If you were using a foliar (through the leaves) feed, and it was rinsed off, the downpour has probably helped it to reach the roots - which is just where you need it.

Probably (IMO) the 'best' fertiliser to use is good aged compost used as a mulch or mixed through the soil each time you dig up your perennials to divide and replant them.

A brew with more potash in it will help plants as they flower and set fruit/seeds. If you grow roses - an application of a mix with higher potash will help the stems harden up to face the winter.

If you are growing something for foliage - higher nitrogen can help BUT it can make the plant a luscious destination for slugs 'n' snails:-(((.

Liquid manures such as seaweed, worm casts, fish emulsion, can also be useful, particularly if you tend toward organic growing. And some pests cannot abide the taste of the fish emulsion - which is a plus!

Big caution - you can over-feed and it will show as burnt-looking leaves. Depending on your soil/location you might get a build-up of salts. It is good gardening to build up the soil with the compost as well as providing supplemental feeding.

But you can't over feed with compost!
I am all about alfalfa pellets...I see amazing growth....and there is no danger of burning.
Bagged composted manure is also good....and if you have a source and a place to age it...about any vegitation eating animal's manure...goat, sheep, cow, horse....elephant!!
Linda C

Oh oh. If the plants you are fertilizing are perennials they will not benefit much from a fertilizer watering. Why? If they are established plants their roots will already be a long way down. You need to work fertilizer into the soil and that means....a fork. First you need to decide what your plants need best. Do they need more leafy growth, more fruit or flowers? If the former you need a nitrogen rich fertilizer. I use pig dung - that's cause I'm near a pig farm but horse or even cattle dung is just as good. If your plants are stout and healthy but just need to produce more fruit/ flowers I recommend....wood ash. It is high in potassium and phosphorus and costs nothing. You can just sprinkle it on the top as it works quickly into the soil without any assistance, if you have good rainfall.