How to have success with spinach?

I had lovely spinach this year - planted it (Picasso) in March/April under netting and in shade, and it grew a treat and was lovely until it bolted last week. I think the mistake I made was just planting too much. I think it will always bolt if we have a hot spell, so it's one of those things to grow sparingly and just enjoy while it lasts. I did freeze some, but to be honest once I'd blanched it I was left with such a tiny amount it really wasn't worth the effort.