My local nursery had six-packs of sweet peas out for sale this weekend - is it really not too late to plant these? Maybe in a spot with afternoon shade as protection against the summer heat? We're in Sunset zone 16.
Well, my show for this season is almost over, at least for annual sweet peas. Shortened flower stems, foliage turning tan. Mid-May to mid-June is the time for best bouquets.
My perennial sweet peas on the other hand have just started flowering and although the flowers are attractive, there is no fragrance. I'm in the Bay Area. I sow annual seeds around Halloween time. I would save your money or spend it on a pack of seeds and get your site ready for Fall sowing.
What the heck, get them a try and see what happens. I have a sweet pea growing now in the off season just to see if it will flower...