I am trying to remove years of ingrained filth and green gunk, both because I would like to not have the porch rot and fall to pieces (my back door would immediately become unusable, for one thing, since it's like... four feet above the ground? ish?) and because I want a clean surface before I spray squirrel-be-gone to protect the peppers that I will then move outdoors.

Actually, that reminds me. I should mention to Landlord Dude that the porch could use a couple new boards to replace the handful that have gone all splintery-ragged, and a coat of protective stain or something to make the still intact boards last longer. Cleaning is on me as the tenant, but structural maintenance issues are really his responsibility.