Test 1: Greens.
Note: This test was pooched by a hardware failure - LED light went bad. Please see Test 3: Greens for the rematch.
Constructed light isolation box for side-by-side growing (all same box, just rearranged):
Lights: 16 hours/day.
- 16W triband LED spotlight, 3rd generation (132 red - 18 blue - 18 full spectrum white LEDs, about 7:1:1)
- 15W 6500 K CFL floodlight, 650 lumens, "daylight" bulb with built-in reflector.
Today I found a CFL flood that was 16W... oh, well, 15W is close enough, I'm not going to buy more bulbs. For comparison, AG Deluxe bulbs are 26W, but unfocused. They also seem yellower to my eye.
The CFL is definitely hotter. Which will probably give the CFL plants a head start.
2009-01-23: Presoaked a couple hours and planted seeds in each of two pots:
- 4 French blush radish (thin to 1 or 2) - harvest time 25 days
- 3 baby leaf spinach (all others thin to 1) - harvest 30-45 days
- 3 tendergreen mustard - harvest 30 days
- 3 little Caesar romaine - harvest 45-60 days
In 9.4" diameter Misco self-watering pots (Walmart plant spa), and fresh Miracle Gro potting mix.
Hypothesis: My best guess :
- There is enough light to grow all 4 species, if somewhat anemically.
- There will be < 10% difference in harvest.
What I want is > 10% difference in harvest - LEDs clearly more grow power for same watts.
Anyone else want to bet?
day 2: Most mustard greens and half the lettuces up. No real difference CFL/LED.
day 3: Three radishes up, both pots. One LED lettuce still MIA. Unfortunately both missing sprouts on the LED side are the ones centerward. All mustard up. No spinach yet.
day 4: Moved 1 outside lettuce into the light on LED side. Only 2 of 3 sprouted. Radishes have same problem - missing the seedling in the light. But I don't think radishes would transplant well.
day 6: Set some spinach seed to germinate in wet paper towels in a baggie. Will use some of those if the ones in pots fail to come up. (Not unusual for spinach.)
day 7: Final radish seeds germinated, one each side. (Not unusual for radish.)
day 11: Still no sign of the original spinaches. Planted 6 more from baggie sproutings, most advanced centerward.
day 14: First spinach emerged, one on each side (baggie sproutings).
day 20&21: Two more spinach emerged (first CFL side with no leaves, 2nd LED side looking good).
day 5: Raised only LED light over greens. The spotlight was too concentrated in the center of the pot, with seedlings around the outside visibly stretching toward the light. CFL is not as focused, so raising it would entail a lot less light density at pot surface.
day 7: Lowered the LED back a bit. Maybe 3" higher than CFL now. The LED plants are stretched enough that they can lean into the light circle if they want.
day 8-11: LED side brassicas keeling over. At first just one dark-side radish, but now 2 radishes and a mustard are lying down. Too leggy. The centermost radish (late sprouter in fullest light) is already taller than its CFL counterpart, and behind in leaf development. Best-lit mustard doing OK, but lagging all 3 CFL mustards.
day 14: Thinned. Didn't bother to weigh them. CFL side obviously better by far more than 10% - on the greens experiment.
day 21: Harvested brassicas. It's early, but the radishes were done, and the CFL side mustard was overshadowing everything - there were no questions remaining there. Left the lettuce and spinaches... for the moment.