The winter is coming! Here in Stockholm, Sweden, on our Alaskan altitude it’s going to be long and dark as every winter here. However, this winter looks like we are going to deal with unusually high electricity prices.
What does it mean for us, crazy tropical plants growers? Do we need to light deprive our darlings?
I have done a simple setup with a cheap day light LED lamp, and it took me about 40USD and 10 minutes from taking it out of the box to ready to grow.
How much does it cost to use it?
If you know your electricity price it’s easy to calculate. Let’s go through my example and then you can do it for your own situation.
The LED lamp I got is 5 ft (150cm) long, so it covers three of my potted Plumeria, two Hawaiian Ti plants and a few smaller ones. It takes 50W of power, which is 0.05kW per hour. I run it on a timer from 9am to 11pm, making it 14 hours/day. Our electricity price quadrupled in August comparing to June, now being about 0.22USD per kWh.
The running cost for 14 hours a day for 30 days is:
0.05kW * 0.22USD * 14 hrs * 30 days = 4.62USD
So, it costs me 4.62USD per month to provide my sun loving plants with 14 hours of a good quality light every day. This is with our currently very high (for Sweden) electricity prices. Well, everything is telling that it will be even more expensive during the winter, but it feels like I still have some budget for this.
And the light is so strong that we don’t need to use any other light sources in that room… and even in the adjacent ones.
How good is this light for plants?
These are not so called special growing lights, which are extremely and unnecessary expensive. After many years of growing, I can tell that plants are doing very well under these simple LED lights. Already now, just after 2 weeks since I installed them, I can tell by such fast growing plants as Plumeria, – it works well! They stagnated a bit, when the days became shorter at the end of August and the sun going lower. After just two weeks under the lamp, I see a lot of new growth developing in a good speed and healthy green.
I could let the Plumeria go dormant, but our growing season is too short to do so. You can check my other post about them flowering in winter, indoors. I was using some other lamps back then, but it’s very similar light.
How to choose a correct lamp?
Start with the length you need. For our large window I took a 150cm (5 ft) long one. They are also available shorter: 60cm (2 ft), 90cm (3 ft), 120cm (4 ft) and a larger one of 170cm (5 3/5 ft).
The length defines the wattage, the power consumption. My 5 ft lamp uses 50W per hour. Smaller ones are using less, as you can see in the table down on this page.
You should know that these lamps come in three shades of white: warm white (3000K), neutral white (4000K) and cold white (6400K). The higher the temperature (K), the brighter white light it is.
It does feels counterintuitive to talk about warm white having lower temperature and cold white higher, but if you think about molten metal, it becomes natural. When you start heating a chunk of metal at first it gets red, then yellow… the more you heat it, the brighter it gets.
Why this color temperature is important?
It’s a common opinion that consumers prefer having warm white lights (3000K) in the living areas. While it’s a matter of preference and it’s not true for me personally, still the warm white lamps are the most common to be sold.
Plants, however, prefer colder white light spectrum. The sun light temperature is 5000K, so two other available lamps with 4000K and 6400K is closer to the natural sun light. From the experience, I can tell that both do well for the plants. Which one of two to choose is a meter of your taste. 6400K have rather bluish light and you might feel not very comfortable in it. 4000K resemble more of a sunny day. Also, green plants look actually green in it, without any unnatural hue. So, 4000K is my choice for lamps’ color temperature.
Where to buy lamps?
Below, I looked up same or similar lamps I’m using, sold on the major Amazon national sites. You can choose your country, or closest one to you, and check those lamps.
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I was surprised to get this email but so glad that I did. I live in south Florida so these are not needed (unless growing indoors) but I found the information most interesting and helpful. Thank you!
Lucky you, you don’t need it! :)
Really glad it was helpful anyway. Thank you!
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