Advanced GrowingGrow Lights

Yield Boosters: Vertical Lighting for cannabis, Heath Robinson

Yield Boosters: Vertical Lighting for cannabis


Vertical Lighting for cannabis Heath Robinson. Want to push the envelope? Bust open your boundaries? Top your personal best? Okay, so you might have nodded ‘yeah yeah’ to that string of rhetoric – but in this section, we’re going to actually show you how to do it.


First up, we’re going to take a look at “vertical lighting grow room” – what it is, how to go about it, and why thinking like a Martian can be quite helpful.

Vertical Lighting for cannabis Heath Robinson

WORDS: Heath R

Vertical Lighting for cannabis Heath Robinson
Vertical Lighting for cannabis Heath Robinson

Growing indoors is totally different from growing outdoors. Ok, so plants still need to be fed and watered so that they photosynthesize, grow and bloom, but there’s one important factor that’s fundamentally changed. The Sun! It may sound mind-numbingly obvious but it’s a fact that’s really worth exploring further: the biggest difference between growing indoors and outdoors is LIGHT.

We still need light, of course, and many indoor gardeners use grow lamps to produce it artificially.

However, if you are growing plants that require high light levels (warm season vegetables such as cucumbers and tomatoes or exotic palms, herbs or cacti) are your grow lamps really going to cut the mustard? Granted, grow lamps are bright (very bright!) and, like the Sun, it’s a bad idea to stare at them! But we should really end the comparisons there.


A 1,000W grow lamp compared to the Sun? Are you kidding me? Can you hear that? It’s God laughing. I mean, when you look at the stats, it’s not really a fair comparison. Can you imagine a grow lamp that’s over a million times the size of Earth? Hmmm … that’s beyond my visualization skills … but despite the huge physical differences between a regular grow lamp and the Sun, it’s still all too tempting to think of our grow lamps as direct replacements, hang them above our plants, and expect them to do exactly the same job.


  • Pedantic scientists claim that the inside of the Sun is completely dark. It’s only the Sun’s outer surface that shines brightly.
  • The surface of the sun is about 10,000° Fahrenheit (5,500° Celsius).
  • Despite being dark, the center of the sun is a lot warmer than the surface: 27 million °F (15 million °C) (some might even say that’s a little on the hot side).
  • Light from the Sun takes eight minutes to travel 93 million miles in order to reach us; it takes another half an hour to reach Jupiter and seven hours to reach the edge of the Solar System.
  • Just like how planets orbit around the Sun, the Sun orbits around the center of the Milky Way galaxy, taking 225,000,000 years to complete a full orbit, traveling at 800,000 kilometers per hour. Hold on to your seats!
  • The Sun weighs 1,989,000,000,000,000,000,000,000,000,000 kilograms! That’s about 4,384,994,390,000,000,000,000,000,000,000 pounds. Ahem, I think somebody indulged too many extra large fries…
  • … not surprising then: the Sun is actually on a diet. Every time hydrogen nuclei fuse together to form helium nuclei, which results in a burst of energy, heating up and powering the Sun, it loses a tiny amount of its mass … about 4 million tons a second.
  • … but despite decreasing in mass, the Sun will eventually increase in size to the point where it completely engulfs the Earth (and other inner planets) before collapsing into nothing … well nearly nothing … a very small “White Dwarf.” Sobering thoughts indeed.
  • The Sun is nearly half-way through its life, and is running pretty well at the moment. However it is no longer under warranty and is due for its 5 billion year service pretty soon.

Consider the usual application and positioning of a High Intensity Discharge grow lamp. Usually it is placed overhead just a few feet above the top of the plants. A reflector is used to direct the light downwards. A really important fact to note is that some parts of the plant will be twice or three times the distance from the grow lamp as other parts.


Have you stopped to consider how much less energy the lower parts of your plants are receiving than the tops? Remember, your grow lamps are nothing like the Sun. Outdoors, an extra few feet between the top and bottom of a plant is no big deal as far as the Sun is concerned… I mean, it’s already travelled 93 million miles to get here! I think the Sun can stretch to an extra few feet.


But an extra few feet to your grow lamp is a different story. Relatively speaking, if we were twice the distance from the Sun, it would be like we were suddenly on a different planet – one reason why Martian summers are so crappy.

Grow Lamps and the Sweet Zone

So what’s the solution? Knowing how quickly the precious light from your humble grow lamps diminishes in strength, it would seem that the name of the game is to get your plants as close to your grow lamps as possible. But, of course, grow lamps radiate heat so they always need to be kept a safe distance away from your plants – otherwise you’ll end up with a lot of crispy dead leaves!


If you place the back of your hand near to a grow lamp when it is switched on (being careful not to actually touch the grow lamp!) you can physically feel the heat it gives off. If you leave your hand there for a while it will soon start to feel uncomfortably warm. If any part of your plant resides in this zone it will most likely start to show signs of heat burn. The safe and comfortable distance from a grow lamp depends on wattage, plant variety, and other environmental factors.


Ideally, you should invest in a light meter. If you don’t have one, then one approach is to use the back of your hand as a very approximate measure – you should not be able to feel a definite and gradually increasing warmth. Admittedly, this is far from a scientific approach, but at least it’s a real world rule of thumb that’s served me fine over the years. The closest point to the lamp that qualifies this test is roughly the optimum distance from the grow lamp. In other words: it’s as close as possible but not too close!


This point is often referred to by experienced indoor gardeners as the “sweet zone” – so named because it is in this area that the most vigorous growth and bloom is often to be found. Trouble is … if you’re hanging your grow lamps above your plants at this safe distance, only the very tops of your plants enjoy it! Anything lower down gets exponentially less light.


Growers have devised a myriad of strategies to ensure that as much of the plant as possible basks in this “sweet zone.” Some growers bend, prune and train their plants indoors to form wider canopies (and thus increase the proportion of the plant in the ‘sweet zone’). Others take a far more radical approach and place grow lamps at the sides of their plants.

Supplemental Side Lighting

Supplemental side lighting is the technique of adding grow lamps in order to light the sides of the plants. Some growers use banks of T5 florescent tubes (which can be placed closer to plants than HID lamps). Other indoor gardeners use an additional HID grow lamp positioned adjacent to the plants at 90 degrees to the lamp above.


The result is increased fruit and flower development across the entire height of the plant. When adding lights in this way, you may well need to increase air-flow so that adequate levels of CO2 are maintained and the temperatures inside your indoor garden do not become excessive.

Techniques Using Small Plants

One response to the waning levels of incident energy from grow lamps over distance is to produce smaller plants. Many indoor gardeners prefer to grow larger numbers of small plants in vertical growth chambers. Vertical growth chambers tend to dispense with reflectors all together. Instead the grow lamps are positioned at the center of the indoor garden, sometimes in a ventilated glass cool tube to help keep temperatures within optimal levels.


The main task of the ‘chamber’ is to house lots of small plants on its inner edges so that they face inwards towards the central grow lamp fixture(s). This is a far more energy-efficient method of indoor gardening as plants are arrayed 360 degrees around the grow lamp – meaning that a greater surface area enjoys optimum light levels.

Techniques Using Larger Plants

Indoor gardeners who prefer to grow larger plants can array them in rows about two and a half to three feet apart. A reflector-less bulb, hung vertically, can be placed in between each row. It therefore lights the sides of two plants at once! If using 1,000 watt lamps, consider using a light rail to move the lamp up and down in between the rows.


Position the lamp level with the mid-height of the plants. Now the whole side portion of each plant is being lit directly by the grow lamp. Additional support and wires may well be necessary to contain and train lateral plant growth so that foliage does not encroach upon the lamp.

Food for Thought

Side lighting allows you to light more of your plant, the whole length of it rather than just the canopy. This will ultimately result in more growth and more bloom so be sure that you have allotted enough space to accommodate it!


I hope that this inspires you to try alternative lighting strategies in your indoor garden. If you have any questions or further advice, please share your thoughts below!


One Comment

  1. I recall a grow you rolled a homade ebb and grow with 4 600s hung vertically. Looked as i recall like an olympic ring. At least thats what i recall. If this sparks a recALL event would love to see if you could dig it out of the archives. I was telling a guy about it but cand find the pics online anylonger.

Leave a Reply

Your email address will not be published. Required fields are marked *

The maximum upload file size: 1 MB.
You can upload: image, video.
Links to YouTube, Facebook, Twitter and other services inserted in the comment text will be automatically embedded.

Related Articles

Back to top button