We grow cacti indoors due to the weather (UK).

What should we look for when selecting lights? We have had mixed results with a new lighting system and have started to lose some.

See one of the old guys clearly dying/dead and my precious Euphorbia Obesa beginning to bolt

See one of the old guys clearly dying/dead and my precious Euphorbia Obesa beginning to bolt

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    @kevinsky - To start with we had two of these but they were expensive in electricity and one of them died within a few months. We couldn't find a replacement. We've recently tried an aquarium strip light but that seems not to be too effective as some of the cacti are beginning to look pale. Commented Sep 16, 2014 at 20:11
  • Nice collection. What direction is the window facing?
    – J. Musser
    Commented Sep 17, 2014 at 0:07
  • Doesn't matter much - trees block out much of the light - but it's north east ish. Commented Sep 17, 2014 at 0:14

1 Answer 1


With a north facing window in a northern climate you effectively have no outside light source as far as cacti are concerned. Your primary light source must be artificial and lots of it.

Check this answer. It's about moss but the light requirements are the same.

This gardener is having good luck indoors with "a 50W HID lamp (directly above this plant), and a 150W HQI lamp".

This question about growing chili peppers indoors is also relevant.

To sum up, you need:

  • lots of light
  • positioned close to the plants
  • if you use HID lights you will probably need a fan to distribute the heat
  • a mixture of HID, fluorescent and high pressure sodium will work
  • be prepared for the electrical bills as the lights should be on about 16 hours a day
  • for HID or high pressure sodium they draw a considerable amount of power. Ensure that your household circuitry can take it.
  • cheapest and coolest solution is lots of fluorescents suspended twelve to eighteen inches from the plants but this will not match the light output of the other types
  • LED lights do not seem to provide enough illumination
  • LED lights can provide enough illumination, but from my perusal of the market, there are currently a lot of low light producing scam-rigs out there. Commented Sep 17, 2014 at 15:39

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