Am I this year? No. Have I? Yes. They're on the "easy" but "slightly time-consuming" list. :-)

Varieties: I'd actually choose at least two--one short-day and one long-day to get a longer period of blooms. Sweet pea tend not to bloom well into summer as they don't like the heat very much, but you can also adjust that a little by growing them in part-shade conditions with morning sun up until about noon and protecting them from hotter afternoon sunlight. It also depends on your locale; in PA, August just isn't sweet pea weather most years.

Even so, you have many to choose from, from dozens of suppliers, in dozens of colors...

Indoors, before frost:

Plant 4 to 8 weeks before frost to give time for the plant to grow in before transplanting outdoors. They'll blossom about 8-16 weeks (cultivar depending, taller ones usually take longer) from planting date.

I'd start them in 4" pots as they don't transplant easily or well from cells, grow fast, and develop deep roots quickly. They'll potbound fast, so 1 pot to a customer.

Most sites recommend soaking seeds 24 hours before planting, or nicking the seed coat with sandpaper or a nail clipper, and that's fine. I never did, they just took a little longer to sprout.

The seeds generally sprout in 10-14 days at room temperature. Extra heat is not required; sweet pea are cooler-season plants.

Once sprouted, light, light, light. These are full sun to part shade plants, so the brightest light possible. Windowsill light probably won't be sufficient in early spring, so you'll most likely need to enhance it artificially.

Sweet pea can tolerate a frost, but cannot stand temperatures under 25. I don't transplant until temperatures are unlikely to go under 32--for me, about April 30th, still before my last frost date. If you get surprised, water the plants and make sure they go into the night wet. Water takes a while to freeze and remains at 32 degrees until it fully turns to ice.

Outdoors, later on:

Soak seed for 24 hours before planting (this will save time, accelerate sprout, and give some margin against going dry outdoors).

Plant outdoors where you want the plant when the soil can be worked (it's still quite cold, that's OK, the seeds are very durable). Leave at least 4-6" between seeds.

They'll sprout when they can. Keep the soil damp, but not soaked.

Growing on:

Sweet pea will require a trellis (well, most of them, although I've seen some left to ground crawl that looked really nice, or left to eat various garden boulders). Some dwarf varieties only grow to 10" as well and won't need one (and have differing start periods from the above).

Thanks so much for all of the great information!