I know. You think I’ve come over all fork handles again. But this is Saturday Swot Shop, no light entertainment here. Only dusty chalk and chewed pencils.
Tomatoes like all plants need light to photosynthesize. But how much?
One of the measurements you may come across in reference to quantity of light is foot candles.
Foot candles?
- A foot candle is a quantity of light intensity. A standard/international candle or candela is placed in the centre and the light received within a 1 foot radius of the candle is measured.
Light intensity?
- The room that you are sat in reading this probably has a light intensity of 5-10 foot candles. A kitchen brightly light with florescent tubes up to 100 foot candles and a bright sunny summers day of the type that we were promised but didn’t get, up to 10,000 foot candles. On our overcast days we’ve probably been groping around trying to light the BBQ in no more than 1,000 foot candles.
You may need to shed some more foot candles on this?
- Yes or maybe some lux ?
Lux ?
- Lux is the metric measurement for light quantity. 1 foot candle = 10.764 lux, normally converted as 1 foot candle = 10 lux.
So 1 candle will produce 1 lumen per sq foot, at a centre distance of 1 foot . This is a foot candle.
And 1 candle will produce 1 lumen per sq meter, at a centre distance of 1 meter. This is a Lux.
Lumen?
- Lumen is the measurement of the amount of light given out by something; in the above example, 1 candle.
Light bulbs for example have lumen measurements. The light bulbs in today’s photos have lumen of 600 and 360.
Is there a chance we could bring the tomato back into the spotlight ?
- The connection is light intensity and photosynthesis .Tomato plants start to synthesize at around 200 foot candles and for normal growth, flowering and fruit setting they need a minimum of 500 preferably 1,000-2,000 foot candles of light.
Hmm, perhaps a long lie down in a foot candled exclusion zone and it might start to make some sense.
This Saturday Swot Shop has been a bit like a strobe light. One moment I feel I’ve the hang of how light is measured and the next I feel back in the dark again. If anyone can illuminate me further and make lighter work of explaining it than I’ve done ( and confirm the tomato requirements stats ) I promise to throw the switch on the lighting puns!
