We do put wheelbarrow loads (25 this year) of good compost on the gardens every summer so I suppose that is fertilizing....

But...

I spent an entire year, years ago, faithfully fertilizing my house plants, on schedule, and didn't notice a difference from previous years when I never fertilized. Now I don't bother.
They do get watered with rain water in the summer and aquarium water in the winter...might be some nutrients there.

I also water with aquarium water, and notice a difference from when I used nothing.

I always thought it was such a waste when Hubby had to drain 1/3 of the aquarium every couple of months. I had him drain it into his old wine carboys (sp?) and used it for my houseplants, until the cats started knocking them off their chairs trying to get a drink. (what a mess!!) Now, I just dip my watering can right into the aquarium and Hubby tops it up when it starts to get low.

Yes, that's how I do it. Once a week I do about a 1/3 change where I just take from the top with the watering can and water everything. Then, once a month or so I do the big vacuum out and that fills up several 5 gallon buckets. I take that water everywhere inside and outside. No use in wasting!