I have some seedlings. They are a week old. They looked great yesterday. I gave them water with nutrients the first time. It was oh at 6.0 and Pom was 500 or so. Today I wake up to this brown creeping up the leaves. What caused this? How do I fix it? How do I prevent it from happening again?
Welcome to the community. Seedlings do not need any nutes for the first few weeks. They only need a tiny bit of moisture. You can cause root rot. Donât water anymore until it dries out. That is MHO. I will ask others more experienced than myself.
@oldmarine @PurpNGold74 @Pet_de_Chien
Looks like they got nute burn. Whatâs the soil, most peat mixes have enough for 3-6months, also drainage holes in that cup.
And yes as stated sh!t goes sideways fast when they are little. most kill em with too much love, than neglect.
It seems that @Flitme has you covered with some good advice. I canât see if you have drainage holes in the solo cup or not. If not, you must make some drainage holes.
I donât usually add nutrients until my plants are about a month old or more. When they are well established in vegetative growth is when they may need their first feeding. As suggested by @Pet_de_Chien , it does depend upon what soil you plant them in. I put seeds in very plain starter soil until the first transplant into Fox Farms Ocean Forest when they are about a month old.
Well here is something odd I just noticed. All 3 of these plants I have done everything identical to. 2 of them have this issue the 3rd is still doing amazing. The only difference I found between the 3 is in the diy humidity domes I made. I noticed the 2 that have the problem the dome was not connecting with the rubber mat underneath. The one thatâs doing great was connecting. It had a lot of condensation on the plant as the other 2 were dry. I taped the bottom of the 2 domes tk the mat. Hopefully that helps. I have found humidity is my biggest problem. Trying to keep it at 40% is a pain I. The ass let alone trying to get it to 65% even with my grow tent and 2 humidifiers.
Really a month in? Everything I have read says give the first nuts after a week or two. I usually give them a dose of 400 - 500 ppm of sensi grow a and b about 7 - 10 days after. So this is not a good practice?
The soil is fox farms with perlite added. I also add rocks or clay pebbles through out to ensure good drainage. I also do have holes in the bottom.
So what should I do? Should I flush ?
Lol I mis read your last comment. Thatâs a very good analogy there. Kill them with too much love seems to be about right when it comes to these guys. Neglect may be the word of the day 
If this works for you then you should stick with that. I just shared with you what has been very successful and effective for me.
No itâs clearly not working for me lol. I was just stating what I have read. I want to find the correct way. If your way is the correct way I will gladly follow your advise. I just want to clarify is all.
And it seems the 3rd does have it as well it was just hiding under a curled leaf
I want to be successful and effective too damn it. 
I donât think that there is a âcorrectâ way but as @Pet_de_Chien points out, many folks do too much to their seedlings and end up killing them or stunting their growth.
Too much water and nutrients too early are a couple of the best ways to kill seedlings. They donât need much water or nutrition until they get established. Most folks would advise against putting seedlings into Fox Farms soil because it is too nutrient rich (or too hot) for them. That is why I use really plain starter soil for the seedlings. It has almost no nutrients, just enough for the plant to establish a nice root system before hitting them with the hot stuff.
Learning to grow cannabis takes some effort because it is often counter intuitive for folks that have grown other house plants or vegetables in the garden. The folks in this forum taught me everything that I know about growing.
The key is to learn from your mistakes and successes. Many folks struggle with their first few grows. My first grow was several years ago and I nearly killed the first seedlings due to over watering and low temperatures. My friends here walked me through the process of getting on track and my first grow was a reasonable first effort at about 3 ounces per plant. Now I get about 1 lb per plant after learning a bunch of stuff and fine tuning my grow areas.
The good thing is! If you slow down, I doubt you are going to kill them from whatever this might be.
Let them Dry out and water only when the cup is light/dry, until you see if you can reverse direction. You can feed them all day, but they do not have a root established that can uptake much yet and will burn. Keep in mind, damage done will remain: the burn and claw will stay. But to know if you on the right path watch the new growth. Lose the humidity domes at this point you could still dampoff and thatâll just rot the stem at the soil line.
PH for soil grows should be little higher 6.5, but 6 isnt gonna cause what youre seeing.
Which Fox Farms soil? Ocean first for example has enough food to carry an auto to flower, usually up to 6 without nutrients depending in your watering habits.
I donât feed my seedlings the first few weeks. When I plant seedlings and rooted clones I use very weak soil (4 parts coco and 1 part compost) and they are good for about a month. They donât get their first true feeding for about a month.
Fox farm definitely doesnât need nutes for the first few weeks. Fox Farm Ocean Forest cntan run your plants by itself up to a solid 5 weeks. Iâm no pro, but I would guess that adding nutes, while still under the domes, would actually put nutes in the humidity and burn your plant from the outside. Kinda like splashing the lower leaves on bigger plants when feeding them. Just my thoughts. Except the FF soil, it really has lots of nutes lol. Other great growers have already chimed in tho and will help steer you where you need to be. Good luck and happy growing!!!
This is why. FF soils are pretty âhotâ from the start. If not in coco, feeding from this soon gets u nute burn.
Also dont wet leaves during lights on. The water droplets can âlenseâ and burn leaves.
My bad for repeating info. Just caught up. These good folks defo got u faded tho. Happy growing.
Straight out of the bag FF coco loco is 850 PPMs, FFOF is hotter. Happy frog a little less than coco loco. As all have said these mediums will carry the plant for 4-6 weeks with PH water only
Dude, you got a lot of help from a lot of experienced and knowledgeable people.
My suggestion is that you read this. At least twice. I have read this multiple times and refer to it often.
Best of luck and happy growing.
Somethings are worth repeating.
