How to increase tricomes

is there a way to get more tricomes on my plants befor i chop them down so i would get hier?would bloom boosters help?nutrents?

there is this product called purple maxx that is supposed to help make more oils and make the plant purple but im not sure if it really works ,i used it on my first grow and my plants were really good and now that think about it i didnt use it on my second grow that didnt turn out as high grade and i did everything the same except not using purple maxx so maybe it does increase thc