They could be hot for either 2 reasons: 1. THey were left in the ground
for too long, or 2. They did not have enough water.
Myrl Jeffcoat wrote:
All-
I remember there is a little trick to what makes radishes hot, or not
so hot. But, I can't remember what it is. Is it something about when
you pick them?

I pulled some up this morning, and they are blistering hot.

Myrl Jeffcoat
http://www.myrljeffcoat.com