Lately I have had lots of questions about how to increase yields and get the most out of a Click & Grow flower pot. As watering and fertilizing are taken care of (we have spent years on the "really best" programs), the most impressive effect can be achieved with hardcore lighting.
So what is the meanest lighting technology out there? I will put here a comparison table with luxes (light power in lumens per square-metre). Take a note, that the more light a plant will get, the faster it will grow. It is almost impossible to have too much light. For example commercial busy lizzy growers recommend at least 15 000 lux for 8 hrs a day. But this is hardcore.
The sun. On a clear day this yellow fellow boosts out from 35 000 to 130 000 lx. That is more than enough.
A clear day without direct sunlight. 10 000 to 20 000 lux. Everything will grow with this amount of light too.
Overcast day 1000 lux. Plants are not growing ultra-fast, but they are ok.
320-500 lx common office artificial lighting. This is the minimum for germination also. Plants will grow, but they would grow a dozen times faster in direct sunlight.
50 lx is a dark living room environment away from windows. This is seriously too little.
So what can be achieved with lamps? A high-pressure sodium (HPS, the commercial grow lights used in greenhouses with orange looking light) can deliver about 120 lm per Watt. Meaning that if a 200W HPS is projected to a surface of 1x1 m, the light intensity will reach 24 000 lx. This is quite hardcore. But even more can be achieved...
Take a 800W HPS and project it somehow on a even smaller surface. Lets say 50 x 50 cm. Intensity will reach 384 000 lx. Beats the sun :) I'll eat my gardening gloves if you don't see the plants grow larger with matter of minutes.
But it's not all roses - temperatures will increase together with every HPS watt used. So a overclocked gardener must take care of that.
Lately much can be achieved with red and blue plant growing leds. Sadly, monochrome led power can not be accurately expressed in lumens and they can't be compared here. But a 90W led won't definitely do any harm :)
The cheaper option would be the use of fluorescent lights (energy saving bulbs and office lighting). Delivering a little less than 90 lm/w, a 20 W saving bulb can provide a plant with 28 800 lux when projected on an area of 25 x 25 cm (a Click and Grow pot for example). This by the way is more light than required for commercial cucumber growing.