@BEgrower,
Worm casting is a great option always. Also, malted barley is fantastic, but should be used with other ingredients.
https://www.leafly.com/news/growing/top-dressing-soil-for-growing-cannabis
https://www.royalqueenseeds.com/blog-top-dress-your-weed-plants-to-feed-your-soil-n1265
https://www.royalqueenseeds.com/blog-the-home-grower-s-guide-to-the-best-soil-for-cannabis-n810
@BEgrower, to create a micro climate so the root don't dry on top like it's now.
If you cover with anything the new climate will make roots develop and raise until the top. If it's organic would be even better, to slowly release nutrients and develop microorganism.
It's just win!!!
When you cover you make the root ball of the plant even greater, meaning more plant matter, more flower, better final product.
Also, perlite would be great too!
