PPFD Test of Household Bulbs, Ikea 10W Grow Bulb, and T5 (28W) CFL Fixture
We’re back again with another, more thorough, household bulb test. We’re testing 2.2W, 5.7W, 10W (Ikea PAR30 Grow Light) LED bulbs as well as a 2x14W T5 (CFL) fixture. Here's our first LED bulb PPFD test. The goal with the test is to see how much light (photons) these bulbs put at certain heights, how large their light footprint is and if or when they are a good choice for indoor growing (answer: in certain scenarios, yes, they are a decent option for (small) small scale grows).
Here are two of the bulbs we tested to give you an idea of what's coming:
As we discussed in previous blogs and videos, we know that all plants require a certain amount of photons (light intensity) to grow and prosper. Fruit-bearing plants, including cannabis, need higher light intensities than small vegetable plants or decoration plants. If you haven’t already, familiarize yourself with the concept of DLI (Daily Light Integral) and PPFD to fully understand how much light various plants want and for how long they want to be exposed:
LEDTonic's DLI (Daily Light Integral) & PPFD Instructions for Plants and Vegetables
We see a lot of growers out there use all kinds of lamps and bulbs to illuminate their plants. In some cases, the results and yields are excellent. In other cases, we see the opposite. We believe that poor results are often due to limited information about a certain lamp’s performance or light output. A common way of thinking is that “I’ll try this/these lamps for my grow and see how it works out. If I don’t get the results I’m hoping for, I’ll upgrade my setup later on.”
A completely reasonable and logical way of thinking if there are no data or spec sheets to use. That’s, however, why we’re here. We have the tools (MQ-500 quantum sensor) and equipment to measure how lamps perform and how intense light (PPFD) they produce on certain spots and at certain heights.
We also made so-called “PPFD light footprint maps” where we note down what intensity in umol/m2/s the tested bulbs produce. Having this information will tell us what plants can successfully be grown under which bulbs.
Keep in mind that these bulbs are general household bulbs and not intended for growing. In certain cases, they work well for small scale grows but the bulbs are generally not built to last for years or to run as efficiently as possible. LED grow lights that are specifically designed for indoor growing will often last 50.000+ hours, have a better optimized light color spectrum, and run more efficiently (less electricity consumed per emitted photon). Still, if you’re a hobby grower or just starting out with indoor growing on a budget, everyday E27 bulbs (or similar sockets) can get the job done.
We have not taken the bulbs apart to test and measure their drivers or diodes. It’s likely that a known brand like Philips will have a bit better hardware than generic brands. Better hardware makes for a potentially longer-lasting or better-performing lamp.
Without further ado, here are the light footprint maps of the tested bulbs, all values are in umol/m2/s (PPFD).
28W T5 CFL
2.2W LED Bulb
5.7W LED Bulb (with focusing lenses)
5.7W LED Bulb (without focusing lenses)
10W Ikea LED Grow Bulb
As we discuss in the video, the 28W T5 CFL is putting out very, very limited amount of light. To the naked eye, it might look plentiful but when we actually measure it, we clearly see that it’s far from enough to properly illuminate most indoor grown plants. Not only does this fixture produce fewer photons per watt, but it is also extremely poor at funnelling the photons to where they are needed; underneath the lamp, at the plants’ canopies. Compared to LED lamps, this fixture emits light evenly in all directions - up, down, right, left. As the emitted light is radiating in all directions from the T5 tube, the lamp’s rated lumen is high (2280 lm) but this value is rather misleading. As only a portion of the emitted light is projected in the “correct” direction (towards the plants), the total lumen output does not give a fair picture of how much “useful” light the lamp produces, i.e. how many of the photons actually land on the plants.
The 2.2W LED bulb with 36-degree lenses gives a very small light footprint but if growing only one single plant, a small basil with 4” (10cm) diameter width, it will perform okay. At about 5” (12.5 cm) distance from the canopy it delivers 300 PPFD center spot and 100 PPFD in the outer edges, resulting in 200 PPFD average. At a distance four times greater compared to the T5 fixture (1” height), it produces over 2x center spot intensity, despite only being rated at 140 lumens. If the goal is to illuminate one small plant, the 2.2W LED is a better option than 28W T5.
The 5.7W LED bulb with 36-degree lenses can be used effectively between 11” and 14” height from canopy level. At 11”, we see 590 PPFD and at 14” we see 368 PPFD in the center spot. 368 PPFD will work great for plants that require a half sun or partly shaded environment, with an intensity of 100 PPF in the outer edges of a 6” (15cm) diameter area. Hanging the bulb at 11” will instead produce a center intensity of 590 PPFD while still having the same reach and produce 100 PPFD in the outer edges of a 6” (15cm) diameter area, perfect for small high-light plants. This bulb could be used at shorter distances from canopy but the center spot intensity would be over 600 PPFD and only suitable for plants requiring very high intensity, such as a high-light succulent or possibly a bonsai version of a fruiting/flowering plant.
The 10W Ikea LED bulb is useful between 10” (25cm) and 18” (45cm). Between these heights, the center spot intensity varies from 150 PPFD to 600 PPFD. For cultivating seedlings, the lamp performs well at a distance of 18” and it will cover a 10” (25cm) diameter area. For young-adult plants and plants in early vegetative state, 250 PPFD is a good intensity. At 14” height it will cover an 8” (20cm) diameter area with this intensity. At a 10” distance between lamp and canopy, it produces 600 PPFD center spot and 100 PPFD in the outer edges of a 9” (23cm) diameter area. This would be suitable for a fruiting plant such as pepper or tomato, with an 8-9" (20-23cm) diameter canopy.
It is quite easy to see that the IKEA bulb performs best of all the light sources in this test. While being quite good at what it is intended to do, grow plants, it is still only utilizing 10 watts of power. No matter how good a lamp is, 10 watts can only cover a limited area. There is always the option of using more lamps, but at some point, it becomes more practical to use bigger lamps instead of bulbs. While plugging in a bunch of small household bulbs may seem like a cheap alternative at first, these bulbs are not purely intended for growing. Aside from being less efficient at producing photons compared to "real" grow bulbs, they have quite poor thermal management as they are not designed to be used for up to 18 hours a day, seven days a week. This results in a shorter rated life and higher electricity cost compared to a lamp made for growing. As we mentioned above, using household LED bulbs for indoor growing can work with okay results but to fully satisfy plants and get the biggest possible yields, in the long run, it will be more cost-effective to use a proper LED grow light, especially if growing more than one or a few small plants.