I got 99 problems but light ain't one!
Dec 4, 2018 20:23:02 GMT -5
meizzwang, rmeyer, and 10 more like this
Post by calen on Dec 4, 2018 20:23:02 GMT -5
(Moved this over to P&C from the General Board, aka "where interesting threads go to die." The original thread centered around ways to test light quantity and quality in detail. I'd like this thread to be about other factors to consider if you're trying to ninja seedlings up to a large size quickly and I hope other experienced growers will also chime in with with more info! The gist of this post is that while there are about a thousand things that can happen to slow yo seedlings down, light isn't really one of them unless the light is REALLY bad. Or at least other things will be worse. Just put your plants under some bright bulbs and then pay extreme attention to everything else lol!)
As a practical matter, I judge light quality and quantity by how the plants look. Seedlings should display the same color tones and intensity as optimally grown mature plants, essentially. If the seedlings are looking bright and vibrant, that tells me all I need to know without necessarily involving various gadgets / the Large Hadron Collider, etc. When your seedlings are looking like pictures taken in meizzwang ‘s yard, you’re doing it right!
Certain circumstances can complicate this. For example, aggressive fertilization will cause the plants to green-up, mimicking under-lit conditions. When I see my seedlings green-up I know they are at the upper end of what they can tolerate nutrient-wise. It’s usually pretty easy to distinguish this from bad lighting because it has a sudden onset (1-2 weeks) whereas my fluorescent bulbs dim gradually over many months. It’s contextual as well - if I just gave them a big dose of fert, and I still need sunglasses to look at the bulbs comfortably, the plants aren’t green for lack of light!
As far as stuck seedlings it’s going to be one of four things, or a combination (each of these 4 probably needs its own post):
1) overcrowding - this is probably the most common reason
2) underfertilization - prob the number two most likely scenario, especially if the seedlings are well spaced out in the pots
3) over-fertilization - when nonfatal this causes the plants to cease growth or produce very odd, slow growth that looks like it came from a bog near Chernobyl. (Side note related to point 3: a TDS meter is an absolutely required gadget. Also, you need to test your soil pore water, not just tray water, since evaporative concentration will be intense in a grow chamber and you need to know what's going on at the root zone.)
4) grossly inadequate lighting - I’m talking seriously dim here - properly spaced, fertilized seedlings will still grow very fast under moderate intensity light, though they will look green and a bit leggy, so this is probably the least likely reason.
So long story short I have had far more bottlenecks related to nutrients and spacing than light quantity / quality. It’s tempting to focus on light because it’s easy to measure quantitatively, whereas knowing the sweet spot in a multifactoral system is more subjective and requires trial-and-error over time. The pics below show what I like to see in my seedlings under lights: vibrant colors and steady growth from one leaf to the next. These seedlings are under somewhat old, cheap, off-brand, totally not optimized T5 bulbs but are spaced properly and receiving a moderate Maxsea dose through the tray water (pics taken today - this is how I get through the Oregon winter with minimal plant withdrawal!)
Untitled by Calen Hall, on Flickr
Untitled by Calen Hall, on Flickr
Untitled by Calen Hall, on Flickr
As a practical matter, I judge light quality and quantity by how the plants look. Seedlings should display the same color tones and intensity as optimally grown mature plants, essentially. If the seedlings are looking bright and vibrant, that tells me all I need to know without necessarily involving various gadgets / the Large Hadron Collider, etc. When your seedlings are looking like pictures taken in meizzwang ‘s yard, you’re doing it right!
Certain circumstances can complicate this. For example, aggressive fertilization will cause the plants to green-up, mimicking under-lit conditions. When I see my seedlings green-up I know they are at the upper end of what they can tolerate nutrient-wise. It’s usually pretty easy to distinguish this from bad lighting because it has a sudden onset (1-2 weeks) whereas my fluorescent bulbs dim gradually over many months. It’s contextual as well - if I just gave them a big dose of fert, and I still need sunglasses to look at the bulbs comfortably, the plants aren’t green for lack of light!
As far as stuck seedlings it’s going to be one of four things, or a combination (each of these 4 probably needs its own post):
1) overcrowding - this is probably the most common reason
2) underfertilization - prob the number two most likely scenario, especially if the seedlings are well spaced out in the pots
3) over-fertilization - when nonfatal this causes the plants to cease growth or produce very odd, slow growth that looks like it came from a bog near Chernobyl. (Side note related to point 3: a TDS meter is an absolutely required gadget. Also, you need to test your soil pore water, not just tray water, since evaporative concentration will be intense in a grow chamber and you need to know what's going on at the root zone.)
4) grossly inadequate lighting - I’m talking seriously dim here - properly spaced, fertilized seedlings will still grow very fast under moderate intensity light, though they will look green and a bit leggy, so this is probably the least likely reason.
So long story short I have had far more bottlenecks related to nutrients and spacing than light quantity / quality. It’s tempting to focus on light because it’s easy to measure quantitatively, whereas knowing the sweet spot in a multifactoral system is more subjective and requires trial-and-error over time. The pics below show what I like to see in my seedlings under lights: vibrant colors and steady growth from one leaf to the next. These seedlings are under somewhat old, cheap, off-brand, totally not optimized T5 bulbs but are spaced properly and receiving a moderate Maxsea dose through the tray water (pics taken today - this is how I get through the Oregon winter with minimal plant withdrawal!)
Untitled by Calen Hall, on Flickr
Untitled by Calen Hall, on Flickr
Untitled by Calen Hall, on Flickr