How soon do I dare plant Sweet Pea seeds directly into the ground in South Jordan?
As soon as you can work the soil. Peas need the soil to be over 40 degrees in order to emerge. Mine are already coming up. Peas are one of the hardiest vegetables out there and can withstand snow and occasional frosts.
I would consider "chitting" the seeds before planting for a better start. I have posted on this in my blog
I would get them into the ground as soon as you can since they don't like temperatures over 80 degrees.
Here is a link that might be useful: My blog
These are Sweetpea FLOWER seeds. Can they go in as early as vegetable peas?
That I would not know about. I only know vegetables and leave the flowers up to my wife. I would advise reading the seed packet and it should tell you.