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Mr. Green

best supplemental light in greenhouse?

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Hi i grow serveral ethnobotanics: kratom, caapi, coca, iboga, chaliponga etc.

Right now i have a 400 watt ceramic metal halide burnng all day in combination with natural light set on a timer 18/6 wich also does this job in winter time. I isolated my greenhouse and have a electrical heater inside to keep temperature up year round.

My question is should i use HID light or better go for fluorescent?

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If power isn't much of a issue then High Pressure Sodium - HPS

High pressure sodium bulbs emit an orange-red glow. This band of light triggers hormones in plants to increase flowering/budding in plants. They are the best grow lights available for secondary or supplemental lighting (used in conjunction with natural sunlight). This is ideal for greenhouse growing applications.

Not only is this a great flowering light, it has two features that make it a more economical choice. Their average lifespan is twice that of metal halides, but after 18,000 hours of use, they will start to draw more electricity than their rated watts while gradually producing less light. HPS bulbs are very efficient. They produce up to 140 lumens per watt. Their disadvantage is they are deficient in the blue spectrum. If a gardener were to start a young plant under a HPS bulb, she/he would see impressive vertical growth. In fact, probably too impressive. Most plants would grow up thin and lanky and in no time you will have to prune your plant back before it grows into the light fixture. The exception to this is using HPS grow lights in a greenhouse or in conjunction another light source that emits light in the blue spectrum. Light sources that have a high output in the blue spectrum like sunlight and MH grow lights offset any stretching caused by HPS bulbs.

HPS (High Pressure Sodium) bulbs are the most efficient bulbs that are available for grow lights. They are high in the red and yellow parts of the light spectrum and low in the blue, this imitates the fall sun. Because of this spectrum some plants that are grown with HPS (High Pressure Sodium) lights will grow elongated and rather leggy, while many other plants are not affected by the limited light spectrum. For plants that normally bud and flower in the fall an HPS (High Pressure Sodium) is usually the light of choice because it's light spectrum promotes flower production.

There are color corrected HPS (High Pressure Sodium) bulbs (such as the Son Agro) available for improved growing with HPS (High Pressure Sodium) efficiency. These are designed specifically for indoor horticulture, and have a more balanced color spectrum.

HPS (High Pressure Sodium) bulbs are made out of a translucent ceramic arc tube containing a mixture of sodium, mercury and xenon gas. This arc tube is suspended in an outer glass shield (bulb). HPS (High Pressure Sodium) bulbs range in power from 35w to 1000w, with the 250w, 400w, 600w and 1000w being the most popular for horticulture use.

HPS (High Pressure Sodium) bulbs should be changed no later than 24 months from initial use. These bulbs (like the Metal Halides) also slowly lose their brightness over time, so to maintain proper light intensity the bulbs must be changed at the end of their rated life.

Edited by mac

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I'll second the HPS. They are the best choice for total (plant) usable lumen production for both the initial cost of the lamp, and the day to day electrical cost of the lamp. I'd recommend a 12 month bulb change over 24, but to each their own.

Outdoors you won't need to worry about light spectrum to any great extent.

-G-

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ditto on HID. greenhouses are generally somewhat tall, so fluoros pretty much suck. i have fluoros in my gh simply to give me light to see at night, nothing more.

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wow sounds like you have a great setup any pics and things must be growing like mad having the heater also... what type of heater are you using gas or power ???

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Brand new LED's being sold in Oz, 90Watt = to 400w, a heap more usable light. Inbuilt fan too cool. can get bigger and smaller, very little heat output. 60deg output is only downside. a shit load longer bulb life ;)

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