fluorescent grow lights

[dcarch]

I see many heated discussion regarding this topic. There is no need to if we identify all the factors in discussion. Many times we are talking about the same things, or arguing about different things.

· Aluminum is one of the best reflectors, including reflecting UV. That's why most optical instruments use alum. for mirrors.

· Most Mylar foil is alum coated plastic.

· Kitchen foil is alum, very good material to use, one side is more diffusing than the other.

· White is not better than mirror. Depends. The belief that mirror will focus light too much and burn leaves is not true. Most light source is too random to let this to happen.

· Mirror will not create too much shadowing in actual use.

· The perception that mirror is not as good as white is incorrect. White looks very bright, that's not good, because the light is not all going to the plants. On the other hand, mirror makes the walls look very dark, because it reflects all the light down on the plants.

· Be careful using foam boards to surround your growing area. It retains a lot of heat, which can be good or very bad.


My setup which I have been using for a few years, I use mirror Mylar with Velcro attachments. It takes a few minutes to setup and remove. The whole setup stores away in a small box. You will notice how dark the walls appear to the eye because most of the light is reflected down to the plants. You will notice the lack of shadows or hot spots.
dcarch

top view


With the front up. (Light is reflection from the camera's flash.)


with front removed

[ddsack]

Very interesting. I've used a few pieces of aluminum foil to boost darker corners when the plants start to outgrow their alotted area.

Is there a brand name by which your sheets of mirror mylar can be requested? What are they used for in the building industry? Do you buy them in pre-cut sheets, or do they come off a big roll cut to order? I assume places like Home Depot would carry the stuff? Price estimate?

I could see having two sides of my light stand with the reflector sheets, but since I run a fan for seedling ventilation, would need to leave ends open for a cross draft.

[neoguy]

The mylar I buy is the inexpensive emergency blankets sold in camping or sporting goods departments. One brand name I can think of is Coleman, they sell for about 2 bucks and are about 4'x8'.

[amideutch]

Most online hydroponic stores sell it. Also do a search on ebay and they have it there. Ami
http://www.specialty-lights.com/730015.html

[dcarch]

Originally Posted by neoguy

The mylar I buy is the inexpensive emergency blankets sold in camping or sporting goods departments. One brand name I can think of is Coleman, they sell for about 2 bucks and are about 4'x8'.

Many of the so called "space survival blankets" are designed to reflect mostly heat (infra red) and not full spectrum light. They are not very good for plants.

I got my mirror Mylar on eBay cheap. It was a few years ago. I forgot how much.

Again, Velcro makes it very easy to stretch, hang and remove and store away.

Kitchen alum foil makes excellent reflector. You can easily mount it using canned spray-on adhesive on cardboards

dcarch

[ddsack]

Thanks for the info, guys!

At $25 for 48" x 25 Ft. for the low end kind, that seems reasonable from the website. Now that I know about this stuff, I can think of all kinds of uses for indoor and greenhouse use.

[burk4]

Thanks for the website - I'll check it out. I only use my bulbs once a year for about a month.

[Gerald51]

I wonder if the compact fluorescent light bulbs would work?

[dcarch]

Originally Posted by Gerald51

I wonder if the compact fluorescent light bulbs would work?

Yes, CFL works, except they are not as efficient. High wattage CFL are expensive, and they last about 8,000 hours. Tubes last 20,000 hours.

dcarch

[Jackster]

Wondering which are the best types? I believe the higher the color temperature, the closer to daylight they're supposed to be?

I got some of these: Philips 4 Ft. F40 T12 Spectrum Lamp, 40 Watt Daylight Deluxe Fluorescent Bulb (2-Pack)

specs:

• Bulb Type : Fluorescent
• Color / Finish : Daylight Deluxe
• Color Temperature : 6500
• Commercial/Residential : Residential
• Energy Star Compliant : No
• Indoor or Outdoor : Indoor
• Life : 20000 Hr.
• Lumens : 2325
• Maximum Wattage Per Bulb : 40Watts
• Color Rendering Index : 84 CRI

thanks!

Jackster

[amideutch]

Jackster, for growing seedlings those tubes will do just fine. Ami

[amideutch]

Just got done with my seedling light I made out of a ceiling fluorescent fixture I snagged from work when they replaced all our lights. It's got 3 ea. Vita-Lite's power twist 40 watt at 5500k.
6 ea. 26 watt CFLs at 6400k. Here's some photo's. Ami

[lumierefrere]

So going with the tubes you can buy in WalMart or Lowe's--which ones are optimal? is there benefit to getting the actual GE plant lights you find there (as opposed to the ones that cost $100)?

[Jackster]

Originally Posted by lumierefrere

So going with the tubes you can buy in WalMart or Lowe's--which ones are optimal? is there benefit to getting the actual GE plant lights you find there (as opposed to the ones that cost $100)?

I had the fixtures already, and they had old tubes in them. I read one of the old posts that stated older tubes lose their efficiency over time, so went to Home Depot to look for new ones. I picked out the ones they had there that were closest to daylight (according to the chart they had). These were in a package of 10, and were 2.00 per tube. Not sure if the GE plant lights are much better if you're trying to grow seedlings which is what my goal is.

Last year I only had a tray in the window, and they got really leggy, so trying the lights this year

Jackster

[dice]

I read somewhere decades ago that Cool White spectrum is good enough for seed starting, that you do not need the
additional red spectrum in the warm white, daylight bulbs,
and grow bulbs until plants start to flower.

This article on lighting for seed starting at Dave's Garden
( http://davesgarden.com/guides/articles/view/464/ )
says:

Seedlings don’t need full spectrum lights; the cool fluorescent tubes in a cheap shop light are fine.

Edit:
Cool white and warm white bulbs usually cost the same, so I tend to
put one of each in a 2-bulb, 4' fixture. When the bulbs have a few
thousand hours on them and I change them out for new ones, I may
prefer the warm white bulbs in some fixture where I reuse the old ones.
"Daylight" or "full spectrum" bulbs may be better if they cost no more
and last just as long, but the spectrum on any 4' flourescent bulb that
you find at a big box store is good enough for seedlings.