Where is Koma no saito

Can someone please tell me where the "Koma no saito" (spider lilies field, maybe it should be spelt "sato") bloom each summer somewhere in Saitama. I saw on tv that over a million of these lilies bloom in one place which is visited by lots of tourists and I would love to include this in our 2011 August trip to Saitama, Nagano and Gunma as my wife loves flowers. We plan on driving from Tokyo so some directions from either the Chuo or Kanetsu expressways would help me a lot. Thanks.

It seems you're looking for Hidaka City. This page is in Japanese only, but you may be able to get enough info from an online translation through Google or a similar site.
http://www.kinchakuda.com/

Thanks so much Laenir for your reply. I found Hidaka shi on the map, it is quite close to Tokyo. As the website is in Japanese, can you tell me when the spider lilies bloom, is it August or September ?