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Indoor Vegetable Garden Lighting

If you are growing your plants indoors, it won’t do to just let your house lights handle the chore. On a small scale, growing in your kitchen, you can put your plants in the window sill if your reference-colortempkitchen faces the south or near about. If you have an outdoor shed or breezeway type grow area, though, additional lighting will be needed.

There are 3 types of indoor vegetable garden lighting that have been used for decades, now, and LED is making it’s way up the charts as of late. The other kinds are H.I.D. (High Intensity Discharge) such as Metal Halide and High Pressure Sodium or more common for the non-commercial grower, is T5 Fluorescent.

When buying lighting for my garden, I shoot for 5500 on the Kelvin scale. Based on a computer model, someone came up with the idea to heat up a block of black metal, and record the temps of the metal as it heated up and changed colors.So as it starts out it’s warm giving it a numeric value anywhere from 1500K (Kelvin) to around 4000K. These colors represent the colors of a warm white fluorescent bulb or a High Pressure Sodium bulb.

From about 4500K to 6000K, the color is much whiter, actually at 5000K, pure white. This is considered full spectrum. This is the light produced by a clear Metal Halide lamp, a Halogen Lamp, or a Cool White Fluorescent bulb.

As the block of metal gets even hotter, the light appears to fade to blue. Before it gets too blue, like around 6500K to 7000K, it is considered daylight fluorescent about the same as a clear mercury vapor light.

Nowadays, you can buy LED lighting in the High Noon spectrum, too. LEDs are more expensive than fluorescents, but can use less wattage and last longer, there by making it the sensible choice for some home gardeners.

When it comes to indoor vegetable garden lighting, some things you should consider are:  most effective color, electric consumption, size of the area to be covered, and of course, cost.

 Most Effective Color

Generally, when I’m looking for lights for my indoor garden, I concentrate more on the Kelvin scale. Plants use the full spectrum provided by the sun in order to grow. This means they like a red light for the flowering stage of growth and blue light for the fruiting stage.

If I can get a light that is at 5500k, that is usually considered full spectrum, daylight color temperature. I can utilize this light for the entire life of the plant.

Some people prefer to change out bulbs or lights to red when a plant begins to flower. Then, when the vegetable plant starts to grow fruit, they will change the light to blue. I’ve recently heard of some growers of hydroponics using one white fluorescent bulb with one multicolor fluorescent bulb throughout the entire grow term and producing very hearty plants.

You can see on the scale at the top that a metal halide lamp, a cool white fluorescent bulb and a halogen lamp would fall into the 5500k area, but a cfl or cool white fluorescent bulb would be much more affordable. A metal halide lamp or a high pressure sodium would most likely be close to 400 watts. They also burn much hotter than any of the other choices and would have to be kept a safe distance from the plants to keep them from getting burned.

Electric Consumption

We pay about $.0748 or 7.5 cents per KWH (kilowatt hour). One kwh is equal to 1000 watts per hour at 7.5 cents. So .075 divided by 1000 equals .000075 per watt. So if you have a metal halide lamp or a high pressure sodium lamp that burn at 400 watts for 14 hours a day, it would cost you 42 cents per day to operate it. .000075 x 400w x 14 hr. = .42 or 42 cents.

However, I use LED bulbs and CFL bulbs which consume much less electricity. My CFLs (compact fluorescent light) run at 27 watts with 5500k, and 2700 lumens. That means using the formula above, it costs me around 28 cents per day to use.

The LED bulbs use 9.5 watts, 5500k, with 990 lumens and cost .9 cents per day to light up my indoor vegetable garden.

Size of Area To Be Covered

For reference, a lumen is the amount of light output from 1 candle on 1 square foot of area, 1 foot away from the candle. So, if your garden is 3 ft. x 6 ft. you have a square footage of 18. Theoretically, any light or lights you use should provide at least 18 lumens if that light is only 1 foot from your garden.

That isn’t really practical. Metal Halide lamps at 4oo watts usually have about 36,000 lumens and High Pressure Sodium lamps at 400 watts have about 54,000 lumens. For a small garden, that is overkill. A lot of modern growers use them nevertheless. If your plant is expected to grow very high, you will need a pretty high ceiling because you will need to keep the HID lights at least 18 inches above the top of the plant to resist burning it.

The LED bulbs I use have 990 lumens and the CFLs have 2700 lumens. In my opinion, that is more than enough to grow a garden with. That is not to say your plants can’t still get burned, but those lights burn much cooler than the HIDs. Any plant that grows to the height of the bulb and stays there for any length of time will dry out or burn.

Upfront Costs

You can get a setup at Amazon that includes a 400 watt cooling ballast with a fan  a 400w Metal Halide, metal halide lamp inside36,000 lumen bulb, a 400w High Pressure Sodium bulb with 54,000 lumens, a reflector and a timer for $120.00. Add that to the cost of 42 cents per day of operation and that is your cost. Most of the HID bulbs last anywhere from 5000 to 15000 hrs. At 14 hrs. a day, it may be as long as 3 or 3.5 yrs. before you have any problems.

A T5 fluorescent setup like the one below can be had at Amazon for about $95. This price also includes the bulbs. You can get a 5 pack of bulbs though, later down the road for around $20. These bulbs are expected to last around 20000 hours.

T5 setup

 

You can also go to Wal-mart and buy a standard reflector socket for regular bulbs and use a CFL at about $9 or a LED for around $22. LED bulbs are given a 50000 hour life expectancy.

They do make strips of LED lights in blue and red, but the only ones I could find were in 12v versions which means you would have to have a converter to change your 115v electrical at your house or a solar setup with battery backup.

I saw a woman called Katie Phibbs on youtube, with a company called the Lettuce People. She does a demonstrations having to do with the efficiency of different lighting. You can click on Katie and see one of the videos.

An important note to remember is that HID lights emit quite a bit of heat. If you have an enclosed growing area, this can affect the growth of the plants. It will cost even more money to move the heat out of the room, through air conditioning, or fans.

However, if you are trying to grow summer vegetables in the winter, this might just kill two birds with one stone, so to speak (sorry PETA). It creates the heat that melons and other summer veggies like plus gives them more than ample light to bask in.

In any case, lighting can be very important to the health of your indoor vegetable garden. Be sure to comment if you have any opinion at all, for or against. Thanks for reading. Your ideas are important to me.

 



 

 

 

Broderick Snow

10 Comments

  1. Hi! I actually never could imagine using indoor lighting for growing plants at home. My energy costs are high. And all the electrical lingo made me reminisce on my late father, who worked as an electrician. But nonetheless, it’s a good alternative from buying from the store. By the way, my kilowatt-hour rate is about 26¢, so you can imagine how much it is a month. Great article!

    • Hey Nelly,
      Thanks for the comment. 26 cents per kwh is high, but even so, using a 9 watt LED for 14 hrs. is only 33 cents per day. My lettuce has been lasting for 3 wks. If you plant seeds every 3 wks., you should never run out. There is no seasons inside. At the grocery store I have to pay $3.50 for 5 oz. of the same stuff (Bibb) and that might last a week. So, the light runs you $9.90 a month or you can buy from the store for $14.00 per month. My lettuce has never suffered a recall either, because of e-coli or salmonella. Anyway I get both sides. Thanks for reading and come back soon.

  2. I agreed with Nelly that the technical numbers ran together a bit in my head but I can see where that would really appeal to those technically-oriented folks. My focus was on the cost per month side. At first it does seem high but your comments clarify the balance of what I am paying in the store – especially when buying organic – with what my costs would be at home. Plus the assurance of knowing exactly what was or was not used in the growing process. I have someone to pass this on to who will really enjoy the numbers!

    • Hey Jackie,
      I guess the wattage and such is what you are referring to, but it can really make a difference in how the plant responds. Of course you can always just ask me what to use. Thanks for the visit.

  3. Hi ” UNK ” ,
    I love gardening as well . I take it you use a greenhouse ? I just do mine when the time and season appears . But I will take fresh grown veggies any day compared to having to but out of grocery stores . keep up the good work !
    i found your website very easy to read , it was presented well and great information with links and images as well .

    • Hi Brenda. Thanks for the comment. I do not use a greenhouse, I’m using what used to be a garden tool shed. I’m clearing space now to put a hybrid greenhouse, meaning it will use sun at times but will also utilize artificial lighting as well. For me, part of the fun, is growing vegetables in climates they are not supposed to grow in, during seasons they don’t normally thrive in.

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