Grow Lights for Propagating Fig Cuttings

[AscPete]

There is relatively little available info on propagating fig stem cuttings with artificial lighting, (6), (7), (8), (9). Most of the fig forum members that have shared their experiences and success have used florescent lighting. I typically prefer to use natural sunlight from south facing windows, but will not have that option due to planned propagation of over 100 cuttings for local bartering. I've opted to dust off my seed starting rack (10) and 4' florescent fixtures to start the cuttings early, this winter. Searching for bulbs and possible T12 fixture upgrades resulted in some reassuring info on bulb selection but conflicting info on fixture selection and operating costs.

There are a couple common misconceptions about growing plants indoors with artificial lighting, but growing plants under lights indoors doesn’t have to be a technical or expensive endeavor. The first common misconception is that special and expensive light bulbs are required for growing indoors. The truth is you do not need special or expensive lighting. A common 4 foot T8 shop light fixture can be purchased from your local hardware or home improvement shop for about $20, and will be suitable for growing small plants.

The bulb also does not have to be special. However, it does need to be selected carefully from all the options you will have at the hardware shop. Many fluorescent T8 light bulbs won’t do much for your plants. Plants use blue wavelengths of light for green growth and red wavelengths for flowering. Without getting too technical, red is at the bottom of the light spectrum, and blue is at the top end. Light bulbs have a light/color spectrum rated in Kelvin. Most light bulbs in the hardware shop will have a ‘cool white’ output in the middle of the spectrum at 3500k to 4100k, but what you need for healthy plants is at the higher and lower ends of the spectrum. Look at the bulb packages and find a 6500K bulb. This will provide the full light spectrum, including blue light that plants need. Common T8 Light fixtures hold 2 to 4 bulbs, so if you are interested in getting your plants to flower you can use a bulb with a K rating of 3000 or less, in conjunction with a 6500k bulb.

This brings us to the final misconception on costs. A two bulb T8 shop light fixture costs 20 dollars, and a two pack of T8 fluorescent light bulbs costs less than 8 dollars. The total equipment cost for a small growing space is about 28 dollars. Get fancy and add a mechanical timer for 4 bucks, and you have yourself an automated system. So what about the electrical bill? Your electrical bill is not going to sky rocket. A rough estimate of the operational cost of a two bulb T8 light fixture, running 16 hours a day, is between 4 and 8 dollars a month. Annually that’s a cost of no less than 48 dollars, and no more than 96 dollars per year. Your actual cost will be based on your kilowatt/hr rate, which you can find in your electrical bill. (1)

There's also been perpetuated misinformation of the operating costs for T5 lights and fixtures compared to T8 and the older now obsolete T12. http://image.slidesharecdn.com/energ...?cb=1358288164 , http://t5lightingusa.com/site/galler...t12-lights.jpg . The comparative costs are skewed in favor of the T5 lights due to doubling the quantity and wattage of T8 and T12 lights (in the comparison tables), the actual cost savings between T5, T8 and T12 lights are much less when actual Watts and Lumens are also compared. The cost to operate 4 (28w 2900 lumens ea) T5 bulbs for 16 hrs / day for 3 months @ 0.12 / kWh is $19.35 (20), the cost for 4 (32w 2950 lumens ea) T8 bulbs would be $22.12 (or 14.3% more) and four T12's (40w 2325 lumens ea) would cost $27.65 (or 42.9% more). T8 shop lights and bulbs are readily available, and are (much) less expensive to purchase than T5 fixtures and bulbs.

The T8 light fixtures and bulbs are actually more efficient and less costly to operate than T5's when used for these grow light applications. In actual use T8 fixtures are more efficient and produce more light for consumed watts (Lumens per Watt) at normal ambient room temperatures (77 deg F), (21) than standard T5 bulbs which reach their peak efficiency at warmer ambient temperatures (95 deg F), they even outperform the popular T5 High Output (T5HO) bulbs and fixtures, (13).

Fluorescent bulbs come in varying wattages, and spectrums. Ultimately, you would like to use the highest output, fullest-spectrum bulbs that you can find. When a plant is growing, it not only requires enough light, but that light should be rich in both ends of the light spectrum. There are two definitive stages in a plant's growth and they are the vegetative and flowering stages. The initial stage is vegetative. This is where the plant performs most of its vertical growth, and strengthens the main stalk. The flowering stage takes over as the plant begins to get "busy" and starts to produce its flowers. When a plant is in its vegetative state, it focuses its thirst mainly on the blue-violet end of the spectrum. When it is flowering it focuses on the red-orange end. Ultimately, you would want to incorporate a 40 watt full-spectrum tube. This would provide you with the greatest results.

These tubes produce 68 lumens per watt, for a total of 2750 lumens. Fluorescents are ideal for initial propagation because they produce almost no reciprocal heat. You can hang a four tube fixture six to eight inches above your plant canopy, and then just keep raising it as your plants grow, without fear of burning your leaves.

In this example, we will scale down the size of our test garden. Earlier, we have been using a five feet by five feet garden as a reference point. For this example, we will use a two feet by four feet garden. A two feet by four feet fixture can hold four bulbs. This will give us a total of 11,000 lumens (4 bulbs multiplied by 2750 individual lumens = 11,000 lumens). Allowing for "spilled" light, we are probably generating about 1031.25 F.C. (11,000 lumens multiplied by 75% = 8250 lumens...8250 lumens divided by eight square feet = 1031.25 Foot Candles). This is assuming that the lights are placed DIRECTLY over your plants. As you raise your lighting, your light intensity drastically drops. When you double the distance between your light and your plants, you cut the light intensity by four times.

As I mentioned earlier, fluorescents are ideal for initial propagation. They provide a good supply of full spectrum light for your seedlings or cuttings, without fear of burning them when they are at this fragile stage. A two feet by four feet area can support up to 400 plants. Because of this, even though fluorescents are adequate for the full life-cycle of a plant, most indoor gardeners use them as an initial propagation area, then move the plants to another area as they begin to mature. (2)

Inexpensive T8 florescent shop light fixtures and standard florescent bulbs, 6500K "Daylight" and possibly 3000K "Warm White" can be used for propagating fig cuttings indoors to promote healthy vegetative growth.

References:
1. http://www.gardenisto.com/systems/li...-light-basics/
2. http://www.simplyhydro.com/why_hydro.htm
3. http://www.gardening.cornell.edu/hou...ardening81.pdf
4. http://www.gardenisto.com/systems/li...-light-basics/
5. http://extension.missouri.edu/explor...ort/g06515.pdf
6. http://figs4funforum.websitetoolbox....84&postcount=4
7. http://figs4funforum.websitetoolbox.com/post?id=6532491
8. http://figs4funforum.websitetoolbox.com/post?id=6724415
9. http://figs4funforum.websitetoolbox....6&postcount=20
10. http://www2.arkansas.net/~mgee/growl...ightstand.html
11. http://www.gardening.cornell.edu/fac...ite/index.html
12. http://www.threefoldfarm.org/blog/si...ig-propagation
13. http://www.lrc.rpi.edu/programs/nlpi...s/lat5/pc7.asp
14. http://www.lrc.rpi.edu/programs/nlpi...advantages.asp
15. http://www.lrc.rpi.edu/programs/nlpi...omparisons.asp
16. http://www.lrc.rpi.edu/programs/nlpi...ghtSources.asp
17. http://kindledgrowlights.com/spectrum-par-reading/
18. http://www.bmlhorticulture.com/photosynthesis-guide/
19. http://www.salsburg.com/lightcolor/lightcolor.html
20. Formula to calculate kW costs... (4 x 28 x 16 x 90 / 1000 x 0.12) = cost for 90 days.
21. http://www.ourfigs.com/filedata/fetch?photoid=50096
...

[don_sanders]

I went for the T8 option with 6500k bulbs by east and west windows myself. Seems to work well. My electric is only $.069 / kwh so I calculated it out to about $2.12/mo for each strip of 2 bulbs @ 16hrs/day. My fixtures were somewhere between $15-20 and the bulbs were about $3.50 each.

I also like that they aren't hot enough to burn most leaves if I don't happen to notice the plants growing up into the lights before they touch them.

I thought about the T5s but the additional fixture and bulb cost deterred me. Maybe someday I'll switch to them or LED once the prices drop.

[AscPete]

Thanks for commenting and sharing your experience.
I purchased a 2 bulb T8 shop lite and a 2pack of 6500K bulbs at W*mart all for $20.00 including tax. I'd considered using the shop lite for the upgrade parts but will order new T8 ballasts instead, the older fixtures are T12 light troffers.

[smithmal]

I'd like add a UV light into my fluorescent growth shelf. One shelf (4' x 2') contains 3x two bulb shop lights. Presently each shop life contains 2x 6500k T8 bulbs.

Lots of evidence around the net that UV bulbs reduce mold and fungi. I'm thinking since I have my shop lights so near the surface of my cuttings/plants, I'd need one bulb per shop light to get equal exposure across the entire shelf. Also, it's my understanding is the Germicidal UV bulbs (280nm - 200nm) use UV-C light. Germicidal UV bulbs tend to come in a variety of wattage.

Any thoughts on what wattage I should go for with my setup?

Malcolm

[AscPete]

I have no info on UV bulbs or lights...

[Jamie0507]

Malcolm Id be very interested in hearing about whatever you learn on this topic in the future.. Very interesting topic!

[Harborseal]

You would have to wear UV eliminating glasses and be sure no one can see any reflected light. UV causes cataracts.

[smithmal]

Harborseal,

Your absolutely right about that UV-C has a potential to damage eye tissue (cornea).

From what I've read, the amount of UV-C light necessary to reduce/eliminate fungal spores on plant/soil surfaces is very little. Depending on the wattage of the UV-C bulb and the distance from the cuttings/plants, you'd probably only need to pulse expose the plants for 10 seconds - 30 seconds per day. From my experience growing cuttings in high humidity environments, damage from fungal growth is at its worst early during the initial rooting of cuttings because of the need for high humidity which promotes fungal growth. For this reason, once you acclimate the plants to ambient humidity later on, the need for UV-C to combat fungal growth may no longer be necessary. That being said there are studies that suggest exposing plants to UV-C routinely causes them to biochemically boost natural plant defenses again many plant pathogens.

Also, I've read that it's a good idea to have a 4 hour dark period after UV exposure to allow plants to bounce back from the exposure. For this reason, I'd probably set up two timers. One for the fluorescent light (on/off to give 15 hours of light per day) and one for the UV light (on/off to give 10-30 seconds of light right after the fluorescent light cycle is over).

Someone has already figured out the calculation to determine exposure time when taking into account UV-C wattage vs. distance from cutting (I just need to find it again).

So the final question is coming up with a suitable lighting arrangement. I suppose you could intersperse a couple single bulb light fixtures within the shop light fixtures and have both types of fixtures on separate timers.

[AscPete]

Malcolm,
Is the UV-C light to be used in the Pre-rooting stages, where light is not usually required or necessary?

Maintaining a "clean" Pre-rooting environment and reducing the pH will reduce and almost eliminate fungal growth. There is very little damage caused by fungal growth on the soil surface. There are also many simple remedies and precautions that can be taken to avoid soil surface fungal growth, keeping the surface dry or adding a dry fast draining topping or an anti fugal dust or spray can keep the surface dry and or eliminate any fungus.

The major damage to cuttings is rot usually caused by soil microbes below the surface of overly damp/wet mediums and some solutions to those microbes are discussed in this document, http://tomclothier.hort.net/page13.html

[smithmal]

Pete,

The UV-C light would be strictly for used for its germicidal properties rather than plant photosynthesis. I grow my cuttings in my basement and for some reason I have a devil of a time dealing with fungal spores especially when propagating cuttings in a high humidity environment. That's after rinsing cuttings in bleach as well as the cups I use to grow the cuttings in. That being said, the idea of adding a 1/2" of so of sand to the top of the soil seems like a really easy fix. Do you think that would help out? I tend to see more fungal growth on the cutting surface though (specifically around the node areas rather then around the soil).

[AscPete]

Malcolm,

What potting mix are you using?
How wet is the potting mix?
Do you know the pH of your water and resulting wet potting mix?
What are the temperatures of the mix inside the cups?

The exposed cold copper plumbing in your basement is actually decreasing the humidity by condensing it into water, but may provide wet areas for mold growth. The temperature of the basement is much more critical to the growth of the cuttings. Condensation on the sides of the cups is mainly an indication of temperature difference on either side of the surface, moisture will condense on colder surfaces.

I've pre-rooted hundreds of cuttings successfully in seedling trays in sterile seed starting mix and coir mix with humidity domes and have had to 'knock back' white mold on cuttings only a few times with a 25% spray of 3% Hydrogen Peroxide (1 part peroxide / 3 parts water),
http://figs4funforum.websitetoolbox....5&postcount=57 The sealed trays were placed in a dark closet with a maintained temperature of approximately 75F. for approx. 2 to 3 weeks or until rooted.

[smithmal]

Pete,

Thanks for taking the time to answer my questions.

Potting mix is:
ProMix-MX with 30% perlite

Water is:
Well water pH around 6.8

Basement temps are:
Probably range between 60-70C as I have a boiler in my basement

[AscPete]

I don't know the MX designation, if the Pro-mix has Mycorrhizae it could be the source of your fungus (beneficial microbes).

One way to get ahead of the mold problem is to start the actual rooting with inert mix / rooting medium temperatures at 72F - 78F which will get the roots growing quickly. The potted cuttings ambient temperatures / humidity can then be reduced to the cooler growing temperatures without the domes.

I use a heated space (closet) with temperatures above 72F, IMO its the simplest way to perform this procedure, but heating mats with thermostatic controllers is usually recommended. Also burying most of the cuttings' surface below soil line will help to reduce fungal growth and maintain the necessary 'humidity' / moisture that the cutting requires for hydration. Good luck.

[Brian M]

I know this is slightly off subject but how much do you think a 1500 watt space heater would cost monthly?

[AscPete]

You can calculate your estimated usage and cost... http://www.wikihow.com/Sample/Kilowatt-Hours-Calculator

[Brian M]

Thanks!

[ross]

I'm using LED bulbs, which are burning some of the leaves of my cuttings. Unfortunately, my setup isn't ideal, and I can't raise the fixture any higher. Lowering the fixture for fluorescent bulbs isn't ideal either because the fixture won't cover the entire space. Will decreasing the amount of hours I leave the fixture on solve my problem?

[Bluemalibu]

Ross, about half of the current LED lights are dimmable. Check your bulb's packaging for the specifics on its capabilities, and if so, a rheostat can be added to dim the output. Otherwise, all of the building supply stores carry diffuser panels that will lesson the intensity of your lights. http://www.homedepot.com/p/Lithonia-...8-M4/202311103

Sorry... I just noticed that this thread is a year old.

[AscPete]

The recommendations is 16 hours maximum for light with 8 hours minimum dark.
As noted in the links in the OP direct sunlight has ~ 10,000 Foot Candles (lumens / square foot) and "adequate" florescent lighting has ~ 1050 Foot Candles.

With those numbers as your benchmarks;
Are the LED's providing enough light? and Will they provide enough light with their reduced on time?

[COGardener]

Pete,

In your spare time you should look at REEF aquarium variable Kelvin LED's, there is now 400 and 1000 Watt MH equivalents. There are many sites and many brands to look at, they are rather costly yet may be well worth it in the long run.

Of coarse they are available in non reef applications as well.

[F. Bennett]

Great topic. A few years ago I used the t8 4 foot shoplights and had great results. I had the lights within an inch of the top leaves and had no ill effects. Gnats were a different story...

[AscPete]

Thanks.
and thanks for sharing your experiences.

[AscPete]

Scott,
Thanks for sharing that info...
a google search " REEF aquarium variable Kelvin LED " resulted in, http://aquarium-digest.com/tag/best-led-reef-lights/ very informative...

and a manufactured LED that provides the required plant light spectrum, http://www.marinedepot.com/ATI_Siriu...FILDTN-vi.html The X6 model which covers an ~ 24 inch x 48 inch growing area ...

ATI Sirius X6 LED Light Fixture

General Sizing Guideline:
- Recommended Tank Size: Up to 48" x 28".
- Recommended Tank Depth: up to 36" with proper placement of corals.

Product Specifications:
- LED Layout: 6x 75W LED Clusters
- LED Configuration (Per Cluster):

6x Cree XPE Blue
2x Luxeon M Royal Blue 450nm
2x Luxeon M Cool White
2x Cree XPE Red
1x Semileds Violet 420nm

- Dimensions: 39" x 14.2" x 1.6" (L x W x H)
- Weight: 20.7 lbs
- Power Consumption: Up to 435W at full intensity

$1,642.99 , Free Shipping...

[SCfigFanatic]

I built a warm white 200 watt LED for $24 per led (2) for $48
2 fans, $8 resistors $4 thermal paste $5 wiring $5

Building LED lights is quite simple. And not very expensive.
10,240 LUX at plant height. Just tested with 2 different testers.

Doug

[COGardener]

Like I said, expensive!!!! Yet the price is continually coming down as time goes by. 8 years ago a 250w MH equivalent fixture was around $6,000.

[AscPete]

The info on lighting requirements for healthy Coral Reef growth is very interesting and similar (spectrum) for plant growth...

An 'equivalent' 6 bulb T8 fixture from H*Depot with 10 pack of 6500K Daylight bulbs for plant growth for a 24 inch x 48 inch coverage would cost ~$120.00 plus tax.

[COGardener]

On the surface yes. And in totality there are few differences since the goal of lighting a reef is to grow zooxanthellae. Like plants corals live in a never ending array of environments with very specific lighting intensities and requirements. A deep water coral, say around 80' +/-, is adapted to a substantially lower amount of light and a change in Kelvin do to the absorption of light by the water. Whereas a coral in shallow water, 10 of less feet sometimes inches or even exposed at low tide, is adapted to very intense lighting and a Kelvin closer to natural sunlight.

Not to get to wound up in reef keeping, not only is light spectrum and intensity critically important, solar radiation a chemically balanced and properly maintained environment as well. Sound familiar?

[AscPete]

Scott,
I was not comparing the T8 lights and fixtures used as grow lights to the LED lights and fixtures used in the Reef Aquariums!!! That's an apple to seaweed comparison.

I was comparing the amount of equivalent light (Spectrum, Lumens, Foot candles, etc) provided by either fixture for use as a grow light for fig cuttings in the 24 inch x 48 inch growing area, an apple to apple comparison.

[Daniel-PacificNW]

I am new on here and this is the first post I have seen. Very useful and well written post!

Being in the North, we have very short winter days / long nights and the angle of the sun is low so not helpful in windows. I use flourescent lights for starting seeds and cuttings. Mine are shorter, 2 foot kitchen fixtures, to fit in my plant stand. Sometimes I add a couple of fluorescent desk lamps I have sitting around. The straight tube light bulbs are 4,200 K for the 2 foot fixtures. I also have a set up with CFL fixtures. The CFLs are 6,500 k - "day light" - are better for growing than the "bright white" 2,700 k. They work very nicely for cuttings and for starting vegetables and flowers inside in mid to late winter.

I attached photos of my plant lights from feb 2014 with some fig cuttings. The home made CFL plant light system was from some youtube videos, not my invention. The parts altogether cost $31 including the 2 23-watt CFL bulbs. Everything seems to do well with this, fig starts, tomato starts, pepper starts, and currently plum and apricot seedlings.

https://www.youtube.com/watch?feature=player_detailpage&v=Xy5fzPlsXK0

[don_sanders]

Oh, come on. It's free shipping.

Added a calendar entry to check again in ten years.

They are very nice but outside my pay grade.

[don_sanders]

There are definitely some cool LED options and some that seem fairly inexpensive but with a 2 year minimum RTO with even the cheapest options based off of saved power consumption, I'll probably stick with my existing florescent until I have to replace them.

Maybe they'll have more options by then.

[don_sanders]

Oh, and I did see these do it yourself instructions. Almost 60,000 lumens @ almost 600 watts. Could probably do it for a few hundred dollars cheaper with the cheaper Chinese eBay LEDs and drivers.

http://www.rollitup.org/t/diy-led-grow-lights-with-cree-cxa3070-cobs-and-cpu-coolers.805681/

[AscPete]

Thanks for the link...

I think that they have the money to invest, its a business.
There are COB LED floodlights at the same low prices, 12 - 50 watt Floodlights should cover it.

[AscPete]

Daniel,

Welcome to our figs forum community.

Thanks for sharing your photos, info and link...

My original seed starting lights were 2' x 4' T12 light troffres which I'm currently upgrading to T8's with new ballasts, since I also have to purchase new bulbs. They had not been used for several years due to the availability of suitable south facing windows.

[Daniel-PacificNW]

Pete, thank you.
For me, lights really get a head start on the growing season. Starting some plants, including fig starts, in January or February, I think adds a half year or more. Makes a big difference. Does not need to be expensive. The most complicated part for me was thinking about what wavelength was best.

[AscPete]

I did some calculations for the cost of material required to upgrade my 4 lamp T12 light troffers (4 total) and inexpensive manufactured LED lamps that were recommended by members as grow lights, http://www.ourfigs.com/forum/figs-ho...3549#post53549 , http://www.ourfigs.com/forum/figs-ho...3946#post53946 . The LED flood lamps with 6500k (Cold White) or 3000K (Warm White) diodes seem to be the most cost effective. The minimum upgrade cost for one T12 fixture to a T8 with four T8 bulbs is $40.00.

The comparison to the most cost effective LED equivalent is;

T8 Retrofit...
... 87 lumens / watt & $0.0038 / lumen (10,400 lumens, 120 watts @ $40.00 , 2 - T8 Ballasts & 4 Florescent bulbs)

LED... http://www.ebay.com/itm/50W-LED-Floo...3D151015708053
... 104 lumens / watt & $0.0042 / lumen (10,400 lumens, 100 watts @ $44.00 , 2 - 55 Watt Soft White 6500K Flood Lamps)

Since the actual LED numbers are better (20 less watts consumed) and the costs are so close I've opted to purchase and test the LEDs as grow lamps and will update this topic as the light bar is fabricated and tested. The fixture will consist of a 36 inch long "bar" with the 50 watt LED lamps mounted 12 inches each from center line (18in CL) or 24 inches apart. If they don't work as re-purposed grow lamps, they will be used for their intended purpose... outdoor lighting.

[fitzski]

thanks, Pete. I'm very interested in how the build goes seeing I need to expand my setup to accommodate the growing fig forest.

http://www.ourfigs.com/forum/figs-home/52404-any-change-in-your-2016-propagation-indoor-set-up?p=52639#post52639

I'm debating between fluorescent and LEDs for the 2nd level.

[AscPete]

Kevin,
You're welcome.
I'll also post the photos of the light stand and any other completed fixtures next week when the LED Flood lights arrive.

I was planning on posting to that linked topic /thread after I got everything assembled.

From all the positive info about the 6500K LED's they are working effectively in Reef Aquariums and 'Grow Rooms'. The 3000K LED's are also effective in the flowering stage for the 'Grow Rooms' so they both should work for propagating mere fig cuttings.

The only problem that the LED's may pose in the optimal height (distance) above the plants, they may need to be higher than the normal Florescent heights, if you're cramped for space it may be a problem... I've ordered a few lower wattage LED's for testing just in case.

[AscPete]

Some surprising preliminary power usage measurements...
The comparisons are between different T8 florescent bulbs (GE 6500K and 3000K) / T8 LED bulbs (Philips 17 watt 4000K) / 2 different T8 fixtures and / 50 Watt LED Flood Lights. The measurements were taken with a KILL A Watt P4400 Power Usage monitor. It just paid for itself since I will be returning the new T8 fixture and saving myself 20 watts of electricity (a possible ballast issue).

New 2 bulb W*mart (Lights of America Shop Light) T8 fixture... 122 vac @ 59.7 Hz
6500K T8 Florescent - 72.1 Watts
3000K T8 Florescent - 76.0 Watts
4000K T8 LED - N/G would not light...

Old retrofitted T12 fixture (Lights of America Shop Light) with Sylvania T8 Ballast... 122 Vac @ 59.7 Hz
6500K T8 Florescent - 53.5 Watts
3000K T8 Florescent - 52.2 Watts
4000K T8 LED - 38.2 watts

New LED Outdoor Flood Lights... 120 VAC @ 58.6 Hz
6500K 50 Watt Lamp#1 - 29.1 Watts
6500K 50 Watt Lamp#2 - 28.6 Watts

Once the light brackets are complete the next measurements will be actual Lumens per square foot or Foot Candles (1 FC is equivalent to 10.76 Lux) at 1 and 2 feet above the 2ft by 4ft growing area.

[fitzski]

Pete,

It looks like your LED fixtures are about 2' above the top of the domes and are covering a roughly 2-3' x 4' area. Is that accurate?

Have you determined the optimal distance between the bottom of the LED fixtures and the plants yet?

The top of my propagation bench will be where the larger plants will be residing which is roughly a 3' x 4' area.

I'm just not sure if I have the height necessary for the LED lights.

thanks

[AscPete]

The Flood Lamps are ~ 20 inches above the pegboard...
The pegboard / growing area is exactly 24 inches by 48 inches (8 sq ft), They could possibly cover a larger area (3ft by 4ft)

The lights can probably be as close as 6 inches above the canopy, but haven't tested that as yet. The next tests will determine best canopy distance, the amount of light (Lumens) and temperatures at various distance from the lamps.

[fitzski]

ok, so the LEDs are probably 10 inches above the domes right now.

I just did a quick measurement of my area and i have 29 inches from the bench to the bottom of the hanging propagation shelf.

So if the total depth of the LED fixtures is less than 9 inches then i would be able to have fig tree that is up to 14 inches tall.

I'm not sure that is going to be enough clearance.

With a fluorescent fixture I only need about half the depth and the plants can pretty much touch the bulbs.

Maybe I'll switch to LEDs for the upper bench. They'll just be as high as they can go between joist cavity.

What do you think?

[AscPete]

Yes, ~11 inches above the 7 inch domes.

The fixtures are ~ 5-1/2 inches deep including the mounting brackets, 4 inches deep without the bracket.
The face of the lamp (Glass) stays relatively cool, but the back heats up, but in this case only 30 watts of heat maximum .

One of the many questions is whether the intense light in close proximity will harm the young leaves.
BTW in my case I can extend the side legs of the light stand another 18 inches from their current 24 inches (to 42 inches max.). I will also be testing the 50 Watt LED Slim Lamps.

[DBJohnson]

Pete, would you mind posting a link to the LED lights you're using?

[AscPete]

in post #18, http://www.ebay.com/itm/50W-LED-Floo...3D151015708053

[AscPete]

The 4 ft T8 LEDs are from H*Depot and are linked and compared in this post, http://www.ourfigs.com/forum/figs-ho...3549#post53549

[pppldj]

If someone buys 4 ft LED T8 bulbs, be aware that all are not created equal. Be sure to read the package. Some require that the ballast to be wired OUT of the circuit. Others require that the ballast be in place. In Philips vs. Cree with like claimed lumen output and kelvin burning side by side, The Cree is noticeably brighter. I have not seen spectral analysis to know which gives more in the blue and red wavelengths but I suspect the Cree is superior. The Cree is about $23 and the Philips is about $10.

[AscPete]

Thanks.
Yes there are Two (2) different types of LED tube bulbs, one that has its own internal LED Driver / Ballast and the other that works with the existing Florescent Ballast. The above tests are being performed with the latter type bulbs, Philips T8 @ $10.00 each.

This link has some info with wavelengths listed in chart and text form for some of the popular Kelvin LED #'s, http://www.bmlhorticulture.com/indiv...-white-series/

[Harborseal]

A few things, probably in reverse order

It's true LED bars will not be the same and you should get the output spectrum and specs before you buy. The human eye is most sensitive to green wavelengths so a bluish light will seem brighter than a reddish light even if the reddish light has 30% more lumens. Greenish light is less efficient at stimulating photosynthesis so your eye is a poor judge of which lamp is best for plants.

Lumens is a measure of the total light put out by a bulb or other luminous object. It is not what the plants receive. 4000 lumens spread out over a 4' tube will give a single point less light than 4000 lumens spread out over a few inches if the distance from the center of the source to the point is the same. If 4000 lumens is delivered from the same source the bulb that's closer to the plant will give it more light. What you want to measure is foot-candles or lux (English vs metric). That's the measure of illuminance the plant receives at a particular point on a leaf.

29" is plenty of space to grow plants under LED or fluorescent lamps because by the time they reach 14" they're too big for low lumens, overhead only lighting. By low lumens in this case I mean under 25,000. The leaves shade each other out and the plants have to be spread further apart. You have to have 2-4 lights per plant because they don't fit in the area well lit enough to make them grow properly.

Remember that plants need 2000 foot-candles or 21528 lux on all of their leaves for optimum growth. At 14" tall overhead-only lighting under 20,000 Lm is only going to give the uppermost leaves enough light. If you direct light to the plant from 2 sources that improves things but eventually (and 14" is pretty close to eventually) that's not going to work with Fluorescent tubes and will be too expensive with 2 - 4 LED lamps shining on each plant.

So you have some options:

1. Delay starting your plants so they never exceed 10-12" before you can put them outside
2. Buy more lights - CFLs or more LEDs like these or the ones AscPete showed you.
http://www.ebay.com/itm/271890664022...%3AMEBIDX%3AIT - it always says last 1

http://www.ebay.com/itm/221968745639?_trksid=p2057872.m2749.l2649&var=520850160583&ssPageName=STRK%3AMEBIDX%3AIT

or these

http://www.ebay.com/itm/US-7W-12W-15W-18W-22W-28W-LED-Corn-Light-E12-E26-E14-E27-B22-5730-SMD-Bulb-Lamp-/191688854127?var=&hash=item2ca18bca6f:m:mHoTGVDKDahyBXeAsTnO3jg

5. Switch to an HID lamp with over 110,000 Lm as in

http://www.amazon.com/Apollo-Horticulture-GLK1000CT24E-Digital-Dimmable/dp/B0054LXQHY/ref=sr_1_1?ie=UTF8&qid=1450545576&sr=8-1&keywords=apollo+hid+tube+1000+watt

3. More I haven't thought of.

[AscPete]

Thanks for sharing the info. I was hoping that you would chime in
The LED screw in E27 bulbs look interesting...

I am aiming for 2000 FC at 1 ft (12 inches) from the LED Flood lamps @ their rated 6000K - 6500K, since Florescent Bulbs @ 6500K and ~1050 FC can provide sufficient light for seedling and stem cutting propagation.

[Harborseal]

Ummm. I'm not sure you are saying whaty you mean so let me translate your comment as I understand it and see if it's what you really mean.


I am aiming for 2000 FC at 1 ft (12 inches) from the LED Flood lamps <--So far so good


@ their rated 6000K - 6500K <-- which is a measure of the color of the light or CCT but not the output spectrum. That will be very different in an LED

, since Florescent Bulbs @ 6500K <-- again a CCT

and ~1050 FC <------- that looks good but the FC or Lux will vary not only with distance *from* a fluorescent tube, but also at the center vs away from the center towards the edges.

can provide sufficient light for seedling and stem cutting propagation.

I don't think I can post pictures here so I'm going to show the LED Spectrum in a new post.

[Rob Ster 010]

I'm using Mammoth T5 Neon 2 x 75watt and had great results last year. Daylight bulbs 6500K.

[AscPete]

Thanks for sharing the photos and info...

10,080 Lumens, 116 Watts, 22 cm x 60 cm (~ 8-5/8 x 23-5/8 2 lamp fixture) it produces more Lumens than a 4 bulb 2ft long T5 High Output lamp, http://www.htgsupply.com/Product-HTG...High-Output-T5 (@ 8,000 Lumens, 96 Watts)

[Harborseal]

Rob, show them a photo of the bulb. As far as I know your bulb is still not available in the US. Does it run on 220V or 120V? Thanks.

[Rob Ster 010]

Harborseal this is the 2 x 55watt version but the bulbs are shaped the same.
They run on 220 volt but i guess you can use them with a power converter.

[Harborseal]

Thanks! It's a very unusual and powerful tube. It may not be possible to make something like that run on 120V without some kind of step up transformer.