Grow Light questions

[tlcmd]

Soon I will be starting some of my seeds for spring in seed flats; hoping to start tomatoes, peppers, wormwood, and basil.

My questions re: grow lights:

1) Do they need to be turned on as soon as the seeds are planted in the growing medium or after they germinate?

2) Do I need to use a timer to allow 6 - 8 hours of darkness/day? I have heard that this is necessary after the plants are 3 or 4" high and not before.

Comments and opinions, please.

Thanks,
tlcmd

I started my pepper seeds on Nov. 20. I will start my tomato seeds in mid December on the same light table. I started my timer for twelve hours of light and twelve hours of dark when I started the pepper seeds. The cycle will continue until I move all the plants outside into a cold frame in mid February.

I don't know if it is "necessary" to do it my way, but it has always worked well for me in the past. My four T8 florescent bulbs operating twelve hours per day, only cost about $5.45 per month to operate at $0.095 per kwh.

Ted

[Tom A To]

You don't need lights until after the seeds germinate although that's not true for all seeds, i.e. those that don't get planted under the soil but instead on top of it, like impatiens.

I start the lights as soon as the seedling breaks the soil surface. I think waiting until they are three to four inches high would make them too spindly. I keep the lights on for around 17 hours/day. I also start to wiggle them right away, by shaking their container, blowing on them, passing my hand over them and sometimes a quick pass with a hair dryer without the heat turned on.

If the weather permits, right away I start taking them outside during the day for some exposure to real sunlight. Starting with 30 minutes exposure and working my way up to all day. The process of moving them everyday takes care of the "wiggling" bit. Using this method, I produce plants that have thick and sturdy stems by the time I give them away, plant them or donate to the garden club for selling.

Million ways to do it, that's just how I roll.

[Worth1]

I run my lights for 15.59.099.
No more no less.

Worth

[tlcmd]

To all y'all,
Thanks for the info. I have usually used an 18 on/6 off, but thoughi'd see what others are doing.
tlcmd (aka Dick)

[nnjjohn]

I bought the low 2 or 4 watt LED grow bulbs which are suppose to be extremely energy efficient compared to regular ..even florescent tube fixture. Anybody try them yet? Yes , I learned here awhile ago to hit them with indoor light as soon as they germinate. And after they are a few inches ..gradually expose them to outdoor sunlight. I remember the days when I fried my seedlings leaving them out too long in the warm sun rays.. ended up having to buy my tomato plants from a local nursery.

Originally Posted by nnjjohn

I bought the low 2 or 4 watt LED grow bulbs which are suppose to be extremely energy efficient compared to regular ..even florescent tube fixture. Anybody try them yet? Yes , I learned here awhile ago to hit them with indoor light as soon as they germinate. And after they are a few inches ..gradually expose them to outdoor sunlight. I remember the days when I fried my seedlings leaving them out too long in the warm sun rays.. ended up having to buy my tomato plants from a local nursery.

I've always wondered about the effectiveness of the light output of low wattage lights. Can light produced with 3 or 4 watts of energy stimulate photosynthesis in plants to the same degree as light output from a forty watt source. I know light can be perceived by my eyes as the same intensity from both sources, but plants may not perceive it the same. I have a large spotlight powered by a high voltage lithium Ion battery. I also have a head band light with a single light emitting diode powered by three AAA batteries. Both lights produce almost equal high intensity light beams at night. I suppose it is simply a matter of the efficiency of different light sources converting electrical energy to light energy. We used to have some lighting experts on this forum. I hope one of them can explain how much light is needed by germinating plants.

My reason for turning the lights on when I plant the seed is the possibility of the light producing heat when it contacts the dark colored growing medium. I only keep the room temp. at 70 degrees F. and the pepper seed needs a little more heat. The pepper seeds started germinating at ten days. The light may not help, but I don't think it hurts.

Ted

[Worth1]

This is a big mix up that I wish they would quit.
The watts on the LED light is the amount of electricity it consumes.
It has nothing to do with light output.
People are used to the incandescent bulbs saying so many watts and are stuck on it for light output.
The LED light will then say it is equal to a 60 watt light bulb or what ever.
Some will say candelas or lumen.
Also beware of grow lights.
They are all over priced and dont do much if any better than a standard bright daylight tube.
And furthermore, many aren't fit for anything but house plants that like the shade.

Every bulb I change out in the house is now an LED.
Reasons,
They dont consume as much energy.
I can get more light in an area without worrying about burning out my fixtures.

I wish I could experiment with the LED lamps for growing but right now I cant.

Worth

I know your correct Worth. Incandescent, Fluorescent, and LED can each be rated the same as a 60 watt incandescent. It simply means some technology is more efficient at converting electrical energy into light energy measured in lumens. I always assume the statement means visible light detected by the naked eye. I don't think it means the full spectrum of light the eye can't detect, but is required by plants for photosynthesis. The LED will consume less energy (watts) to produce equivalent lumens than a fluorescent with very little heat loss. A fluorescent fixture will produce the lumen equivalent of an incandescent fixture with lower energy consumption and lower heat loss than the incandescent or halogen fixture. I don't know which light source best produces light in the full spectrum needed by plants.

I suppose I should locate a prism somewhere and use it on all three types of light fixtures to see which portions of the spectrum are not being produced.

Ted

[aclum]

Hi,

Straying a bit from the OPs original questions, but adding my 2 cents to the LED comments.....

If you don't already have your fluorescent fixtures, the (or some) LED grow lights might be more economical than the fluorescent. Just checking out a few websites, seems like a basic 4' fluorescent fixture plus 2 daylight bulbs will cost around $25.

I just ordered a couple of 168 red/blue LED lights from Tmart for $18 each:

http://www.tmart.com/E27-8W-PAR38-Re...FUQ6Qgodl2wAQw

It's very similar to the following light (and others in that approximate price range), but the following listing offers more specs at the bottom of the page that might be of interest:

http://www.espow.com/wholesale-par38...ixed-110v.html

You just need a regular light bulb socket attached to a power cord and coverage (according to the link directly above and others) is between 1.5 and 2 square meters (16 to 21.5 square feet). You'd probably need 2 or more fixtures to cover this area using fluorescent. Haven't checked prices, but a lamp socket and cord couldn't cost more than a couple of dollars.

LED is cooler running (my main reason for getting them), longer lasting, and more energy efficient than fluorescent (as Worth mentioned). And, if you're starting from scratch, it would be cheaper than the fluorescent.

So, ASSUMING the LED works as well as the fluorescent (an isn't a piece of junk ), and you don't already have your fluorescent lighting fixtures, the LED might be a better alternative (unless you prefer the fluorescent for aestheric reasons or the added heat generated).

I'm just now starting to learn a bit about LED grow lights, so take what a say with a grain of salt. It's JMHO, FWIW !

Anne

[AKmark]

I use High Pressure Sodium lights for starts and also have them on to germinate too, because they omit heat. They also have a reddish light spectrum that peppers and tomatoes love and fluorish under. On top of that, I believe they may be one of the more efficient concerning lumen output and cost. A timer is fine, saves a few bucks. If you want to set out big healthy plants, or many nice plants look at them.

[ohiofem]

For many years, I grew my starts under 4 4-foot shop lights, each with a 40 watt T12 warm light and a 40-watt 12-T cool light, so I had 320 watts over 16 square feet or 20 watts per square foot. I kept the lights about 1-2 inches above the plant tops. In spite of all the advice to the contrary, I ran my lights 24-7. This definitely increases the growth rate and I never saw evidence that it hurt my plants. Tomatoes typically grew to about 12 inches tall in six to eight weeks under this regimen. It cost me less than $15 per fixture to set up. The only problem is that light intensity falls off rapidly, and lower leaves don't get enough light once the plants are 12 inches tall, so you need to get them outside before they grow taller than that.

Three years back, I purchased a fixture with 8 4-foot T5 high output lights. It covers the same 16 square feet. I found that my plants did better with a cycle of 16 hours on and 8 off. I also need to keep the lights further away from the tops, at maybe 3-6 inches. The plant growth is phenomenal, but the height is about the same at 12 inches tall in 6-8 weeks. The difference is that they are much stockier with thicker stems, shorter distances between internodes and a lot more leaves.

As for how soon to put the seedlings under lights, I vote for doing it from the start. Seeds benefit from the warmth, and you don't risk evaporative cooling, which can bring the seedling mix at the top down 10 degrees or more below room temperature. This is especially important for peppers and eggplants, which need higher temperatures to germinate.

I rebuilt my light table this year with 48" T8 fixtures. I bought them at walmart for $10.00 each. That seems to be their standard price for the fixtures. I use two GE "daylight" bulbs and two of another GE lamp which I can't remember the name of. The "daylight" bulbs produce light with more blue in the spectrum. The other bulbs produce light with a pinkish orange color which is supposed to make colors in the home appear more true. They have more red in the spectrum. Supposedly the combination of the two types produces the full color spectrum needed by growing plants. The daylight bulbs cost less than $2.00 each while the others cost about $6.00 each. The setup was pretty inexpensive with off the shelf materials. I should know before very long how well it works. My peppers have started generating.

Ted

[Worth1]

The 16 hour cycle seems to do the best for me.
By the way I like the black cat in the picture above.

Worth

[Lorri D]

Yes, the cat steals the spot light...hahahah

I use fluorescent lights, because I am pretty new to starting seeds. They were less expensive, common and you don't have to get into all the ballast stuff etc...

Everyone is going to vary depending on their set-up and room. i.e. How warm is your room, are your plants near a window, use of fans etc... '

I have two, four ft, 4 bulb, T 5's, with 6500k daylight bulbs. I use 6500k daylight bulbs, because, they are the highest (K) I could find and they are for vegetative growth. I don't plan on growing anything through the flowering and fruiting stage, so I don't worry so much about the red spectrum. Last year I started all of my vegetable and flowers with them.

I have lights on them as soon as I sow them. Because, they give off the perfect amount of heat for germination and I want the seedlings to receive light as soon as they poke their heads up to keep them from getting spindly. I also use a fan for half a day on them to make them stronger and stockier.

I turn the lights on when I wake up and shut them off at bed time. That means they are in the dark around 6-8 hrs and my plants last year looked better than the local nursery. It took me 3 years to get my system right for me, including: lights, fertilizer, wind, starting times and potting up. Lorri D