Mine get the following once a month: compost, composted manure, milogranite (lots), and some cheap 10-10-10

I also spray the foliage weekly with water-soluble granules like Miracle Grow or Peters.

ok, I will try that!

When I bought it last year around September, the height was around 42". It was really funny because the height before I planted was at 1 foot tall. LOL. I think, the reason for this is that it wasn't getting enough sunlight inside the house.

Can we dig them in fall and just let the corm exposed in our basement? Then in spring, we can plant them again. This way, their height will still be the same.

Thanks!

Yes. You can lift the entire plant out of the ground and store it in a cool basement (mine is approx. 50 degrees F) in total darkness. I also cut off all the leaves except the last one that is about to unfurl. I usually can overwinter them for the first winter only. After the second growing season, they are way too big to transport!

What if they dry out, will they die? Should I cover the corm in a plastic bag so it won't dry out quickly?

It is definitely better to under water than over water when the plant is not growing.

I usually put mine in a pot and water very lightly once or twice throughout the winter. The soil is completely dry for most of the winter.

That means, it's possible that the last leaf we left can turn yellow or dry out during the whole winter. Am I correct?

The plant will not go completely dormant as soon as you bring it inside to the basement. The plant will continue to grow very slowly throughout the winter. I usually get two unfurled leaves by spring. These leaves are often lighter green due to lack of light. The objective is to slow down the growth as much as possible by lowering temperatures and withholding light and water.

What do you do with it when it is too big to bring in? do you cut it down to the soil and cover it with mulch or something?

I let mine die. Come spring, my dead plants are replaced by other one year old plants.

I suppose you could cut back the second year plant enough to bring it inside. My second year plants are bigger than my house!