[laughingwillow]

Then I'm guessing MH is the way to go for optimal results. HPS is considered a supplimental light in most horticultural circles.

lw

[EA-1306]

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.

[laughingwillow]

I thought we were all talking from personal experience here. Guess I was wrong, eh?

lw

[EA-1306]

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?

[laughingwillow]

I've had far better results using mh to vegetate plants than hsp. No contest, imo. Especially for long-term applications.

lw

[laughingwillow]

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

[EA-1306]

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.

[laughingwillow]

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

[EA-1306]

LW, what are your sizes after 18 months?

[laughingwillow]

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

[EA-1306]

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.

[Green2Herman]

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?

[EA-1306]

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?

[anti-light]

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.....

[Cyano]

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?