Maybe I am, but I had some seeds left over from cucumbers (unsuccessful) and corn (partially successful), so I just planted them against a white wall for reflected heat.
Even though it's late September in So. Calif. Coastal, it's very hot today. (In fact, in parts of the area, in the mountains to the Northwest, the fire season is underway.)
I planted green onions, broccoli and carrots 1-2 weeks ago and they practically JUMPED out of the ground, so I figured whathehey, why not try the cukes & corn.