First thing . You need to lower the temp . 74-86 is ideal 80 is a good place to sit . If you were growing in hydro temps of 90 would be less of an issue . But being in soil you really don’t want this and there is 2 reasons for this
1) photosynthesis takes place best at 74° to 86° When you drop below 74° or above 86° photosynthesis rate drops dramatically which will slow the growth of your plant
2) at 90° Unless you’re using a fairly large pot it’s gonna be hard for your plant to stay cool in the root zone your soils going to heat up and could potential allow things like root rot to flourish . Not only is it going to heat up the soil but now your plant has to put more energy into cooling itself and less energy into growing bigger
As far as watering goes you should only be watering when the soil is dry to the touch when you put your finger about an inch deep into the soil . Assuming that you’re using a pot adequate to the size of your plant when using a large pot you have to really be careful when watering because the soil will hold a lot more water then the plant can use in the period of time that would be considered safe . Allowing the top part of the soil to dry before watering Allows your roots to get oxygen.
You should keep your plant in the solo cup until the leaves grow out past the edges of the cup . Your plant at a young age will have a diameter equivalent to the diameter of the roots . So once your plants leaves are growing out past the cup I would typically transplant into a 3/4 gallon container that’s what I use for my tomatoes (I am not growing marijuana in soil) but 1 gallon is fine half gallon whatever you feel comfortable with but you really don’t want to transplant a bunch of times so going from like a solo cup to 1 gallon pot to a 3 gallon pot or a 5 gallon pot whatever your end pot is going to be would be a good transitional method . I would not advise going from a solo cup to a 5 gallon because then you risk overwatering . But you can and you just have to be careful not to overwater.
I’m just curious when you say dirt from Home Depot what kind of dirt are you talking about . Does this dirt have nutrients in it such as are you miracle grow potting mix or not . Knowing specifically what soil you’re using could potential help determine a cause . You could be using something that is greatly lacking or you could be using something that is potentially dangerous to your plants which could be causing the discoloration of the leaves whether it be a deficiency or something else .
Also dosage of feeding, run off PH ,run off ppm or ec, feeding ppm or ec, How often you’re feeding. This is all information that would be useful . If you are not tracking this information then you need to be so we can help you and you can have a successful grow . Your plant can only handle so much food at a certain size and has an ideal pH range for it To grow . If the PPM / EC is too high this will cause problems for your plant as far as intake of nutrients and water. If your pH is too high or too low this will cause problems for your plant as far as intake of nutrients and water. So this is all important information in order to properly diagnose not only the deficiency or toxicity but also the root of the problem itself . If you are unsure about how to check and track this information then that would be the first thing that would need to be addressed .
