Rhododendrons benefit from liquid fertilization
with trace elements
granular chemical fertilizers are "salty" it is always best to water them
in. To further eliminate the chances of any burn, don't fertilize any plants that
are "bone dry" -- water them first. Be sure to keep fertilizer away from
trunks and off of wet foliage. Lightly work fertilizer into the top layer of soil if
you can do so without damaging surface roots.