OFFICIAL WORD FROM A MASTER GARDENER! Some say morning, others say evening? So now you got me, & as a State certified Master Gardener I can not tell a lie.
Evening, late afternoon..... wrong. Never send your plants to bed wet. Or even damp. Why?
SPOTTED WILT VIRUS.
PHYTOPHTHORA ROOT ROT.
OAK ROOT FUNGUS.
GRAY MOLD ROT.
Just to name a few. When plants and soil are wet or damp when darkness sets in that's when the nasties come out to play. No parent would put their child to bed in wet clothes and no gardener should but their garden away wet either.
If you have automatic irrigation it's fine to start the program cycle just before dawn. The plants will quickly dry with the morning sun.
Fertilizing is the same thing. Plants process food with the help of sunlight. The root system is more active and can move the goodies around where they are needed. As the temperature increases so does the developmental rate of the plant.
Morning or night? Here's an easy way to remember which is best. Would you like to sit out in your garden all night dressed in wet jammies?
The Garden Dok. BS. MG. Master of Science (x2) Univ of Calif coop Extension, County of San Diego.