Longwoods Tropicals

First of all I would reduce the frequency of fertilizing to once per month or even stop it if the plant isn't actively growing. Only increase the dose when the plant is vigorously growing. Also let the plant dry out, at least the top inch or two of the soil. In the winter indoors don't expect much from the plant unless you give it lots of light (t5 HO fluorescent bulbs work great) along with warm temps.

What I'm trying to say is don't expect fertilizer to magically transform the plant without the environmental conditions necessary for healthy growth present.

I hope that helps, good luck and welcome to bananas.org.