1000 watt electric heater puts out the same heat as 1000 watts used in LED lighting. Go with the lights. At least they put out usable light that converts to heat when it hits the plant.

Steve

I think 1000W electric heater should put out a lot more heat than 1000W of LED lights. LED lights are famous for using most of their electricity for light rather than heat, unlike incandescent or CFL lights. They produce some heat, but should not be producing as much heat as the same wattage of heating element or non-LED lights.

it depends on the amount of space you have to heat and how many flourescent bulbs you use. MY LED puts out no heat at all, but CFL and incandescent buls do and worth using if you are using a lot, but in the end I do not know which of the two depending on how many bulbs you use would use more electricity. You would have to give us an amount of how many so we can calculate.

How can you say that LED lights put out no heat at all? That is not true. They produce less heat than CFL and incandecent because they use less wattage to achieve the same lumens but they, like any device using electricity produce heat.

Thanks all for the comments :)

Sry, but I cannot put a 1000W heater, that is too much :/

I have a LED bulb which has 9W (=60W because is A+ on the energy meter, I guess), has a brightness of cca 800 lumens (LM) and its day white color (4000K).

The greenhouse measurements are approximate 1,3m x 2m x 1,8 m. I plan to have the light turn on for 3-4 hrs a day, because we will have sunny days (I am planing to put the trees and the greenhouse outside in March), so I do not need some spectacular, just to keep the warmth on the level of cca 5-10 Celsius inside the greenhouse. The bottles with warm water is actually working too, very well, but I dont think thats enough.

4 LEDs of 6.5 watts each put out the same amount of heat as 2 CFL of 13 watts each as well as one 26 watt soldering iron. Heat is heat some of that heat will be in the visible light spectrum.

Steve

HighColdDesert :

1000W electric heater will produce 1000W of heat.

1000W (real electrical power, not equivalent value) LED lamp will produce about 900W heat and 100W light (since the LED bulb has around 10-12% efficiency)

Ken none of my LED lights are even warm to the touch, in fact cool. Maybe mine are a different type? NO clue. I know my CFL lights were so hot I could'nt unscrew them without waiting for a few minutes.

I am using the 48 inch long tubes with the equivilent of 32 watts, and no heat. The bulbs I use are 100 watt equivilent and I can unscrew those those afre they have been on for hours and they feel cool.

I wish I knew a type of LED tube that did give off heat and I would use those instead to give off some heat to help keep my sunroom warmer. I am not willing to rise the cost of my electric bill with regular flourescent ot CFL. Can anyone suggest LED that do give off heat to make a difference?

MIke)

eSilviu: 1000W (real electrical power, not equivalent value) LED lamp will
produce about 900W heat and 100W light (since the LED bulb has around
10-12% efficiency)

True to a point. But light is energy and so if it is not used by plants then it will convert to heat. All forms of energy will convert to heat since it is the most fundamental form of energy. Plants are notoriously inefficient at converting light to food. That is why they need such long hours of exposure to light. For all practical purposes 1000W of any light source is equal to 1000W of heat. That is how the physics works out.

tropicofcancer (6b SW-PA) :

you are right... I did not specified in what the 100W light energy will transform.

It will transform in whatever would 100W of light from any source (halogen, CFL, LED, sun) would transform (again mostly heat).

As a late add, I built my 'main' greenhouse just for my calamondin orange tree. It is now over 50 years old. It's bitter fruit makes for some mighty fine marmalade, while the peels can be soaked in grain alcohol. Reduced with simple syrup, it makes a superb arancello. Summertime in a glass.... Even though it occupies a place of sunny prominence in the greenhouse, even there, it looses a lot of leaves when brought inside for the winter.. Photoperiod also causes leaf drop.

Put a fan in there that will help. All those other methods I wouldn't waste time with.

Thank you all for your advice :) May I just ask if putting a electric heater (which is put on the floor) which has cca 400 W of energy is a good idea with the citruses?

I had some problems with it (citrus trees) in the last few weeks - the end of the branches were turning black/brownish so I had to prune them. But, the soil was wet/moist for too long so it might be because of that and because I was heating the soil with bottles with warm water (which were cold by morning and had mist on the bottles which apparently damped the soil and air even more. I have repotted the citruses in dry soil and the brown branches are not appearing any longer.

I am no longer warming the soil with bottles because of that, but I am curious if the heater will cause any moisture problem inside the greenhouse? Is opening the greenhouse plastic door enough to let the moisture out of the greenhouse and let the fresh air in? I thought about warming the greenhouse with the heater for only half an hour, maybe one hour top once a day.

A space heater would work but be careful of how you set it up. If anything, heat from that will dry the air out even more in your greenhouse like mines. Use fans as Matt suggested. That is a must for mine.

https://chilledgrowlights.com/education/do-led-grow-lights-produce-heat

I keep reading the title of this thread and hope someone comes up with the answer so I can put away my electric heater and let my citrus trees to provide their own necessary heat. If this works how will my trees know when they have enough heat so they don't cook them selves.

Steve

https://www.gardena.com/int/garden-life/garden-magazine/everything-you-have-always-wanted-to-know-about-citrus-trees-and-overwintering-them/