What is wrong with my plant?

I'm replying as a novice, but precisely for that reason, I do a lot of research. Burnt tips in cannabis are usually a sign of plant overfeeding. I see they're in flowering, about 3/4 through? How much PK (phosphorus/potassium) are you giving per liter? If you're overdoing it, plants lock out nutrients and 'stop growing,' besides showing burnt tips. In this case, a solution would be to stop fertilizers and flush the plants with plain water (pH-adjusted) and monitor results. From the leaf color, they also seem quite rich in nitrogen. However, I don't see the 'yellow' lower leaves you mentioned – could you add photos to be more precise? Yellowing leaves starting from the bottom could mean several things. The first that comes to mind (and I've experienced myself) is magnesium deficiency, but again, without photos it's very hard to determine the cause. I'll share some useful links that personally helped me. Don't panic – there are tons of info sites and grower forums, and everything can be fixed! Peace. https://www.royalqueenseeds.com/us/blog-nutrient-burn-in-cannabis-plants-n680 https://www.zamnesia.com/uk/grow-weed/497-magnesium-deficiency

3 options here - N excess and P,K lockout (stop using N fert) - NPK deficiency (up ppm or feed more often) - could be a bit of both

No diary so no idea what your feeding, looks like plain old high ec in medium with a dash too much nitrogen. Nitrogen comes in a couple forms, NH4+, NO3- and NO2- Helps to know what kinda your adding. More than likely it's negatively charged anions which acidify soil, so if nitrate/nitrites NO2-and NO3-is in excess I'd imagine the soil is lacking the cations to balance things out. I'd guess your ph is lower side of 6. But that is just a guess. Amd i know nothing Jon snow. Hope she works out.

tip burn is not always toxicity... you can look at any leaf symptom chart to see this is true. you can be overfeeding one thing and underfeeding something else, so both a def and tox present is not impossible. could also be one thing is high and lockout out something else (see Mulder's chart for most likely relationships). There's no provided info to give specifics. You may or may not be overfeeding. Leaves look a bit lush and didn't progress much beyond 5-finger leaves? So, yeah, probably overfed soemthing. More than one thing causes dark foliage than just high N. If paling tip-in from bottom-up that is a sign of N-deficiency, assuming soemthing isn't impeding it. so i'd look to too much Ca or Mg, which can cause dark foliage. check a leaf symptom chart for all the possibilities, then you have to use other info to eliminate options. if in soilless, this is incredibly easy to compare to known formulas that work with 95-99% of seeds planted. trial and error till you get there... leaf symptoms are not discrete. You always need somethign else to help eliminate possibilities. trackign what you do over time helps greatly. being familiar with the products you use helps greatly. Soil brings a ton of unknowns, but you can get familiar with a specific product over time. google image search -- muldur's chart and 'marijuana leaf symptom chart' ... necessary tools to have available. you can learn it as well as anyone else. a good chart explains immobile vs mobile and has a high resolution for you to zoom in.

Yes, to both growmie, your overfeeding and your beginning to see the early signs of a deficiency, to sum it up for you.

Yes, you have been feeding way too much...........the last thing you want to do is give more nitrogen and cause even more burning! The bottom leaves going yellow in this case is due to them being in shade and not photosynthesising effectively, so the plant basically "gives up" on them. Reduce your feeding, either the amount or the frequency and do not flush, this can release even more nutrient salts from the substrate and accelerate the burning........just slow down with the fertilizers. Now that it is flowering, all branch growth more or less stops and the plant switches its attention to flower development. Some plants grow flowers steadily, others grow flowers in spurts and others seem to start, stagnate for a while then go crazy in the last couple of weeks. You don't really have too much to worry about, but yes, you have been over feeding, so ease up on the fertilizers and everything should turn out ok.

hello gromie so the upper leaves are nute burn and the bottom stuff is going to be a nitrogen deficiency you need to flush her and next time you feed her give her some more nitrogen based nutes. Also try to add some microbial support if you have some gromie.