Alfalfa seed sowing

My alfalfa seeds have arrived ready to go in my front garden as green manure.

The pack says I have to sow onto dry soil, and that it needs dry soil.

This being the case, how will they germinate?

Surely it doesn't mean literally bone dry?

It also says it may need protection from slugs, which seems contradictory, seeing as slugs are most active when it's wet.

 

I have used this in the past and I just sowed the seed as any other green manure. The information I had was sow Apr to July broadcast seed fairly thick rake to cover and water if dry. I have never had to water. Perhaps slug protection is for if you want to use as a forage crop.
Because of the dry weather this year I've yet to sow any green manure, when we get some rain then I will be sowing grazing rye, vetches and if it rains before mid October phaecelia to overwinter.