It could be a few thing: how much do you water? What do you feed? How much sunlight do they receive? H. coronarium can actually grow in standing water , it diesn't have to be THAT wet but if it's full sun it should be damp to keep it looking nice. In too much shade it won't bloom enough and the pseudostems aren't as sturdy. I find most heydichiums that we grow are grown in morning sun with a break from about 1pm to 4pm. I am in central florida and the afternoon sun is very intense. I feed with nutricoat (it's called Dynamite on the retail market) 13-13-13 w/mimors. i also give them some milorginite and conpost and mulch with oak leaves which put a little something back to the soil. I hope this helps.
Liz
If you'd like to see some pictures of my gingers just email me at leneobrien@aol.com and I'll send you my AOL photo album.