Which Light! What is a vegetive light? What is full spectrum? What does 2k mean? Is there a light that puts out a SUN spectrum? These are all questions we are asked every day!
Starting out novice or upgrading your gardens primary light source? There has never been so much choice and it is easy to become confused or even overwhelmed by industry jargon and the endless technical information. Don’t ask the question “which is the best light” but rather which is the best light for you! From clones and seedlings, vegetive growth, early bloom, peak flower and ripening there are endless recommendations by industry professionals that often incorporate different primary and supplemental light strategies to achieve a desired finished spectrum. To the best of my knowledge there are few single light sources that can achieve perfect light spectrum at all stages of plant development and I put emphasis on perfect! So where does this leave the everyday grower!
Here are a few guidelines to remember.
In vegetive growth use light rated 6k or similar (Blue Light)
In bloom use light rated 2k or similar. (Red Light)
If using one bulb entire cultivation period then 4k balanced. (Yellow/Green)
Standard Single ended bulbs and bat wing shades.
1.0 x 1.0 Tents use 250 Veg /400/600-watt Bloom
1.2 x 1.2 Tents use 400 Veg/600 Bloom
1.5 x 1.5 Tents use 1000 watt
1.2 x 2.4 Tents use 3 x 400 watt Veg 3 x 600-watt Bloom or 2 x 600 & 1 x 400 watt
2.4 x 2.4 Tents use 4 x 600 watt
Double ended bulbs and/or batwing/ wide shades. (Gavita) etc.
1.2 x 1.2 Tents use 1 600/750/825 Fixture
1.5 x 1.5 Tents use 1 1000/1125 Fixture with wide shade or batwing.
1.2 x 2.4 Tents use 2 x 600/750/825 Fixtures with wide shades or batwings. If using more focused light shades (original gavita shades) then use 3 x Fixtures 600/750/825
2.4 x 2.4 Tents use 4 x 600/750/825 Fixtures.
LED Technology
Refer to LED replacement recommendations. Ie 600-watt LED replaces 1000 watt HID etc.
As LED technology increases at a hectic rate and older inferior models over many manufactures are outdated, we will focus on Lumatek and Pro Grow models which are popular at the present time. We will steer clear of DIY fixtures for the time being as we believe growers should have an intermediate to advanced understanding of light science before customizing their light schedule. It is important to note that when providing grower support to customers incorporating high end LED customization, we use both PAR meters/Spectrometers and decades of hands on experience regarding LED technology. Basically, LED technology has evolved at a hectic rate and in our view todays LED lighting delivers results that were only promised but not delivered by previous decades LED manufacturer’s.
We previously said “To the best of our knowledge there are few single light sources that can achieve perfect light spectrum at all stages of plant development.” Lumigrow LED fixtures may have been a close exemption to the rule. These fixtures enabled the grower to adjust the 2-4-6 K spectrums (not just total output) manually to achieve desired spectrum but efficiency compared to todays LED Technology is very low. What we mean by efficiency is the amount of light per watt that the fixtures produced. These fixtures were pricey to say the least costing more ten years ago than todays latest technology.
When implementing LED lighting always consider the final spectrum and how it will drive your garden. Full Spectrum LED means that all the plants light requirements are met at all stages of plant development. Vegetive and Bloom stages are covered adequately but the scientific high achiever may like to focus on more blue or red spectrums depending on plants developmental stage. For example, differing manufacturers may promote a light spectrum as 3500k with Reds which means an average light spectrum of 3500k or not quite 4k but far from 6k and with reds to promote flowering. This light would be capable of vegetive growth but is more focused on the flowering spectrum with the implementation of a separate red diodes to promote heavier flowering. The same fixture with blue diodes would be more focused on Vegetive growth. To the naked human eye many of todays LED’s have 90+ cri (color rendering index) or simply look white light and noticeable red or blue diodes for added stage specific performance. The blue/red or BLURPLE effect common in the original LED fixtures are in my opinion are more focused on specific targeted spectrums. They often don’t have as high efficiency but adequate none the less.
Any similarity between actual customer experience and examples are merely coincidental and for educational purposes only.
Bills Garden!
Bill is new to indoor gardening and has informed me upon entering the shop that he has done his research and a mate has given him some sound advice so he won’t be needing any assistance with his shopping experience. Two hours later……! Bill has purchased a 1.2 x 1.2 grow tent with necessary bits and pieces and chosen a 400-watt HPS magnetic ballast and 400-watt son-t-agro bulb. Upon leaving he comments how his seedlings are going to love his new set-up and can’t wait to get started. “Are you starting with that light are you” I ask and Bill and Bill replies “Bloody oath mate and I will move them into a big tent when they are ready to flower”. “Big tent! How big” I ask. Bill replies “it’s a 1.5 x 1.5. “What with that light” I ask. Bill replies sheepishly “Yeah mate WHY”?
Bill should of chose a smaller and more blue light to raise his garden and a larger wattage light in same spectrum he chose to flower under if he wants to use a larger tent. Here’s why!
A 400 watt Son-t-agro is very focused on red or 2K. As well as being to red for seedling growth it is also lots of light for seedlings and over kill. Bill will find his seedlings stretch under this light with longer internodal spacing producing a taller thinner looking plant. If bill used a 250/400 Metal halide or 6400K T5 flouro’s he would find his seedlings develop through this stage into the vegetive/pre- flower stage shorter, stockier with more internodal branching.
The 400-watt Son-t-agro is a good choice for flowering but way under sized for his 1.5 x 1.5 Flowering Tent. Bill will need a 1000-watt HPS or similarly a 600-watt LED replacement to adequately light his space. If Bill was to flower with his 400-watt light in this area it would be the equivalent to a plant constantly living in an overcast sun up or dawn /dusk environment outside for the duration of its existence. Very tall, thin and sparce or under developed flower density.
What did Bill do?
Bill put back his newly acquired set up and swapped it out for T5 flouro’s for seedling and early vegetive growth. A 1000 watt double ended ballast set-up with adjustable bat wing shade capable of dimming to 600 and increasing to 1150 watts. As the newer electronic ballast was able to operate both MH and HPS bulbs He implemented both a 6k metal halide lamp which covers him for late growth and a 2k lamp for flowering. Lamps for these types of ballasts were able to run 2-4-6-10 k bulbs. Bill did not need another tent setup but was told his plants would not grow in the big tent but would flower fine. Bill was misled.
We setup an identical light source and using a PAR meter were able to advise Bill of where he would set his ballast power.
