Hi, I have a relatively simple question when determining DLI range. At what part of the plant should I measure what my lighting should be? Should it be measured from the highest part of the plant? Pretty simple question at the end of the day but it would help me out a lot of someone could answer lol
To calculate dli properly you need an accurate ppfd average of your entire canopy. If you’re going to measure would require a series of measurements taken at same height all the way across your grow space in both directions.
To put it even more simply. If I have one singular plant, and I’m using an app such as the Photone app, where would I place the phone, near the soil, or at the top of the plant?
Even simply, that’s not really how it works.
Ppfd is the unit required to calculate dli. And that is umols per square meter per second. Lowering or raising your light (or changing the height at which you measure) doesn’t put more or less light into your grow space. It will just shorten or lengthen the pattern of light. Since the light will hit the plant in multiple areas at multiple different heights and the photons will bounce around until used by the plant, wasted as heat loss, or escaping the spave, you will never have an accurate dli if you don’t use a true ppfd average.
Should I measure my ppfd from the top of the plant or the bottom ?
Others have answered DLI, but also, consider heat issues.
Top of plant, will be affected by heat from lights from above, or lighting stress, limiting the maximum your plant will allow in her space (topside, VPD)
Lights being used?
Even more simple, don’t worry about DLI, make sure your light produces enough PPF for the space you are growing in. Set the hight so not to burn your plants and the DLI will be fine. It’s really only a limiting factor if you are growing outside or with underpowered lights.
If Dr. Photon says not to worry about it, that’s good enough for me
Well that’s what I’m trying to prevent kind of, so I should assume your ppfd will be calculated based off of the top of the plant
LEDs are not going to produce enough heat to burn your plant, but powerful lights can put out too much PPFD directly under them to do damage. If your light produces enough total PPF to support your grow area, set your light to manufactures recommend height or look for a 3rd party PAR map for your light. Keep it 1000 max directly under and the corners at least 500