Author Topic: Grow Light System  (Read 20756 times)

Offline Aelah

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Re: Grow Light System
« Reply #30 on: April 14, 2010, 10:09:58 PM »
We've been experimenting with seed starts a bit, and here is what works for us.

Our guest room has been taken over at various times of the year for seed starts. We've got an extensive 3-tier growlight system once germination has occurred. We have the lights set to a timer and will vary the exposure time depending on what plants are under them. Veggies 12-15 hours, houseplants 6-8 hours. The lights should be just barely above the tops of the plants (1-2").

As for pre-germination, the most effective method we have found is to use a good potting soil, dampened. Plant seeds to the specified depths, then water three times, waiting a bit in between... soil takes alot of water. Afterwards, we cover the trays lightly with saran wrap (forget the plastic covers) and place on a heat mat. Most seeds germinate with good moisture and heat, not CO2/O2. Ideally, it's great if you can use a heat mat with a thermostat to adjust to optimal temperatures for each variety, but you can cut expenses and have good results with just a basic heat mat. Start peaking under the saran wrap after a few days.

Once the first signs of germination appear, remove the saran wrap completely, and water if needed. At that point we move new seedlings to our growlights while keeping them on heat mats where they remain until they are transplanted up to larger containers, at which point we begin a gradual hardening off by moving them to the greenhouse until planting day.

We've used both the large heat mats (holds 4 trays) and the single size. I like the large size for mass germination, but it doesn't fit easily in my growlight trays so we acquired enough heat mats over time for us to have the small size permanently under the grow lights and the large ones for initial germination. It's effective because it allows us to "cycle" plants that are family favorites, like lettuce, so we can have a constant supply.

Edited to note: When we have starts going, we leave the heat mats on continually until we pot up, unlike the growlights which are on the timer.
« Last Edit: April 14, 2010, 10:13:22 PM by Aelah »

Offline Stein

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Re: Grow Light System
« Reply #31 on: April 16, 2010, 06:55:34 PM »
I just did a bit of research, thinking about how to improve my system.

The web says sunlight is about 130 Watts/square foot.  Obviously this varies dramatically across the world and during the seasons but is a good place to start.

I have four 40 W tubes lighting an area roughly 4' x 1' = 4 square feet.  Out of the 160 W, probably 30% is not effectively reflected down, so I have about 112 W available for the plants - assuming they are touching the light.  Since they aren't, let's say 100 W hits the plants.

Sunlight would be 620 W, just over six times the amount of energy I am currently providing.

I think next year I might add another fixture so I have three next to each other.  The middle one would be mounted normally and the outside two would be tilted to shine inward.  That would give me another 40 W, but still nothing compared to the real thing.

Or, I could build a small greenhouse with an electric heater.

matthewpaul

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Re: Grow Light System
« Reply #32 on: April 16, 2010, 09:11:35 PM »
I've been keeping the heating mat and lights on the same timer and shut off for 6-8 hours per day.

Offline trucker larry

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Re: Grow Light System
« Reply #33 on: April 29, 2010, 04:02:32 PM »
Great post, Stein, showing just much more effective the sun is than artificial lighting.
Question: your calculations are for flourescent lights, i think. Did you do any figuring on the LED grow lights? I bought a 1ft square led grow light a month ago (from Amazon), and I gotta say I am pretty impressed with it. I went w/ this as a test evaluation. After seeing the results, I think I will plop down some $ for some more. But i would be interested in what your figuring has told you about the LEDs...

Offline Stein

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Re: Grow Light System
« Reply #34 on: April 29, 2010, 10:19:40 PM »
Great post, Stein, showing just much more effective the sun is than artificial lighting.
Question: your calculations are for flourescent lights, i think. Did you do any figuring on the LED grow lights? I bought a 1ft square led grow light a month ago (from Amazon), and I gotta say I am pretty impressed with it. I went w/ this as a test evaluation. After seeing the results, I think I will plop down some $ for some more. But i would be interested in what your figuring has told you about the LEDs...

I haven't seen the LEDs in person yet, but they should be rated in Watts just the same.