Seedling stretch?

These don't look stretchy. A good visible sign is the color of the stem. If it remains white-ish, it's probably a bit too stretched out. Even if that happens, more light will fix it. When you transplant, you can bury an extra inch or more of stem if you want to. it will eventually lose color (chlorophyl isn't needed where there is no light) and sprout roots like any other buried portion does. You don't want to bury too much too often as that does increase some risk for infection before it can differentiate into root cells... just as you don't want your above ground stem to be wet 24/7 for same reasoning I used to be real keen about keeping seedlings shorter... it was fine until one got stunted... that's a far worse condition than a little minor stretch. I'd rather prop a couple seedlings up for a week or two and let them show me they need more light as i ramp up to full power. Unless it's going to be a very tiny finished plant, those early nodes aren't so important to keep tight beyond common sesne... the thickness of vascular tissue is still relevant, for example. I keep them reasonably close, but those early nodes will never had buds in many contexts. So stem color will help you adjust intensity of light as well as internode length -- the distance between growth nodes -- after the 2nd or 3rd node, the cotys and first serrated blades are always on top of each other for a day or three. If they stay super tight after that, you are giving too much light at moment. If they stretch too much, you need more light. You don't want 3-4 sets of leaves (6-8 leaves) all sprouting from some small length of stem on a tiny plant. Not only that there's potential the plant just stalls-out if given too much light and nodes stack up. It'll just stop growing for a period of time. It will stop trying to reach higher because it's unhealthy for it to do so in some contexts of intense light... genetics will add variance too. Reducing light is the obvioous answer, but the growth doesn't necessarily restart overnight... may take a bit of time for vigorous growth to restart. It's easy to do... my Northern SPice were a bit too tight, initially. i reduced to 75%... 24 hours later it helped a little but not enough... i reduced to 65% and raised light 2" (cause i ddin't want to dim much lower... efficacy changes and the SFD of emitted by diodes are not guaranteed to remain consistent with extreme dimming, so height from canopy is just as good at reducing intensity in any one spot - inverse square law). Now after another 24 hours i like what i am seeing. it just takes a little effort to find what they are happy with at times. Always best to make small incremental changes and observe how the plant reacts, unless something extreme is happening, then you can kick your reaction up a notch. The pictures in that diary won't show the improvements over the last 2 days... might show the results of first adjustment i made in recent update... but the 66% was done yesterday (wed) and update was tuesday afternoon. take a note of what works at each stage of life for the light you are using (seedling, immature vege, mature vege.. bloom - if photo's bloom is really proportionally the same, but if you go 18h to 12h/day it needs 150% more light per hour... it is proportional to late vege.. with autos, it's the same "max" as long as hours of light don't change).. it will not be exactly the same each time, but it'll be very close and much easier to make smaller adjustments. The plant will tell you through the internode lengths and potentially leaf issues what amount of light it wants. less obvious symptom -- for multiple hours at end of day it droops like crazy. Likely giving a bit too much light per day... it may not happent he first day, but could build up before it's notieably drooping for long periods of time. Raise light or dim... usually better to raise a light in bloom phase as that spreads the light rather than reducing the total radiated... will help on edges and underneath with more reflecting off walls. in vege phase i'll save watts and use dimmer option up to a point. some drivers are better at lower percentages than others. regardless the diod spec sheets don't guarantee consistency below given amperage/watts/volts. (not an electrician, lol, one of those things.. amps? concept is real, though)