Light ,heat burn ?

High, Nute burn and because of that I know that your deficiency is due overfeeding and that this caused nutrient lockout. You need to flush the soil and after flushing give 75% of the nutrients that you age till today. You can do this flushing by slowly pour water pH 6.2 onto the top of the soil, allowing it to drain freely from the bottom of the pot. Pour slowly, so the water doesn't overflow from the top of the pot. Use approximately four times the pot's volume in water to flush the soil. For example, use 1 gallon of water for a 1 quart pot. After the flushing you need to let the soil (almost) dry out completely. Then start to give water again like you did till now but with less nutrients. At this stage you can start at EC 1.5 and build this up every week till they reached EC 1.8 (do not give more then EC 1.8). This is the maximum to make sure that you don't overfeed them and cause more nutrient lockouts. Happy Growing! 😋

I'm with m0use on this one... heed his advice about feeding when it's hot - and be careful not to splash water or spray with anything when it's in the sun. If you're spraying for bugs, always do it at dusk. Good luck!