Higgs Boson wrote:
That has always been my weak point. I know (barely) not to fertilize
when plants are dormant, but I always stumble when, e.g., to fertilize
my roses after mid-January pruning.

I have two young fruit trees (Plum and Apricot) which are just
shedding their leaves, and two blueberry bushes in large pots, one of
which is confused enough to be blooming and setting fruit.

I also have growing "winter" vegetable crops that, I assume, it's OK
to fertilize: Peas, beets, carrots, green onions, bok choy, stuff like
that.

Is there ONE comprehensive "when to fertilize" rule? Geared to my
mild "Mediterranean" climate -- So. Calif coastal?

TIA

HB

It's very hard to say it all in one rule that would always be applicable.

Fertilise when the plants need the minerals. That would be when the plants
have reduced (or will soon reduce) the available minerals below its
requirement AND when they need them, that is when they are (or soon will be)
growing strongly. The type, amount and frequency of application will
depends on your soil, the plants and the conditions. Over fertilising can
be as harmful, or more harmful, than under fertilising, this error is easy
to make with sources that are concentrated such as synthetics or fresh chook
manure.

David