MH, I'd guess.
HPS runs through mainly the red spectrum, MH the blue. HPS does a good job recreating end of the year light, conducive for flowering. MH is a broader spectrum that promotes vegetative growth.
lw
I'm afraid you would prolly have the best luck using the MH lights as a suppliment to natural. To grow by artificial light only and maintain normal growth may not be possible. But I would prolly start experimenting in the 100-200 watt per square foot range under the assumption that it may well take more than that. Keep in mind bulb lifespan will come into play at least a couple times a year. I'm guessing one could prolly get by with 12 hours of light/cycle, as most cactus of interest have evolved fairly close to the equator under similar natural conditions.
Keep us posted as to progress, eh?
lw
You can buy one type and convert to the other with a kit.
Go to the littlegreenhouse.com on the web to find conversion kits and even combo light kits, which will allow you to run 1 of each individually or simultaenously.
Edited: Didn't mean to create a direct link.
Conversion bulbs generally are less efficient than regular issue, unless there is an inexpensive way to actually create a switchable ballast allowing for the use of standard bulbs of either variety.
windey: Are the powers-who-be allowing hot links to vendors now?
lw
LW: You are correct to ask, and I am uncertain.
Edit to be made.
Edit: Edit of prior post made.
HPS are very effective for growing cacti indoors.
HPS work great. Just dont put them to close to fast or they get black burning.
San Pedro you can give water twice a week if you keep them under HPS. In this case they tend to grow very fast. Some more blue side light like some fluorescent lamps.
I havent tried growing cactii under MH, but that probably works good also. I dont really think it differ much.
Roach, whether you go with HPS or MH, I'd go MH as its more for veg. growth, but either way get a bulb in the 400MH or 430HPS range the smaller ones aren't that great and the larger ones would be overkill.
I use 2 150 W HPS, and they give me very good results.
.....Right on, crow. 400's are easier and cheaper to come by than 430's. And the cost/lumen payoff is definitely worth considering. Units between 400 and 600 watts are said to be the most cost effective choices, from what I've read.
lw
shit... i found that a 70w hps works great as cacti over wintering light.... and to start seeds.... and veg sickly cacti.... dry em out if needed.....
the mh is better for all round though...... ive always been a fan of the cool spectrum mesophylls (chloro like sugars)
but im thinking the hps will work fine....the cacti will adjust themselves over time
going back and forth.... inside then outside and vice versa.... will probably make em grow slower though...
take care yall
Quote from: "laughingwillow".....Right on, crow. 400's are easier and cheaper to come by than 430's. And the cost/lumen payoff is definitely worth considering. Units between 400 and 600 watts are said to be the most cost effective choices, from what I've read.
lw
I have read that too.
150W HPS are just so readily available, a 600W HPS with a horticultural bulb would be the way to go IMO.
From what I have read horticultural HPS give better results that MH or even horticultural MH.
I dont think the differance are as big as for example growing very green and fast growing herb (like the famous one). Although maybe the sun in the desert are close to the HPS.
The sun in the deserts are closer to the MH spectrum than HPS. The red spectrum of the HPS simulates the light conditions of late fall.
If you want to pay the price for a full spectrum HPS, that's prolly the way to go. Of course, you are prolly looking at $75/bulb or more.
lw
Results speak louder than solar approximation. Much of the solar spectrum is not used by plants. The idea is not to imitate nature, but to provide optimum conditions.
Then I'm guessing MH is the way to go for optimal results. HPS is considered a supplimental light in most horticultural circles.
lw
MH is used as supplementary lighting as well, HPS is used because it is more efficient.
Many reviews of horticultural HPS lamps mention they outperform the MH.
I thought we were all talking from personal experience here. Guess I was wrong, eh?
lw
I have had better results using HPS that any full spectrum lighting.
Also reviews and product trials are someone's personal experience are they not?
Why should we disregard them?
I've had far better results using mh to vegetate plants than hsp. No contest, imo. Especially for long-term applications.
lw
ea: Just how many cactus are you sustaining with 2 150 watt bulbs? Am I correct in assuming that you are running them indoors through the summer as well?
lw
I only grow seedlings under the bulbs, about 200 right now. I also root under them.
My cacti respond better to the HPS, but other plants respond better to full spectrum lighting. It depends on the species. Some cacti don't do as well too, like Pereskiopsis seems to prefer full spectrum lighting, however my T andalgalensis X T pachanoi hybrids do better under the HPS than outdoors.
Roach wants to grow adult plants under lights all year long.
I put seedlings under flouros and then begin to acclimate to the sun during their second summer.
lw
LW, what are your sizes after 18 months?
I put a tray of various trichos (mostly tershekii) and lobivida's out this spring. They have been under a rose bush in partial shade. The tershekiis are finally taking off. Some are reaching thumb nail size. I'm in no rush. I'll prolly transplant in the fall. I've lost many lobividas and have no idea why.
lw
Yeah those terscheckii take their sweet time.
I am not in a hurry or I would graft, but I do have pretty good rates of growth.
Quote from: "laughingwillow"The sun in the deserts are closer to the MH spectrum than HPS. The red spectrum of the HPS simulates the light conditions of late fall.
If you want to pay the price for a full spectrum HPS, that's prolly the way to go. Of course, you are prolly looking at $75/bulb or more.
lw
Do that include the light that mirrors up from the ground?
Very interesting question!
Solar spectrum is not PAR, (photosynthetically active radiation) and the PAR values for the cacti have many specific factors.
Park S Nobel has some great work on this that shows that size, surface to mass ratios, plant position, rib structure, and spination all affect PAR received, and no doubt the reflection from the ground affects this as well.
How this would relate to artificial and supplemental lighting is a complex topic and seems to be an area that little research has been done in. Perhaps Nobel's work can be used as a starting point?
the proofs in the pudding.......
both will work fine......
im thinking that the plant will get adjusted regardless......
i noticed that bringing a plant inside under lights....
and then outside.... actually stunts growth..... just moving them..
so im thinking... that once it sits for a while....they will do just fine.....
I also want to grow cacti indoors under artificial light all year around. Does someone know how many cacti (Pedros) in what size of plantcontainers per square meter produces the largest yield?
Since installation of the 1000 Watt metal halide, the Hoodia I have from Stonehenge is very happy.
This winter, some cacti will go indoors under the light while others rest indoors in a cool, dry place. They will be on a 2-month shift, half resting and half growing under the light. This way I shouldn't have to threaten any with the cold and damp garage that rotted two cacti last year - totem pole aka Lophocereus schottii mostrose and the tetra-pupping Mytrillocactus geometrizans.
The other advantage about the light is that I will get to see sooner if the new potting mix is really worth all I hear about it.
A blend of porous yet hard granular material called Turface and coconut coir. This is supposed to set easily, but drain well too so the roots don't soak and so they get plenty of air. I am thrilled to try this and get rid of the sandy crap I made.
winder... would you explain what your crappy sand mixture consists of?
out of curiosity
Sand that packed densely with the compost I had mixed with it, maybe 4 parts sand to 1 part compost. The sand was fine and did not wet well and did not drain well. Water would puddle on top and slowly seep through. The roots were all clustered against the wall of the terra cotta pots.
In the more open mixes I have seen, the roots form a network through the mix and the mix drains quickly.
hum....ive been playing with a high mineral mix... for somethings atleast...
pumice stone crushed up.... perlite.... sand... gypsum....compost
it dries out pretty fast i think..... and it does compact.... but i find it breaks up somewhat....once dry.....
i know that cheap sand will make a cement like soil.....
peace