of course, running those 2000 watts will have a pretty significant impact on the pocketbook when your electricity bill comes in (if you already had em going for a cannabis grow, this is probably not that big of an issue though).

Introduce the light gradually either keeping the cacti on the peripheries and slowly moving them closer to the center, or utilizing some kind of shade cloth and slowly giving them a bit moar time in the direct lighting each day/week.

P.S. - You clearly don't know many coffee snobs of my caliber, I'm even moar picky about my coffee than I am about my weed. And I'm pretty darn picky about my weed.

Thank you! I appreciate the advice very much.

When I was growing cannabis the two 1000W high pressure sodium boxes were incredibly expensive, and, if I decided to turn on too many electrical devices it would trip the fuse box and take out my power until I turned the switches in the fuse box back on...

Do you think just one of the 1000W boxes could be efficient?

-eg

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Perhaps my "coffee drinkers" metaphor doesn't really hold up...

it's hard to think of a good comparison...

...but if you can glean my intended point, I think it works...though I'll be searching for new models or metaphors to express my feelings on this matter in the future...

For your current setup/footprint I think one of those 1000 watters is plenty. Just for winter tho, come spring/summer be sure to let those beauties get some sunshine.