How do I care for my Eremurus

Wildflower3

I have an Eremurus Robustus that has a flower spike that has grown to over 8 feet tall and is about to finish flowering. My question is about how i care for it now so it is healthy for next year. Do I need to feed it? If so with what? Do I leave the flower spike on? the leaves are starting to brown and droop a little at the tips, I have been watering it but do I need to do anything else? So many questions! I am new to gardening and want to do the best for this magnificent beast. Thanks