Growlights Setup

[MasonSebastian]

Hi there. I was wondering which lights are 'OPTIMAL' for growing indoor herbs and flowering plants.

I saw a T5 fluorescent bulb, 14W that can be interconnected up to 6 bulbs. I could probably use 4 using a reflector combining 2 coolwhites and 2 warm whites.

I am currently using 1 15W cool daylight and 1 15w warm white Philips spiral bulb (just hangging 2-4cm above the seedlings, 12hrs / day) no reflectors.
https://www.philips.co.uk/c/Energy-savin ... 70100/prd/

I noticed that my thyme and sweetbasils are thriving using spiral bulbs, they already have 4 leaves each. However, lettuce seedlings still have small leaves in them and they are about 21 days already(it says in the pack that you can harvest it in 35 days under partial sunlight) I have a small growing area probably around 40cm by 60 cm, it is not that big.

So my question is, what bulb is efficient? Should I ditch the spiral (I am planning to add anoter 2x 15w to make it 60w) and switch to T5 (56w) setup? Which one is better?

Thanks.

[TZ -OH6]

Efficiency lies in reflection and color temperature. Mylar is up to 95% reflective, aluminum foil is up to around 80% reflective or a bit higher. White grow room platic is a little better than foil, but most white things let a lot of light penetrate that gets absorbed by the backing so they are not as good as foil.

Curly fluorescents block some of their own light so straight tubes are more efficient. For growth without flowering you want 5,000K or 6000K color temperature. The blue light of higher temperature gets more energy to the chlorophyll. Lower color temp tubes put out more green light light which the plants can't use. If you want to grow flowers under lights I would go with something like the the GE plant and aquarium tubes or mix them with 5000K because they have more of the red spectrum helpful for flowering.

Your watts are probably too little. Minimum standard for seedlings is a total of four 32 watt T8 48" tubes (used to be 40 watt T-12s). So that equals 128 Watts of energy getting to your plants. You have 30 watts with no reflectors, so cut that down to a small fraction that the plants are seeing.


Those are things you can get at Home Depot. You can internet order 105 and 115 Watt curly flourescents. Each is about a foot long and will fit in a regular dome reflector, but cost $20-$25 each. Otherwise you would have to go with something like 55watt T-5 grow lights which take a special fixture AND special ordering.

[MasonSebastian]

Thanks. Very informative. However, I don't have access to mylar sheets (I think it is the one they make balloons out of). Instead, I bought a bright chrome spray paint that I will use on a thin sheet of aluminum sheet to form a triangular reflective panel (Note that aluminum sheets are mainly used for roofing, they are shiny, speckled, but shiny.) A little fine sanding should do the trick and then paint it with bright chrome.

I am keeping the spiral CFLs and instead going to add 2 more of 30w (1 each of cool white and warm white) to make it atleast 90w. I have already computed the consumption of 90w on a 12 hr basis for a month, and anything above 100w will put everything off the charts. I am mainly growing herbs for my cooking.

[MasonSebastian]

I went to the hardware and found out about Philips 13W LED. It costs around $18 (Php800). Expensive, yes, but it is actually equals to the power of 85W CFLs (Too bright for a 13w, and pretty cool to the touch too!). I am really amazed by this. I'd probably add 2 of these (1 cw, 1 ww) and build a mirrored louver type fixture.

Do you think 2 13w will be enough to cover a square foot of growing area?

[TZ -OH6]

If they equal the output of 1 85 watt cfl they should be more than enough. Compare whatever you do you do to a standard settup of 4x48" T-8 @ 32 watt over a four foot by two foot table a few inches above the top leaf. So that would be 128 watts over eight square feet.

Reflection doesn't have to be only over top of the bulbs. I surround my whole grow area to make a reflective box. Most of that is make-shift using foil and white plastic covers from plastic sweater boxes.

[MasonSebastian]

Thanks man! I revised my design and opted for t5 bulbs to build atleast 112w for a 2x2 area. I think LEDs are a marketing gimmick IMO.

[mattie g]

Thanks man! I revised my design and opted for t5 bulbs to build atleast 112w for a 2x2 area. I think LEDs are a marketing gimmick IMO.

I highly doubt it. I can't see arguing with the science behind the ability to specifically modify LED output for just the right colors, intensity, and wavelengths to enhance growth. LEDs also use less energy and last a long time, so it's a "greener" and less expensive option in the long run.

If/when I start growing directly from seed, I'm going to go the LED route. But, to each their own...

[brinboise]

However, I don't have access to mylar sheets (I think it is the one they make balloons out of).

A good source for Mylar are those emergency "space blankets". You can find them most everywhere and are pretty cheap ($2-$4) compared to buying mylar in sheets/strips/rolls.

[MasonSebastian]

Hi there. I am almost 75% on my project. I already have the DIY tin reflector but I am still in between choosing flat white or bright chrome. Which one is better? The bright chrome one looks like a silver reflector (not really chrome though) but it reflects so much light, where as flat white is, uh, flat.

Btw, my basil are a bit crazy growing, by the time I finish this project, they'd be around 6 inches with full leaves.