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[Lesson In Lamps] Hanging Heights (Part 1 of 3)

[Lesson In Lamps] Hanging Heights (Part 1 of 3)

The way you hang lamps affects your intensity, coverage area and overall growth. It's important that you get it right.

This is part 1 of a 3 part series

Here you'll learn how high to hang your lamps.

How to Hang

Your exact hanging height depends on the fooprint of your reflector. 

Hang it too high...

Hang your lamp too high, and three things will happen:

Hanging Heights LampsHanging Heights Lamps

1. Your footprint widens, and lots of light is lost to walls

Hanging Heights LampsHanging Heights Lamps

2. Your intensity drops too low, as light is spread out over a wider footprint.

Hanging Heights LampsHanging Heights Lamps

3. Your grow room becomes too cold - in winter, this isn't what you want. 

Hang it too low...

Hanging Heights LampsHanging Heights Lamps

1. Your footprint is too small and doesn't cover your entire tent.

Hanging Heights LampsHanging Heights Lamps

2.  Where there is light, your intensity is too much for plants to cope with.

Hanging Heights LampsHanging Heights Lamps

3. Your grow room grows too hot and you scorch your canopy layer.

Buy a Digital Ballast - you can dim and boost your intensity without moving lights up or down. This means you aren't messing with your footprint. 

Recommended hanging heights

Your exact height depends on:

  • Your reflector footprint
  •  Number of lights
  • Your tent size & shape
  • The plants you're growing

But as a general rule, here's how much of a gap you should leave between plants and your lamp

HID Lamps

HID lamps (HPS & MH) are very high intense, to make sure you don't burn plants, you need to leave a safe gap between your plants and canopy.

   Propagator Small Plant Medium Plant Large Plant
240W Lamp 140cm    90cm  60cm
400W Lamp 160cm    120cm  60cm
600W Lamp    150cm  120cm  70cm
750W Lamp        
1000W Lamp    160cm  140cm  90cm 

You can propagate under any size light. If doing this:

  • Position your propagator off centre
  • Make sure you leave a 150cm gap between the top of your propagator and bottom of your reflector (600W and 1000W lamps)
250W Lamp250W Lamp
400W Lamp400W Lamp
600W Lamp600W Lamp
1000W Lamp1000W Lamp
600W Lamp for Propagation600W Lamp for Propagation

Propagation Lamps

You only really want to use propagaton lights for cuttings, seedlings and mother plants. 

   Propagator Young Plants Mother plants
125W CFL 80cm    
Exolux Pro T5 - Single Tube (24W) directly over 60cm  60cm
Fluorescent Tube - 2 Tube (2 x 24W)  80cm    
Fluorescent Tube - 4 Tube (4 x 54W)      
Fluorescent Tube - 8 Tube (8 x 54W)      
Bright-Wing  - 2 Tube (110W) 80cm 50cm  30cm
Bright-Wing - 4 Tube (220W) 110cm 80cm  60cm

Choice of reflector

Your choice of reflector has a big impact on your hanging height - it's repsonsible for your light footprint.

The higher you go, the narrower your reflector should be. The lower you go, the wider it should be. 

Just look at the Adjust-A-Wings reflector - you can adjust your wing position to suit your hanging height


Wing setting: narrow
Distance: 45 – 60cm


Wing setting: wide
Distance: 25 - 35cm


Wing setting: medium
Distance: 40 - 50cm

About the author

Ian's our Sheffield shop manager. He loves tinkering in the greenhouse. Drop by to see what he's growing.

GroWell Hydroponics Sheffield

Call GroWell Sheffield:
0114 243 9242

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