Congrats on your first grow! Been smoking weed most if my life at this point but growing truly completes the circlr for me... Unless it looks extreme I wouldn't worry too much, as the plants been alive for a few months some of the oldest lower leaves will fade and fall off. I just see it as they're not really needed anymore, not getting any sun and the plant is just focusing growth in other areas. Did you amend your soil with fertilizers at all when you planted? If your soil is balanced and nutrient rich to begin with she may be good, if you think it needs some help you can top dress with organic fertilizer, compost, worm castings ect.
When I was talking about adding teas or recharge to help the microbiology was really more along the lines of helping the soil food web break down the nutrients already there to make them more available for your plant. If you have rich native soil full of worms your soil is probably pretty damn good but when you are mixing soils for container or raised beds and you add your dry amendments in there for nutrient values, you need to make sure there is enough microbial life in your soil- beneficial bacteria, fungus, humics, that break down the bone and feather meals and granular fertilizer we add to the soil. Basically with organics there needs to be life in your soil to break down the food for the plants, yeas or recharge do just that and add life into or back into your soil. Worm Castings and compost have microbial life and can do wonders when top dressed.
If it's just been getting water from the sprinklers so far if may be time to start hand watering now assuming it's pretty big. Id top dress with some worm castings and water that in by hand. Your only going to help, then you can reassess in a few days if your plants need any more nutrients after your sure there watered good and the soil life is helping along.