You need to figure it according to what kind of bulbs you have (fluorescent? CFL? LED?...); your use and the cost of electricity where you live. If you know (the info is on package and on bulbs) consumption in W/hour, multiply by hours used and multiply that by price/W...

Thanks Steven, very helpful. What would you recommend for getting the plants used to the light? Introduce for an hour first or is that too cautious?

Introducing plant to stronger light (more that it is used for) for an hour doesn't help. Plant should be put under lights, kept there and acclimatize to stronger light gradually over period of at least few days (if it was strong sunlight, I may be weeks).

If plants are going under the lights, start with bigger distance and lower the lights little every day or two. Consider how much heat your fixture emits (there is difference between various bulbs, just like consumption), and it may differ for different pants. I have many plants as close as 2" from the light source, but they started much further away. For others, that would be too close even if acclimatized.

Thanks Rina!

I spend around $250 per year on electricity for my 10 T5HO 4' grow lights. On top of that I spend around $40 for running my ventilation fans that keep things cool and air flowing around. 6 of these lights aren't run during the summer as I put a lot of my collection outside.

This is calculated using a spreadsheet for our local seasonal time of use electricity pricing, hours I run my lights, etc.

Probably your costs are MUCH lower than mine because I have 540W of lights plus fans.

Thanks ewwmayo, that really helps. Yes, my setup will be quite smaller so good to know it won't cost loads.

An additional question: I have very limited space so was considering either hanging the lights in the window where the plants are kept or moving them to a location in the house (a bit of a nook in the living room) where there's very little light and just using artificial light.

Any opinions on what is better? I was hoping to just use the grow lights to supplement natural light (about 8 hours worth and quite weak this time of year) by moving them under the lights when it gets dark but from Rina's reply that doesn't sound like a good idea.

It would be easiest to keep your plants in one place, in my opinion. If you put your lights by the window, make sure you can get them close enough to your plants or they will not do much.

My windows are terrible in the winter so by using lights I no longer rely on them.

Depends on if you want to have your plants stay okay for the winter or grow better and nicer (at higher cost). There are many approaches, each with benefits. =)

Whitney

I agree with eww, it is more economical to keep as many plants as possible together.

I think you may have misunderstand what I was saying. Lights can be set on timers, and they will go on and off for as many hours as you want, and at any time you set it for. Most of my succulents are in a basement, where there is no natural light - very small windows, and not close by. Plants are on shelves, and lights hanging above them. Right now, I have 'reversed' daytime with nighttime in order to save some $ on hydro (we pay less 50% less for kWh used during off-peak consumption, I do not know what you pay): timer will switch on at 6:30pm, and it will turn them off at 7:30am (you can set it for any time you want). It works well; plants get proper day & night - when lights are off, it is dark = night for the plants).

If you keep plants in living area, switching day for night will not work, as there is lot of natural light. Plants need to sleep too :) But you can put all of your plants in the niche you have and keep them under lights during normal day hours. It will cost more if you have many plants, but if using only one 4ft fixture, it shouldn't be that expensive. LED tubes are quite efficient and will cost less in hydro cost than CFL bulbs and considerably less if you were using incandescent lightbulbs.

If you have only few plants, you could carry them from one location to another - from window to under lights if you wish. It doesn't make sense to me since plants will get some (probably weak) light thru the window, and just few hours of stronger light (and in my case, I would have to move too many). If you want to keep plants in/on windows and light was weak, I would still put some lights over the plants, set them on timer and keep lights on for minimum 8hrs - JMO.

Thanks for the great advice Rina! Your setup sounds perfect for Canada. I was born and raised in Niagara Falls so know all too well how expensive hydro is! Luckily it's more reasonable in the UK.

Whitney

It has gone up and expected to increase even more -:( - I believe it is a problem everywhere. Currently, we pay .18/kWh on peak, and .08/kWh off peak...so if one was using approx. 300kWh in a month, difference in $ for electricity in my set up will be about $20-30/mo. (depending on type of light bulbs and exact times of day).

I run (6) T5H0 lights about 10-12 hours a day. Raised my electrical bill by about $20. I'll make that $ back when I can sell in spring. Just look up a energy cost calculator and figure out your area's kw/h rate.