Mine started like that and I ignored it, then this happened:
View attachment 4667796
Came here and found a few good guys that helped me out with troubleshooting what the reason behind it could be.
The things we'd looked at were:
• Water PH
• Room Temperature
• Room Humidity
• Nitrogen Toxicity
• Lights too close
• Soil too hot (Nutrient Rich)
I'd noticed the temperature for a few days had increased drastically to around 30-35°C (85-95°F), so I started leaving the tent open while the lights are on and to increase the humidity I'd put a big bowl of water in the tent.
I'd also noticed my light was producing a lot of the heat and my plant was very short and bushy, so I raised it for a few days to see how she would react and almost instantly the plant started stretching for the light within a day or two and the heat on the canopy had decreased a lot.
Another thing I wasn't testing my PH properly and didn't realize my PH levels were around 8.0 which is not good for your plants at all, so I invested in a PH meter and started by flushing my soil and correcting the soil PH with just plain PH'd water.
I was a bit skeptical on the Nitrogen Toxicity as I was only giving her plain water, but after a bit of research I'd found out that maybe my PH was locking out the plant from uptaking nutrients from the soil or maybe it could be increasing the amount of Nitrogen it's uptaking.
So my opinion if that was possibly the problem, then the previous step I took by flushing the soil should resolve it.
Now this is what I later read about and understoodand that could've potentially been the main reason behind all this and that's the soil being too nutritious. For example, Fox Farm Soil is rich in nutrients and can feed your plant for a good few weeks without any additional nutrients being added. If you add extra nutrients early on then there's a high possibility of seeing deficiencies/toxicities on your plant.
After all these slight alterations, I'd managed to get her looking like this in just under 2 weeks:
View attachment 4667819
After that I just did a bit of trimming and got rid of all the old growth that wasn't really that beneficial and that had been affected earlier with a bit more LST, she now looks like this on day 39:
View attachment 4667821