[Fishplate42]

Having grown all sorts of plants for decades without artificial light, is there a valid case for using modern grow lights as the energy consumption has been much reduced with the development of LED arrays? In the 'old days' grow lights created heat as well as light, now as the heat from LEDs is almost non-existent, is the energy saving negated by the need to heat the plants/soil by ancillary means?

Ralph.

[Yorkie]

The site owner, John, has written a couple of articles on the main website which you might find interesting:

https://www.allotment-garden.org/store/equipment/the-ultimate-heated-propagator

https://www.allotment-garden.org/garden-diary/6715/how-high-to-position-growlights/

[Fishplate42]

The site owner, John, has written a couple of articles on the main website which you might find interesting:

https://www.allotment-garden.org/store/equipment/the-ultimate-heated-propagator

https://www.allotment-garden.org/garden-diary/6715/how-high-to-position-growlights/

Thank you. I have read both those articles already, and they are about the benefits of using grow lights and using the modern systems. One of the selling points made by both manufactures and users alike is the energy saving by using LED lights over conventional lamps, which is true as far as producing the light. The reason LED lighting is so efficient is that it does not 'waste' energy producing excessive heat. My question is does the fact that with modern LED lights, you have to provide supplementary heating negate the saving made by using LED lighting?

Ralph

[New shoot]

Where are you intending on setting them up Fishplate?  You will need heat as well, but how much depends on what you want to do.

I use mine inside the house.  At the moment I have peppers, chillies and aubergines that have just been sown and they are sitting on a heated propagator base.  Once they are up, they usually rough it on windowsills with tinfoil reflectors behind them, but grow lights are useful for keeping stuff like this growing well without getting leggy.    My small grow light set up currently has onions under it.   I have a much bigger one on the way (fingers crossed - it was supposed to be a Christmas pressie) and am intending to put all these seedlings under it when it gets here as the house will be warm enough.  I could get by without it but I think OH would quite like not to have every window in the house lined with pots   

If you were using them outside in a greenhouse, you would have to heat something if you were growing tender stuff like this.  If heating the whole greenhouse would be too costly, you could set up a small area with the grow lights and an insulated tent-like affair around it, then a soil warming cable would probably do it.  There are others on here who use grow lights outside, so I will hand over to them for more detailed advice on that 

[Fishplate42]

Where are you intending on setting them up Fishplate?  You will need heat as well, but how much depends on what you want to do.

Thank you for your reply, I am not intending to use any grow lights (at least not at the moment  ) I was just pointing out that conventional (old style) grow lights will also supply heat. With LED lights you have to supply heat in addition to get the same conditions as were achieved before, so maybe the economy achieved is not as great as one might think.

I know how they are used and the advantages they can give. My question regarding the real economy was just a passing thought provoked by claims of economic energy use by suppliers and users that I have not seen discussed before.

Ralph

[al78]

It probably is if we are repeatedly going to get months of significant sunshine deficit like W Sussex has had from October to the present day.

[Nobbie]

Modern LEDs are still only about 50% efficient, so still generate heat. I use a 20W 30cm square array attached to the lid of one of those plastic storage boxes about 80*40*50cm. The LED still generates enough heat to keep  plants plenty warm up in the loft. I think with older style lights you needed ventilation to remove the excess heat.

[Subversive_plot]

I have a plant stand indoors, mostly for  growing orchids, but this year I'm also growing a little basil.

My lights are old-school fluorescent shop lights, but I will probably be changing those out for LED lights in the future.

I have heard of agricultural set-ups (yes, for FOOD, not other "crops') in some countries that are all indoors, all LED, but I have no information on the economics. I'm thinking this was in northern Europe, in short summer areas.

[AndyRVTR]

I was advised by a really serious chilli grower to buy a couple of 100w, 6500k led daylight bulbs to start with...  they use no electricity at all, only 12w each and no heat whatsoever. I didnt want to spend any silly money until I knew if I wanted to grow chillies seriously.. they seem to be working OK.

[hasbeans]

With LED lights you have to supply heat in addition to get the same conditions as were achieved before, so maybe the economy achieved is not as great as one might think.

I know how they are used and the advantages they can give. My question regarding the real economy was just a passing thought provoked by claims of economic energy use by suppliers and users that I have not seen discussed before.

Ralph

I've seen debate before about whether the move from filament was market driven more than efficiency - filaments had got so good that people weren't buying enough. 

I believe the gist was: 
Whether bulb efficiency was a problem with the global move or opportunity to move to renewable energy.  In other words electicity should be able to be very cheap anyhow
Was the heat from filaments benificial in homes in colder climates (your point about additional heat mats required)?  A suggestion was that the ideal would be led's in summer, filaments in winter.
Was the downside of led's worth the benefits?  THey are difficult to safely dispose of compared to filament due to the extra electronic components.

In short, you may have a point, except when you don't want the heat!

[Aidy]

I have been using them for a good few years now.
I have two LED units, a 12w unit and a 300w unit, the lower one is used for germination so when they pop up there is light.
The 300w unit is for growing on, mainly chillies but will add tommys in if required.
I will say the 300w does produced heat, it has a cooling fan and the unit is defo warm to the touch.

I would think technology has moved on a tad and probably a little better than my unit. One thing tho if growing peppers etc be careful not to give them too much light, I find 10-11 hours a day is more than enough, replicate their natural average light levels where they grow, for instance I use the average light level for the equator.

[Fishplate42]

Modern LEDs are still only about 50% efficient, so still generate heat. I use a 20W 30cm square array attached to the lid of one of those plastic storage boxes about 80*40*50cm. The LED still generates enough heat to keep  plants plenty warm up in the loft. I think with older style lights you needed ventilation to remove the excess heat.

That's interesting. What light(s) are you using and what temperature are you getting? Great idea growing them in the loft - That had not occurred to me, but it is the obvious place. I might be tempted to have a go - you never know, this old fud might have a go at something new!

Ralph

[Nobbie]

Modern LEDs are still only about 50% efficient, so still generate heat. I use a 20W 30cm square array attached to the lid of one of those plastic storage boxes about 80*40*50cm. The LED still generates enough heat to keep  plants plenty warm up in the loft. I think with older style lights you needed ventilation to remove the excess heat.

That's interesting. What light(s) are you using and what temperature are you getting? Great idea growing them in the loft - That had not occurred to me, but it is the obvious place. I might be tempted to have a go - you never know, this old fud might have a go at something new!

Ralph

I just checked and it was a 45w LED off eBay for under £20, they seem to be quoting the equivalent power in most of the adverts which isn’t very helpful.

https://www.ebay.co.uk/itm/363172843663

Not a recommendation for that particular one, it’s just been picked at random as there are hundreds of sellers.

Not sure on temps, but I do have to open the lid to stop it getting too hot when the light is on. It’s currently in a cupboard for convenience, but when up in the loft I put a timer on it so it comes on at night otherwise it might be too cold when temps dip overnight with the led off.

[Ema]

Just wanted to add that I like working with the seasons. Unless your growing something with a really long season I don’t think it’s worth the effort.

I also can’t see that veg like micro greens grown in someone’s spare bedroom under lights is any good for you.

[New shoot]

In my case, I love my house but it is old, with small windows and only half with decent light levels, so I find grow lights a great help.  At the moment there are just some onions growing under mine (silly big ones grown for fun), but long season, warm climate crops like aubergines, peppers and chillies are on the way and much easier to do with the lights.

I have tried micro-greens but tbh sprouting seeds like mung beans and lentils are easier and just need a jam jar on the windowsill