Why the top leaves margins begans to yellow?

It was 1 month ago I don't even try to search an answer. Today she is not ready to be harvest as you asking, wait a bit more

Hey there, so burnt tips aren't always a toxicity sign, they often appear with deficiencies too. Usually relating to the trace elements like copper, zinc etc...but a potassium deficiency can also do this. I understand the desire for an inexpensive grow as things add up quickly. However since youre doing autoflower their nutrient needs can be relatively low anyway. If your soil is decent you could continue adding new soil to the top and hope those nutrients will be good, otherwise I'd hit a garden store/home depot/ or even walmart and pick up a cheap small container of a general all purpose fertilizer and use it very minimally. I saw walmart even carried a "micro" bottle a "grow" bottle etc which tells me they're probably targeting cannabis people lol. Happy growing and good luck with the hunt for the right routes. The plants are looking pretty healthy right now, so maybe just do some research and im sure a good option will pop up. ✌️

Since you are only giving water we can discard over feeding issues right away. Weird leaf issues with no apparent reason is usually pH related, you probably are using tap water, which is usually quite alkaline (to high pH) and over time it has changed the pH in your soil from slightly acidic to slightly alkaline; invest in a cheap ph pen, always measure your pH and adjust it accordingly (apple vinegar can be used as a pH down). The other reason could be over watering, which is a very normal issue even among experienced growers and your picture shows some sign of this. Let the soil become dry before watering again.

Hi @Capshot! Considering you only gave water since day 1, we can exclude nutrient burn. Your issue is not related to a nutrient noxicity for sure. That being said, we are missing some useful informations to diagnose your plants: what's your watering routine, how much water do you give each week? What's the temperature of your water? What's your medium, it's written 'soil' but what's the brand and what's the NPK ratio in your medium bag? Do you measure/adjust the pH of your waterings? Have you ever tested your tap water with an EC-meter? If you did so, what's the EC of your tap-water? These symptoms make me think of 3 potential issues: 1/ your water might be too cold, this can lead to burnt tips or yellow tips, make sure your solution is neither too cold nor too hot, 20°C/68°F is a safe temperature for roots. 2/ your probably have a bad watering routine, you must follow a wet/dry cycle, where roots are never too dry nor flooded in water, they must search for water in order to expand so whenever you want to water, try to weigh the container, make sure it's light and not full of water, give a reasonable amount of water (15~20% of your container's volume) and watch it dry, even if it takes 3 days, soil must be almost dry before you water it again. 3/ Your pH could have been wrong for the entire vegetative stage, if you did not measure & adjust the pH of your water, you could have created some nutrient-lockout. Indeed, without the appropriate pH in the root-zone, plants cannot manage nutrient intakes, and start to show deficiencies. I highly recommend to invest in a pH-pen and some pH-down, unless your tap-water has already the perfect pH for soil (~6.2, you'd be very lucky!) this is a mandatory tool for a successful run. Hope this will help, keep us up-to-date and happy growing 👊

@Capshot If you are referring to the yellowing at the tips of the leaves this is due to a Nutrient burn. The solution to this is to 'flush' your plant by watering with Pure water PHed at 6.2-6.5 for a day or two before continue back on a reduced nutrient schedule. I highly suggest cutting nutrient in half and working your way back up. IF you are referring to the yellowing of the inner leaves at the top of the plant on the new growth this is fairly normal at that level and doesn't appear to be any nutrient problems. I hope this helps 😎

good question bro, that's just the start of slight nutrient burn, even if it's just normal soil and plain water the cannabis plants needs less nutrients than other plants. To fix it just flush that means water until run off then water 20% more, and try to remove any excess water after that, the new growth should recover and it should stop spreading. Hope this helps ! 🚀