Moth worms all but destroyed the kale!
Geez, there is a scary similarity!!
Had the exact same problem this last couple of weeks! Kale was disappearing before my eyes! It was in pots under the verandah waiting to be planted out.
I'd get the grubs and there would be more the next day and more the day after that. My god those things can eat!
When they stopped on the kale because I put veggie dust on it, they decimated my Mint that was doing so well.
I have learned, everything has a bit of veggie dust now. it's only sulfur and some other natural compound I forget so not worried about it on the plants and it keeps those green eating machines away.
In suburbia I threw seeds in dirt or in my aeroponic system I made and stuff grew like no tomorrow. When I moved to this rural area I had I ideas of growing enough to do a farmers market once in a while just for the satisfaction of it.
Reality is I can barely get seedlings up and going out here. It's either too hot and kills them in a day or not hot enough and they get over watered and drowned or something else. Thought it was me till the next door neighbour with the big greenhouse and the netted patch complained during an over the fence conversation that his veggies were amounting to nothing this year and he didn't know why.
Thats why I set the old fridge up, more of a controlled environment.
Do you have a link for the LED'S?
I really need to put something down the sides of the fridge so they all get light. Haven't got much in it atm so it's OK but when I do add more I'm going to need more than a single light source.
As for the candles, I can't see them warming anything larger than my fridge and If I had LEDS in there, especially with the controller, the heat output from those would be more significant. I think one would need a LOT of those to make any difference to an outside greenhouse even big enough just to walk in. The burn time is a direct relationship to the heat output, more fuel consumed in a shorter time, the better the heat output. That candle while a clever enough idea to be sure, is basically a glorified match with the same heat output. Great for long term lighting but not for heating. A Tail light globe from a car would have far higher thermal output than that candle. One could do the maths on the thermodynamics but I'd be guessing its around 3-4W Maximum!
Pint of wax/shortening has less than 6 Kw of energy. He burned that over 120+ hours. Not a lot of power. First giveaway to me was he picked the jar up. Does not have to be too hot to touch to produce heat but if it's that cool...... Ya.
Maybe the candle Idea comes from people that think 4 tealights with an upside down flower pot will warm a room?
Placebos cure a lot of medical problems too I spose. Maybe someone should market "Warming Tablets" to these people. Take one and never be cold for 12 hours. Active ingredient, 100% chalk.
If you can get the shortening for free, then making a candle with a thicker wick or a bit of rope like sash cord would work better. Faster burn, much better heat. I'd Imagine unless you did them in a bucket you'd be having to do more every day but at least the greenhouse would stay warm.
A small smudge pot burner design running on veg oil I think would be a better alternative. Not something orchard sized but scaled down to where it gave enough heat for the job at hand without being over the top. Last one I did was a 4L saucepan with a 4" Pipe welded in the top and drilled for secondary air and 4x 1" holes in the lid for primary air.
With a 6ft flue that thing would throw enough heat to keep people back 4 ft and still had a jet flame out the top.
With the same 4L saucepan and something like a 1" flue/ secondary air mix chamber and a 1/2" primary air control that had a bit of metal over the top that could be moved to regulate it, You could tune the thing to do the sort of output needed for a greenhouse.
An electronics Boffin like yourself could probably use a small carburetor off something like a chainsaw linked to an arduino for primary air control. Set the " Idle " on the carb to allow enough air to keep the heater just going and link the arduino to a thermostat.
When the greenhouse cools off, arduino uses a servo to open the carb ( just want the carb for an accurate air metering) allowing more air and greater heat. When it's warm enough, the carb closes off the air and the thing idles.
All the fuel oil is in the pot. There is NO need to drip feed like you see on a lot of designs. It works just perfect in batch mode. All you need to do is control the primary air and it burns just fine. Refill and Light at night and shut off in the morning. If the servo could be set to hold an idle air setting, It could close the burner off all together when a set temp was reached or exceeded for a time or a CDS sensed it was daytime...... Or leave the thing burning all the time apart from top ups which you could do when lit if you had a cap on a refill port.
Haven't done anything with hydroponics but my aeroponics system made from a plastic drum, a fountain pump and a timer works a treat on Lettuce, rocket, Kale and similar leafy greens.