Lighting Intensity/Choices For Indoor Setup?

Do-it-yourself projects such as greenhouse or shadehouse builds and related topics.
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Ferocactus
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Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Hi,

I'm setting up an indoor grow house for my cacti, and they are all about the same height (12" from base of pot to plant's top), and are mostly Ferocactus and Echinocactus sp. I am intending to place them in my following setup:

It is a PVC frame 36" long x 36" tall x 20" wide; it's covered on the 4 vertical sides with 6 mil Mylar; for lighting, I have two non-high output 36" Coralife Dual Lamp T5 fixtures (extras from my planted aquarium) resting on two bars of the PVC frame; the four bulbs I'm using are Oddysea 39W 6500K T5 bulbs.

What level of light intensity would be good for barrel cacti? The brightness seems a little low: should I lower the height of the lamps, and if so, by how much? Or would it be a good idea to place Mylar siding over the top to make it fully-enclosed? Also, is non-high output lighting from T5 fixture suitable for growing cacti?

I'm really unsure as to the proper height of the lamps to provide the best intensity (this is by far my greatest concern), or if height even matters with so much Mylar siding in use; I'm also unsure if my specific bulbs are suitable for southwestern barrel cacti.

Could someone please advise me? Thank you so much!
It's practically impossible to grow healthy barrel cactus species here outdoors... :(
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Ferocactus
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Does anyone have a recommendation for a specific lighting source, it's wattage, and how high I should place the lamps in my Mylar-sided grow tent?
It's practically impossible to grow healthy barrel cactus species here outdoors... :(
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eulaspiegel
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by eulaspiegel »

I can't really give any super specific or long term experiences, but I have been using the LED grow lights by spider farmer and mars hydro to grow cacti indoors, in part also over the last winter. So far it has worked well, they are really strong and I even managed to burn some plants because I wasn't careful with the distance. One good thing is they come with a dimmer, so the light intensity is really easy to regulate. Also since they're LED lights the light intensity per used wattage is great and they are supposed to have a really long lifetime. One thing to keep in mind is that these types of lights were optimised to grow other plants (like vegetables or Cannabis), so potentially you might have to supplement with some UV-b light if you want completely natural looking cacti, I think how well they respond to artificial light depends on the species.
Growing mostly under LED lights, in northern latitudes. Especially interested in stem succulents and caudiciforms. Dreaming of my first greenhouse.
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by mikethecactusguy »

Mike The Cactus Guy
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Ferocactus
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Thank you for letting me know!

I really can't understand the technical details of light intensity, and I'm confused as to how to apply them for my current setup. The only fixture I could find that would fit my grow house frame is the Durolux DLED824W LED Grow Light (1'x2'), but I still don't know if this would produce enough light or intensity to grow healthy SW U.S. barrel cacti indoors all-year-round.

Would the four T5 lights I have be enough? I just don't know what to think: there has to be a specific lighting fixture that would work for a 3'x3'x1.75' grow house, but I just don't understand what would work. I'm so frustrated: not angry, just really stressed and confused. (v_v)

I live in Wisconsin, and it really sucks for growing cacti, since it is incredibly humid in the summer, and keeping them outdoors is only viable for maybe half the year. Every time I've tried to acclimate my plants into full sun, they got severely burned, and I almost lost one (half of the plant is completely scarred). I hate this state, but it's where the work is... Growing cacti indoors is my only option, and it's one of the few joys I have in life, so it means a lot to me. I just don't know what to do, despite all my best efforts.
It's practically impossible to grow healthy barrel cactus species here outdoors... :(
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by mikethecactusguy »

you should post a few pictures of your set up and a few of your outdoor area. It would help identify your needs
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Download »

Ferocactus wrote: Tue May 04, 2021 12:10 am I really can't understand the technical details of light intensity, and I'm confused as to how to apply them for my current setup. The only fixture I could find that would fit my grow house frame is the Durolux DLED824W LED Grow Light (1'x2'), but I still don't know if this would produce enough light or intensity to grow healthy SW U.S. barrel cacti indoors all-year-round.
Scroll down the thread. Many of the details provided were wrong.
Would the four T5 lights I have be enough? I just don't know what to think: there has to be a specific lighting fixture that would work for a 3'x3'x1.75' grow house, but I just don't understand what would work. I'm so frustrated: not angry, just really stressed and confused. (v_v)
There is no reason to use fluoros in this day and age. They have a poor lifespan and poor efficiency. LEDs are the only serious choice nowadays. Even the cheapest bargain bin LEDs are more efficient than fluros.

I am uncertain how you are having trouble finding lights. If you go and buy cheap LED downlights (which are quite often less than $1/watt and less than $1/100 lumens) you can just keep adding lights until you get the required light level (which will be something like 10,000 lumens per m^2). Pick the lights with the greatest lumens per watt value to cut down on electricity.

If you feel more technical, build some COB LED lights. They will be cheaper than every off the shelf grow light and probably more efficient too. Literally just follow one of the millions of guides for putting COB lights together. It doesn't matter that most are aimed at people growing weed: it still makes plants grow.
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Ferocactus
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Thank you, everyone!

I've attached some photos of my current grow house frame for size, the east window in my basement, and part of my garage space. My basement only gets as low as 68˚ in the winter, and the garage is always the same temp. as outside (-10˚ to 32˚ during the winter).

I don't have too many cacti at the moment, as many have died over the past couple years due to a combination of factors (trying to keep them outside in WI's 80%+ humidity summers, low light + underwatering/overwatering in the winter, lack of options for a true dormancy period, scarring, etc.). I've been keeping cacti for over 10 years, but things rarely work out well despite my best efforts; I know my stuff, but it is really difficult to care for these plants properly in WI ( 12-year-old 6" F. wislizeni in the corner, and the 2" F. stainesii is the same age, both are stunted). I could probably afford better grow house/overwintering options and equipment if I didn't have such a restricted budget; a decent walk-in polycarbonate greenhouse would solve so many issues. :lol:

I don't know, maybe I don't have what it takes to care for barrel cacti in Wisconsin after all; I really want to move southwest, but life happens. Not sure what more I can do.
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It's practically impossible to grow healthy barrel cactus species here outdoors... :(
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by jerrytheplater »

Is that framework what you would want to heat overwinter as discussed in your other thread? Should be doable. Just insulate the sides with solid insulation sheets and seal with duct tape. You could use the expanding foam in a can to hold it all together.

My winter mins get to neg 5, but only for a few days if even. I keep a bunch of bone dry cold hardy cacti in that unheated garage in front of a south facing window over winter. I don't protect them beyond being in the garage which does get a touch warmer than outside due to the sun warming it.
Jerry Smith
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45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Ferocactus
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Actually, the PVC frame pictured is what I'm hoping to use as a grow tent. I have some 6 mil Mylar sheeting that I have yet to affix eyelets to, and then string everything up onto the frame like a shower curtain. I have two Coralife T5 Dual Lamp fixtures that rest on top quite nicely, but I think they're only good enough for winter dormancy lighting.

I could definitely make another PVC frame for winter dormancy, like you've suggested; or I could just use this one, and try my luck again with keeping my plants outdoors in the summer. Do you think the lighting from the fixtures might bring the heat up a bit if they were kept inside the insulated box (covered with an insulation sheet over the top)?

I wish my barrel cacti could survive temperatures in the single digits; there are Opuntia fragilis here in WI, but I don't have any at the moment (they produce such beautiful flowers, and fruit too).
It's practically impossible to grow healthy barrel cactus species here outdoors... :(
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Download »

I'm still confused by what trouble you are having with lights. Yes, that three armed thing is probably inadequate, but otherwise you haven't made clear what the trouble is.
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Download wrote: Sat May 08, 2021 6:02 am I'm still confused by what trouble you are having with lights. Yes, that three armed thing is probably inadequate, but otherwise you haven't made clear what the trouble is.
I simply don't understand how LED grow lights would compare to T5 HO grow lights in terms of intensity (LEDs seem to be less bright than T5 HO, but I've read that they have a higher intensity); everywhere, there is so much conflicting info.

I don't know how to compare T5 HO to LEDs with all their combined properties and measurements (wavelength, PPFD/PAR, lumens, watts, etc.) in such a way as to know what would be suitable for my current grow house setup. I know I'd need a PPFD/PAR rating of about 1500 μMol/m²/s to mimic full sun, but all the sellers I've messaged on retail sites simply don't have this information for their products. I'd need a PPFD/PAR meter, but the cheapest ones are hundreds of dollars, which is absolutely ridiculous.

I've just given up for now: I found my old mini greenhouse frame, made a makeshift covering, put my currently-rooted cacti inside, and left them on the east side of my house. My newly repotted cacti are inside under the grow frame right now, and all the LED light's focus is on my new F. latispinus seedling. Hopefully I can prep it for leaving it in full sun in the greenhouse before the end of June.

If I can successfully grow just a single, healthy F. latispinus plant here in WI, that's good enough for me (it's my favorite species); after over 10 years with little success, I'm tired of babying my other cacti, only to see so many of them kick the bucket. If these ones in the greenhouse survive, great. If they get sunburned, or rot in the winter, that's the breaks.
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by jerrytheplater »

Your Coralife T-5 HO should light up in your cold winter. Regular lamps won't strike. If you look at aquarium LED fixtures, you can get some that will require you to wear sunglasses. You can get some that are really dim. It depends on the money you want to pay. If you are just trying to provide light in winter you may be fine with the Coralife. And yes, I'd try and locate the ballast outside of your enclosure. You could rewire the fixture with an external ballast. Just make sure to use ballast grade wire, not just any old grade of copper wire. Its the insulation and high voltage you need to consider. You didn't say how long your fixture is.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Ferocactus
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Ferocactus »

Those are excellent ideas, thank you! Actually, my Coralife T5 fixtures are just standard (not HO, though I wish they were), and they're 36" long; they rest on top of the two PVC pipes of the frame perfectly, without any bowing to the frame.

Do you think I might have trouble starting up the fixtures in temperatures below freezing, seeing as they are not HO fixtures? I was thinking of putting the fixtures on top of the frame as usual, but also put a board of insulation over the top of them to keep what minimal heat is produced inside the grow tent. They don't get too hot to touch during operation, but I'm now a bit worried that they won't perform well in freezing temps.

The ballasts are built into the inside frame of the fixtures, and I've never had any understanding/comprehension of circuitry (in HS Physics, I remember failing miserably trying to make even a simple circuit with a transistor). To be safe, I just might have to keep the whole setup in my basement with a fan running onto the plants, hopefully to bring the temp. down a bit; I really don't want risk my plants freezing solid.
It's practically impossible to grow healthy barrel cactus species here outdoors... :(
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Re: Lighting Intensity/Choices For Indoor Setup?

Post by Download »

Ferocactus wrote: Sat May 08, 2021 8:05 pm I simply don't understand how LED grow lights would compare to T5 HO grow lights in terms of intensity (LEDs seem to be less bright than T5 HO, but I've read that they have a higher intensity); everywhere, there is so much conflicting info.
Light intensity is measured in lumens. Any light worth their buck is going to list the light intensity.
I don't know how to compare T5 HO to LEDs with all their combined properties and measurements (wavelength, PPFD/PAR, lumens, watts, etc.) in such a way as to know what would be suitable for my current grow house setup. I know I'd need a PPFD/PAR rating of about 1500 μMol/m²/s to mimic full sun, but all the sellers I've messaged on retail sites simply don't have this information for their products. I'd need a PPFD/PAR meter, but the cheapest ones are hundreds of dollars, which is absolutely ridiculous.
PPFD is a very complicated way of measuring light intensity (or more correctly, energy uptake by plants). Unless you're in a very technical setting or you absolutely must reduce electricity costs, forget about it. Its technicality is also being used by sellers as a buzzword now too. If the seller can't provide details, assume they're using buzzwords and can't back up what they claim.

Instead, use lumens and lux (which is lumens per square metre). You need about 10,000 lux for sun-loving cacti. This is less than peak daylight (which is something like 50,000 lux), but that's fine, because you can supply this 10,000 lux 12 hour per day.

As for wavelength, also forget about it. Don't waste you time and dollars buying "grow light" LEDs or staring at mind-numbing wavelength tables, and instead just pick a light with a CRI of 80 or more. CRI is colour rendering index, and is a measurement of how well a light replicates natural light. 80 or 90 CRI is close enough. You can buy 99+ CRI lights, but they're expensive and not worth it for this purpose.

Watts again doesn't matter. You want enough lumens to get the required lux, and you want a light that has a high lumens per watt (lm/W) figure. Watts is the end figure if you want to know how much the system costs you in electricity, not an input. The higher the lumens per watt, the more efficient the light is. But, high lm/W lights are more expensive. You can get 100 lm/W LED downlights for less than $0.75/watt or $0.75/100 lumens. I would know: I bought a bunch after finding i had too many trays of seedlings for my more expensive LEDs over winter. These cheap lights blow every other light source (including fluros) out of the water, while being much cheaper too.
I've just given up for now: I found my old mini greenhouse frame, made a makeshift covering, put my currently-rooted cacti inside, and left them on the east side of my house. My newly repotted cacti are inside under the grow frame right now, and all the LED light's focus is on my new F. latispinus seedling. Hopefully I can prep it for leaving it in full sun in the greenhouse before the end of June.

If I can successfully grow just a single, healthy F. latispinus plant here in WI, that's good enough for me (it's my favorite species); after over 10 years with little success, I'm tired of babying my other cacti, only to see so many of them kick the bucket. If these ones in the greenhouse survive, great. If they get sunburned, or rot in the winter, that's the breaks.
That is unfortunate.

F latsipinus was the first cactus I bought.

Edit:

This is my setup for my cacti that don't like my Australian winter (overnights of 5C), some things that haven't rooted yet and some seedlings.

Image

The lights are 8w (100 lm/W i.e. 800 lumen) downlights I bought from Bunnings (big Australian hardware chain) for A$33 per 4. The "setup" is actually just a spare shelf in my hallways that's sided with cardboard with kitchen foil glued on and a panel of plywood stuck in the top. It's 400m by 900mm and is getting 17,000 lux, which is probably a lot more than needed.

The only thing missing is the fan I added a few days after this photo that blows air behind the lights and into the shelf which keeps them warm.
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