There are many variables in addition to those two that could explain the differences and it is likely a combination of things. But of the 2 issues you list, pea transplants vs. direct seeding is a big one.

Dave

Johnny's lists Super Sugar Snap as more productive over a shorter harvest period vs classic Sugar Snap.

http://www.johnnyseeds.com/p-6211-super-sugar-snap.aspx

Maybe your peas are just fizzling out early due to hot weather and you would do better with Super Sugar Snaps.

IMHO the trick to getting a good yield from peas is to sow them very thickly. The plants don't care.

Yes, plant thick. I have a few varieties that always do well and trying a couple more this year. Sugar Ann and classic Sugar Snap do well for me.

I plant, direct seed, my first double row as soon as i can work the soil, then again the next 2-3 weekends, a week apart-ish. (wet rough weather will sometimes keep me out of the garden).

If i relied on just one of those plantings i may not see one pea. Seeds are cheap and the harvest can be buckets full. Once the weather warms, in go my pole beans right behind the peas, in, again, a three week planting, but way less thick. As they are getting a footing, the peas start to brown and crisp and pull out with ease. Planting a few varieties, (i go overboard with 15-20), will give lots of peas and beans as they have different growth times.

Early on i had given up on peas for a few years thinking i had the wrong climate but now that i 'insurance' plant i get enough to give plenty away.

I get all my peas from Johnny's. And a random pack here and there if i can't help myself from the nursery racks...those racks seem to have a 'buy me' magnet. I try not to look...