Some of the pictures look like bug damage but that last one looks like more might be going on. I’ll tag some people in maybe they can help.
In the mean time please add more info. Soil type, ph, nutrients, temps and humidity.
Have you looked closely for bugs, eggs, or bite marks?
Though, to me, it looks like a micronutrient deficiency or a pH issue, possibly even something else depending on what other info you have to give us (soil type, pH, ppm, temps, etc). I am no expert, so please wait for others’ advice, as well. (maybe even potassium issues?)
Your new growth isn’t affected, so that’s a good sign, for now. Certain leaf damage will never heal, even if the issue is resolved.
This does look a bit like a potassium deficiency. Are you sure there are no bugs? Have you checked the under sides of the leaves? What are you feeding?
And what are you using to check and adjust PH?
What soil are you growing in?
I am using a PH meter to check PH and I check it every time because I know it can just naturally raise over time. I am using Happy Frog soil as the grow medium, two 600 watt LED grow lights in my 4x4x6.5 grow tent. The tent stays right around 70-75 degrees F, humidity is always right around 46-50%. We are using Fox Farm nutrients, Big Bloom, Grow Big, and Tiger Bloom but we have only used the first two. We are feeding 1 tbsp of Big Bloom and 1 tbsp of Grow Big per gallon. I did not notice any bugs on the underside of the leaves or on the top of the leaves but I will look again and update if I see some.
I did not see any bug bites are bugs. I responded with more information below and more pictures.
How are you checking pH? Checking nute solutions before feeding? Doing a slurry test or runoff? Soil probe? Did you check the pH before you flushed? PPM?
Besides the leaf edges being off color, what prompted a flush? I am pro-flush when the pH is really out of whack or there are major lockout/excess issues, but if there’s a deficiency, flushing can actually make it worse. Especially if after the flush you don’t put back in the correct amount of what you removed.
I am checking PH with a PH reader. I check PH before I use it every time and if I am using nutrients I check it AFTER I add in the nutrients. I did not check the PH of the runoff. I did a flush because the edges of the leaves were starting to look burnt kind of and everything I read/saw said it looked like nutrient burn.
I did wait before putting nutrients back in. Hopefully that is my current problem and I just need to not make that mistake again down the road. I read somewhere to wait a week after a flush to let the plant use up the remaining nutes before adding more but that was obviously not the right move since a few days after this flush all this happened. For future refrence as long as I stay on top of nutes from here out this current problem shouldnt happen on future leafs and if it does it is something else? I alternate between nute and water and always keep ph at 6.5. Should a flush happen every 4 weeks or is that a big no because the fox farm nutrient says to do this. I know now if I do to put that stuff right back. Any advice is greatly appreciated. This is our first grow and overthinking everything seems to be the problem so far.
Many excesses & deficiencies look the same, so it can be hard to diagnose.
Your nute schedule, your watering practices, your pH, & your grow medium can all work together beautifully, or they can be diametrically opposed. They all affect each other, though. If you check your runoff’s pH & tds (total dissolved solids), you’ll get a much better handle on excesses/deficiencies.
PH will tell you which nutrients your plant can access from the root zone, while your tds will tell you how much stuff (technical term), in general, is dissolved in your soil, i.e. how much food your plant is eating/ignoring. With these 2 measurements, you’ll be ready to more easily diagnose a majority of your plants’ issues.
Again, your newest growth is looking fine. If the issue pops up on your new growth, then you’ll definitely want to check every grow parameter you have going. Otherwise, we all have snafus in our grows. I promise. They’re all learning experiences.