Hello Mayo,

Bulb types are explained here:
http://en.m.wikipedia.org/wiki...

And here:
http://www.gelighting.com/Ligh...

I've grown a variety of plants, including daylily seedlings, under lights, and I've always used one daylight tube and one "Grow" tube in each fixture, but for strictly sprouting and growing daylily seedlings to transplant size, I'm not sure how important the flowering wavelengths are, or if a growth-only setup might actually be better.

If you were growing flowering plants, such as cactus, succulents or African Violets you would need to pay more attention to that end of the spectrum.

Lumens are a unit of light measurement that specifically relates to the parts of the spectrum which can be perceived by the human eye. I think its origin is in consumer protection, but also has the secondary effect of encouraging efficiency in light design. Lumens may not be the best way to measure light output for horticulture, since plants also react to light in the non-visible parts of the spectrum, but it's the most commonly used rating system.

The configuration of your growing area will play a part in which way you go regarding lamps. How many seedlings are you going to grow, and how big is the growing area? Is it going to be inside the home or in a cold garage? If the latter, do you think you'll need some bottom-heat?

The HID 400W lamp throws a lot of light (and heat), and offers the simplest set up, but in order to evenly illuminate a larger area it will need to be held up a few feet from the plants. Light intensity follows the inverse-square law, meaning that the intensity decreases as the square of the distance from the source, so a lot of that light will attenuate by the time gets to the leaf surface. Also, it's a 400 watt all-or-nothing proposition. If you run several growing stations of 22" X 22", you can shut off any unneeded lamps.

The high-power 75W fluorescents you're looking at are probably a little too strong to double-up in fixtures. Compared to conventional (T8) fluorescent tubes of similar length, they provide about 3x the light.

My basic grow station uses two 24" T8 tubes at 20w each per fixture, with 2 of these fixtures spaced to cover a 22 inch X 22 inch growing area. This holds 24 3.5" pots, with up to 10 seedlings in a pot, and uses 80 watts of power. I have two of these in my garage. Growth is good, but I run the lights right down on the foliage tips. I think fluorescent light is most effective and efficient this way. If you put 2 of those 75W lights in a fixture, it might be a bit more concentrated than necessary, and when using fewer but more powerful lights, you might start to see areas which are not as well-lit as others, and might even see leaf damage. I think 2 single-lamp fixtures using the 75W "Cutting" lamps would light the same area extremely well. (150 W vs. 80W) I also have white board surrounding the growing area to bounce light back into the plants. A sheet of cardboard or plywood painted flat white is highly efficient.

Keep in mind that if you "under light", you can go closer or add more lamps, but if you "over light", you have to raise the lights and still pay for the extra electricity.

It's an interesting "problem", and if I was starting over, I might be tempted to try some of the newer technology.

Good luck, and be sure to have a plan in place to effectively deal with fungus gnats before you get started.

Ken

I concur about the fungus gnats! They can kill your seedlings!

I found this article about using H2O2 to kill fungus gnat larvae:
http://forum.grasscity.com/sic...

Interesting, because I do use H2O2 mixed in the Spring water I use to water my seedlings when I start them inside on the window shelf. Sometimes I have a gnat problem and sometimes I don't. Must be the amount of H2O2 that I add to the water before watering everything.

hi Ken,

thank you véry much for your information!

I have 50 pots ( 6"x 6", 9" high) with seedlings that I sprouted at the end of this summer.
I was planning to keep them on my porch during the winter, but we had 3 big storms in November and my seedlings suffered quite some leaf-damage
So.. I am looking into keeping them in the (unheated) garage instead
The size of the area I will use in the garage can be as big or as small as I want (my truck is not in it )

I had never heard about special lights for plants before but, as it is legal to grow your own marihuana here , it turns out that there are special 'grow shops' here where you can buy everything you might need to get the best results..
So I can choose from all kinds of lighting systems, heatings mats and even special 'tents' to reflect light and warmth (for instance : http://www.onestopgrowshop.co.... )
I can buy such a tent, or use reflecting sheets, whatever would be best.

If I don't go for the heating mats, a stove or something, temps in the garage míght get around feezing at night somewhere during the winter. Is that a problem?
I'm not trying to germinate seeds, just give my seedlings what they need to grow and be healthy.

I can order nematodes if I get gnats, that is not a problem


Mayo

I'd heard of grow tents for indoor plants, but never seen one until I looked at that website link you listed. Quite a set-up! I don't think you would need anything quite like that. Being so cold in your garage, they might go dormant or drop foliage in those temps.

Hi Mayo,

It's the same situation here with the "Indoor Gardening" shops. They cater mostly to the marijuana growers, with a focus on hydroponics, but they're also the only place to get the more esoteric gardening supplies. The problem with that whole business is that most of their customers have little to no gardening experience, and fall prey to the abundant gardening myth attached to pot growing. There's a point of diminishing returns when it comes to any horticulture, so while some of the more exotic growing techniques and advice do have some beneficial effect on the plants, it may come at a very high cost. The first $100 you spend on fertilizer and soil mixes will produce very noticeable and worthwhile returns, but if you spent $200 on "boutique" products, the result might be 5% better. Maybe.

With 50 6" containers, you'll need an area about 3.5 to 4 foot square, which would probably be most conveniently lit with the 400 W bulb and a proper reflector, plus side-reflection boards. I'm a little warmer here than you, and I think the coldest I ever found the garage was just under 40° F with outside temps of around 30° - assuming bright days in between to re-warm the garage and its contents.

I think a tent might hold more heat than you need after that light burns for a few hours, but some low-wattage heating mats under the pots would keep the soil temps at a good growing temperature. (I'm guessing here, but 55°F might be good enough—it'd be best to research this one.) Use a good thermostat with a probe you can stick in one of the pots, and you might also want to put it on a timer to come on about an hour or two before the lights. I'm not aware of any heat mats in that size, but surely someone makes a 2' x 4' model. If you're worried about reaching freezing temps inside the garage, you can run the heat mats around the clock controlled by the thermostat. If you provide long enough day length for the plants, I doubt many will try to go dormant. Any that do would probably be better off outside.

Put down some styrofoam insulation, then the heat mats, then a sheet of heavy plastic with the edges lifted up over a simple square frame of 3-4" boards to hold any watering runoff. You'll probably have to work to control spider mites since it will be a dry atmosphere. A fine spray of water directed upward at the underside of the leaves once a week will go a long way toward keeping the mites down.

If you don't go with a heat mat, then you might have to use a tent, just keep an eye on the internal temps. A small oscillating fan is always good to blow the leaves around to promote more sturdy growth and keep the temperatures even (run fans on the light timer). A serviceable tent is fairly easy to make with some plastic sheets hung from wood rails anchored to the ceiling. I don't think you'll need full enclosure, but if conditions force you to put a lid on it, make it high above the light so there's no chance of it catching fire.

It's only critical with the big 1000W lights, but nevertheless, make sure your electrical system is up to the task. You might want to run your heat mats on a different circuit than the light. Make sure the wiring in any extension cord you use for the lamp is rated for a continuous load of 500W. 14 gauge is good.

Sounds like a fun project. Take lots of pictures, particularly "before and after" pictures of the plants.

Ken

CaliFlowers said:

Put down some styrofoam insulation, then the heat mats, then a sheet of heavy plastic with the edges lifted up over a simple square frame of 3-4" boards to hold any watering runoff.

The heating mats I have and have seen are all waterproof. What you suggest with the frame of boards would result in tremendous pooling? I just use very thin plastic trays. Heat mat is directly on pieces of styrofoam insulation.

Most info I have seen and what I use is to remove the heat mats when the plant has two sets of true leaves or ~ 3" tall. Heat mats put out very little residual heat. If more heat is needed to keep above freezing, some other source is needed. Basically I just use them as heat for germination and early growth.

Among other lights, I run two of the warehouse type lights whose shroud is ~ 20" across. The bulbs are 400 watt metal halide. They are about 7 feet above the floor (I can raise them to ~ 8 ' and lower them as much as I need) and light up an area about 12 ' x 10' plus. What I consider the residual light from this is about 2 feet wider and long. Near the bulbs, they put out a lot of heat so I cannot get them too close. When I run these they raise the temperature in the area ~ 4 deg F.

I've been looking and looking on line for a T5 set up for lighting. Wanted to purchase locally (Fleet Farm or Menards). Menards has a T5 HO fixture with tubes included for 80.00 but I really don't want to pay that much at this point (just a beginner). Also I prefer not to have the heat that it sounds like you get with the HO. This "operation" will be in an enclosed porch that is heated (two outside walls but still should keep plenty warm I would think). North windows will have light coming in but NO direct sunlight.

Do you think the fixture (described below) will fit the bill for my needs. The on-line price is 19.99 (T8 lights NOT included). Since I will need two or three fixtures (depends on how many seeds germinate) this is much more in line with my pocket book. I'm thinking this should be okay but I'd like everyone's advise...will I regret going with the T8's? in advance.

The American Fluorescent 2-light T8 51.625" titanium performance plus shop light has a 120 volt electronic ballast, quiet operation and a 0º start-up. An 8' power cord and hanging chain set is included. It produces 120% more light than standard T12 models with an optimized wide reflector. It features an On/Off pull switch and can be used over a workbench, in garages or anywhere general lighting is required.

Model Number: PPS232RC | Menards® SKU: 3481420
•Length x width x height (in inches): 51.625" L x 8.5" W x 2.875" H
•Number of lamps: two T8 or two T12 lamps (not included)
•Plug-in
•Voltage type: 120 volt residential
•Starting temperature: 0 degree Fahrenheit
•Mounting accessories: "S" hooks and chains included
Shipping Weight: 6.7 lbs

How much is shipping? So it produces 2.2 x that of a standard T12? Percentages can be so misleading or confusing.
This is ordering on line from Menards? Using standard seed starting 72 cell trays? You can get 2 - 4 under one light.

Handling 2.80 plus shipping 6.74 = total of 9.54 if I order three fixtures (from Menards). Don't know if I'll need the third but I'd probably get it just in case. The retail of each is 29.98 but the "on-line" price is 19.98 each. I'm going to check at the store to see if by chance they are the same price in the store.

Yes, I'm using the 72 cell trays. I don't know how many seeds will germinate or how many seedlings I want to attempt. Four trays would get me 288 cells. I have over 1000 seeds even after giving some away. So, I just may use a six trays.

Below is a comparison T5 vs. T8 that I just found on the internet. Not that I even understand all of what they say but it seems that most of what I read on the internet often relates to how they "light up a room" vs. what we are using it for.

Advantages and Disadvantages of Both the T5 and T8

T5: Advantages
##Better Light Control.
##Smaller Cross Section and Size.
##Smaller Ballasts.
##Various Lengths.
##Good Color Rendition Availability.
##Good Color Temperature Availability.
##Better LPW (lumens per watt) Efficacy.
##Better Photometric Performance.

T5: Disadvantages :
##Differing Lumen Outputs Among Manufacturers.
##Changes in Light Output Between Enclosed Luminaries and Bare Lamps.
##Changes in Light Output Between Indirect and Direct Luminaries.
##Vertical versus Horizontal Burning Variables.
##Lumen Variations between 25 degrees and 35 degrees Resulting in a gain or loss of 10% light output.
##Reduction of Lamp Life when PS is Not Used (IS is good for long-term use).
##Position and Temperature Sensitive.

T8: Advantages
##Industry Work-Horse.
##Come in Various Color Temperatures, Color Renditions, and Lengths.
##Less Fragile When Compared to a t5.
##Easy to Use For Replacing t12s.
##Energy Efficient.
##Good Lumens at ‘End of life’.
##Uses PS When Sensors are Deployed.
##Costs Less Than the t5s Now.

T8: Disadvantages
##The IS and Sensors Reduce the Lamp Life.
##The Lamp Contacts Cannot be in Contact with Grounding Areas.
##Lamps Fail When Replaced Without Shutting Power Off.
##Lamps are Incompatible With Ballasts.
##Lamps Fail When Not Being Used in the Ambient Temperatures They Were Designed For.
##The Ballast Factor
Final Thoughts: It comes down to the fact that a t5 creates more usable light than the t8. Even though that’s true, it is not so superior that it renders the t8 as being obsolete like the t12.

petruske said:Handling 2.80 plus shipping 6.74 = total of 9.54 if I order three fixtures (from Menards). Don't know if I'll need the third but I'd probably get it just in case. The retail of each is 29.98 but the "on-line" price is 19.98 each. I'm going to check at the store to see if by chance they are the same price in the store.

Yes, I'm using the 72 cell trays. I don't know how many seeds will germinate or how many seedlings I want to attempt. Four trays would get me 288 cells. I have over 1000 seeds even after giving some away. So, I just may use a six trays.

Sue - there are 2 or 3 threads on ATP now that are discussing Fluor lights. There is a LOT of info being posted, comparing, etc.

So if you order on line the total is $ 29.49 and you have to buy 3. In store it is $ 29.98. So you save 50 cents. Heh. But I presume some of the stores probably don't have these. And you still have to buy bulbs.

BTW - you likely want to check out heat mats.

beckygardener said:I was told years ago to use 1 "warm" light and 1 "cool" light in each shop light fixture to emit the full spectrum of light needed for the seedlings to grow well. That is exactly what I did.

That is what I did as well. I just did not want to spend the extra $$$ for "grow" light bulbs. Subsequently bulb technology came out with the "natural" light or full spectrum. When you use them, they provide essentially the same resulting light as using one warm and one cool. That is what typically I use now

Well have had some mixed results so far. Some seed crosses didn't really germinate at all, or if they did, the put out the white root tip sprout and then stopped. Other crosses are doing great. I have more seeds soaking now as well. Also today I met up with David Hansen and he was nice enough to give me and a friend some nice crosses, I'll probably wait to start those based on his recommendation. The seeds I already have going might get too big before I can get them outside.

As for light they are by a south facing window and I have an LED shoplight (4 foot two tubes) over them for extending the photoperiod to 14-16 hours a day.

Do any of you have a tried and true "brand name" for heat mats.

I use HydroFarm - one purchased at Lowes and one purchased on Ebay. They sell at least two sizes. Mine is the smaller size that fits under a standard seed starting tray.

I also have their adjustable thermostat, but I question its value.

I have this shop light which I got from Home Depot several years ago when they were less than $10 a light. They are now $16+. Then I had to buy light bulbs which I bought in bulk for fairly cheap, too.

http://www.homedepot.com/p/Lit...

Well Becky at least you can rest assured according to the government data, there is NO inflation. [Sarcasm]
There is NO rational reason why that thing went up at all. None.
I am an Engineer and an Economist.

Here's a good reference page to get you started, showing a wide variety of sizes. Most of these are the "low-wattage" type of mat, which don't really require a thermostat. There's even a handy windowsill mat.
http://www.charleysgreenhouse....

I have one of the 20" x 20" HydroFarm mats and it's still going strong inside the garage after about 4 years. The thermostat seems to work OK, but it's plastic, with a plastic soil probe, so doesn't appear to be built with longevity in mind.

Charley's also offers a couple of heavy-duty, high-wattage mats that require a thermostat. At least 25 years ago, when Charley's was a fledgling start-up, I bought two of these thermostats and one each of the 22" x 22" and 22" x 60" red rubber mats. They're all still working today. These are sturdily-built, professional-grade products, appear to be made in the USA, and are designed to hold up in a commercial setting. They're essentially two sheets of belted rubber sandwiched over a heating element, reminiscent of a conveyor belt or a truck mud-flap. The thermostat is accurate and responsive.

H-D Thermostat
8035 Heat Mat Thermostat 1 Outlet (E34351)
http://www.charleysgreenhouse....

22 x 22 mat (100 watts)
http://www.charleysgreenhouse....

22 x 60 mat (180 watts)
http://www.charleysgreenhouse....

Ken

Wow - pricey

Some HydroFarms on Ebay. Windowsill unit for 19 $.

http://www.ebay.com/sch/i.html...

I just ordered four of the Hydrofarm MT10006 mats 9" x 19.5". at www.midlandhardware.com

They were only 17.82 each. (They retail for 29.99.) Shipping for all four was only 6.95. That is the best price I could find on the internet.