Grow Lights

[Ralph D.]

So... as a carry over from the other thread...

Another thing the agent thought was that I had made a mistake in swithching to all grow lights. Says that they are not full spectrum and suggested adding a few regular flourescent lights. I have 5 shelves with 4 'Grow Stick' flourescent lights. If I were to place a small lamp on the top shelf and another on the middle shelf with those newer screw in type flourexcent bulbs meant to replace traditional bulbs at 26Watts each (maybe three lamps?) would this add a sufficient amount of the missing light? I have no convenient way of getting them to a good window and start waaaaaayyyyyyyyyyy too many seeds for window sills (not to mention old aluminum frames transmit the cold at night and there would be a PIA ritual of taking everything down and putting it back up again in the AM).

Anybody know anything about light spectrums as it would relate to growing seeds?

[zxcvbob]

My seedlings love the spectrum from cheap triphosphor lamps. They also like fluorescent grow lamps, but those are expensive and they fade -- and you will keep using them long after they are worn out because you can't really see how bright they are because your eye doesn't like that spectrum very much.

If you have room for 4-foot flixture, I recommend getting a cheap commercial 3-lamp F32T8 fixure with electronic ballast. The kind used for suspended ceilings are good. Use something like Philips ALTO 830 or

835 lamps, or GE SPX35's. The lamps are really cheap ($2 each), and they maintain 90% of their luminence throughout their 20000+ hours life, unlike old-fashioned F40T12 lamps that drop off much more quickly.

The ALTO lamps with the green endcaps are very low (but not 0) mercury, for what it's worth.

Best regards, Bob

[dps]

You will get varying opinions on grow lights. When I used to use lights to start plants I did not use them. Used regular fluorescents (they were cheaper). They worked OK but not great. I packed the light fixtures in as close as I could to get the most light concentrated onto the plants. I tried grow lights on one shelf and saw no difference. It was a very limited and non-scientific experiment. If there's no difference between grow lights and the regular fluorescents, you might not want to spend a lot of money on the extra lamps. However, you have to make that decision yourself, so I would suggest you do your own experiment and get a lamp or two and put it at one end of your tray. If that end does better than the other then you will know that it's worth it for next year.

I had a lot of space under the lamps, so I took a pile of newspaper and placed the flats on it so that they were 1-2" from the lights. As the plants grew I removed layers of newspaper so that they didn't grow into the lights, but stayed close to them for maximum light. It was a lot easier than trying to move the light fixtures.

The newspaper also helped to absorb water that I (invariably) spilled.

I now have a greenhouse and it's much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much much easier.

Ralph D. wrote:

[Jeana]

The first year I started seeds we bought "grow lights." After that I read they weren't really necessary for starting seeds. I just bought plain old shop lights and hung them from the rafters with chain. I never noticed a difference in the growth of the plants. There might have been, I just didn't notice it. They worked fine. When I didn't have enough chain I used old books, mags, bricks, anything works.

If we had really cold weather and the furnace was running I had a better germination rate. I never bother with heating cables because I don't want to spend the money on them. If I think the seed trays need warmth I put them up on top of my kitchen cabinets, or anywhere else in the house that gets warm.

You might want to use a fan for good air circulation. I learned the hard way. ;)

Jean Zone 5 OH reply to newsgroup only

[Timothy]

Seeds require little light (or no light) to germinate. Heat is generally more important for germination.

Lights in a nutshell... I worked at a factory greenhouse (Smith gardens slave factory) and while there I was working with the light guys. I've played with a lot of commercial lighting systems over time and light specturm was talked about alot. Lighting systems break down to three types: High pressure sodium, metal halide and fluorescent.

High pressure sodium or HPS systems produce an orange/red colored light. These are most commonly seen in use as street lights. The light spectrum produced is red-far red as plants are concerned. This is the better light spectrum for producing flowers and fruits.

Metal Halide systems are the most efficient 'white' light producing light known to man. These are most commonly seen in warehouses and stores. These lights produce a blue-blue white spectrum that work best for folage plants or non-blooming/non-fruiting plants.

Fluorescent systems varied as far as their out puts and spectums. The cool white/ shop light types produce a blue spectrum, while the kitchen and bath lights produce a red/ red'ish spectrum. For starting seeds or vegetating plants, a blue light should be just fine. To help encourage those little african violets to bloom, a deeper red spectrum light would be used. I tend to cheat and encourage my clients who use their lights for seeding and growing to mix the lights. A cool white and a kitchen and bath in the same light fixture will produce a near full spectrum, generally at a cheaper cost to the full spectrum plant lights.

A word to the wise..., mercury vapor lights do not produce a useable light to plants. The light produced is too far into the blue spectrum and the majority of the light engery is just plain wasted. If you find yourself using lights more often than not for your house plants and garden plants, it's well worth the money to purchase a metal halide or hps light fixture.

Happy gardening .

[zxcvbob]

Triphosphor fluorescent lamps and metal halide lamps are both about equal in light efficiency, approaching and sometimes exceeding the magic

100 lumen/watt number -- *BUT* metal halide lamps do not maintain their luminosity nearly as well as modern fluorescents. Metal halide also do not provide nearly as good color rendering nor "full spectrum" as fluorescents.

Metal halide lamps excel at providing lots of pretty good white light in a small package at much higher efficiency than equivalent incandescent lighting. For bright diffuse lighting, fluorescent beats MH hands down and is cheaper -- but you need to use better fluorescent lighting than your typical "shop light".

Best regards, Bob

[John Thomas]

For what it's worth, Scientific American had an amateur scientist column c. 1969, since reprinted in collection of the columns, on what sort of lights work best with seedlings and mature plants.

I found the book at my local library.

[Stephen Henning]

I have been taught by the experts that the "gro-lites" are a waste of money. The best grow lights are a mixture of cool white and warm white fluorescent tubes. On a 2 tube fixture, use one of each. On a 4 tube fixture, alternate with 2 of each. This combination the highest lumens per watt and spans the optical spectrum best.

[zxcvbob]

That information was correct 30 years ago. The EPA ruined 40W fluorescent cool-white and warm-white lamps back in 1974, IIRC. But even back in the 70's, cool-white and warm-white lamps did not maintain their luminocity very well, and you had to change the lamps every year or two to get good plant growth with them.

If you want good lighting today, you use GE SPX series lamps, or Philips or Osram "ALTO" 800 series lamps. The lamps are cheap, they have a very good spectrum, and they maintain typically 90% of their luminence for

20000+ hours.

Regards, Bob

[William Brown]

Armed with a copy of this thread, I headed for Home Depot.

They had no three bulb fixtures, so I splurged and got a 4 bulb, but it wasn't cheap.

I then headed for the bulb section. They had a lot of Phillips and a few GE bulbs, but none of them was marked 830 or 835 or SPX35. The clerk was typically clueless, so I got some Phillips ALTO 40 watt cool white plus bulbs, 3200 lumens, 20,000 hours, 70 color rendering, and

4100K color temperature. Buried beside the dimension is the marking T12. Since I had space for 4 bulbs, I installed two of the new ones (very bright) and two grow lights I had from last year (they looked almost dim next to the new bulbs).

I have no idea if these are the recommended bulbs, but its too late now, the pansies and snaps have been sown.

Incidentally, some years ago we had a fluorescent light fixture in the bathroom and I put a spare grow light in there, thinking I might grow some hair. It didn't grow hair, but gave a much more pleasant light in the room; colors seemed darker and brighter, at least to the naked eye.

[Jack Allen]

I went looking for these lights today and couldn't find them anywhere.