I have recently replaced one of the bulbs in my fluorescent, but when i plugged it in its a warm orange colour bulb yet the others are cool blue. I know the wattage is correct but whats the difference??
Any info would be much appreciated as i have some seedlings under it right now
Light bulbs of all types are rated and the Kelvin chart is used to display them.
When it comes to growing when a plant is in the vegetative growth phase it mostly wants the blue (bluish) light rays. Around 4500K the light rays begin to become blue and then deeper blue. 6500K is what many of the higher dollar HID MH bulbs are rated at and zillions of CFL’s and that is what people will veg with. When in the flowering phase of growth plants want more of the orange-reddish … hummm .. I never ate an orange radish before ….. so in that phase of growth bulbs rated roughly like 2000K to 2200 K are used. (This is mainly in MH & HPS lingo, both HID and CFL use the same color chart but there seems to be more variety in the CFL's so as it is said ... your mileage may vary ..... as might a particular Kelvin rating slightly vary depending on what type of lighting you use.
If the light that needed to be replaced put off a blue light it had to be in the 4500K range or higher, likely a good bit higher. I have to believe you could likely look at the other older remaining bulb, or at least I got the picture of a twin bulb setup based on what you said. But if so you should be able to find numbers on it and then match the numbers to a new bulb.
The question is how was the light being used, for vegging, for flowering, for both, for doing crossword puzzles underneath so you have good lighting to see all the shapes better?
What I am getting at is regardless of what Kelvin range bulb was there putting off the bluish light was that actually the right type of bulb to be using for how you use the light? If so, as in vegging, find the right bulb and replace the one you just got with it. Next would be regardless of how much light any light bulb of any sort appears to put off according to the human eye but it can seem a whole lot less light to a plant. Plants rely so heavily mainly on only two fairly tight ranges in the spectrum that as a bulb of any type is used it degrades and the more it is used the more degradation occurs, but the first sign most will ever get that the bulb is wearing out is when it stops working. Long before that it has become extremely inefficient and plants look well covered in light but to them they are just surviving in low light conditions. In other words if your use calls for a vegging/bluish Kelvin rated bulb then purchase two of the correct Kelvin range instead of only one so you then have two bulbs putting out as fully as they possibly can rather than one putting out all it can and the other that looks as bright maybe only putting out 10% or 20% of what it used to put out.
If by chance the light is used to keep donor/mother plants happy a mix/combination of Kelvin ranges works well for that so depending on if that is the use you might have stumbled into something better …. but I would still suggest changing the other bulb too so you have two fresh bulbs going.
Not a very detailed chart but it gives someone the basic idea.
