In our July OOGA meeting, Professor Haldor Howard included in his presentation AAS plant trials by his students. Here’s the list of the cultivars his class started from seed in the greenhouse and then transplanted outdoors:
Avalanche white beet
Red Kingdom mizuna
Snak Hero snap pea
Bopak pak choi
Where to buy: https://all-americaselections.org/buy-winners/
All their cool season veggies were All-America Selections award winners . The class planted them outdoors at close spacing and used row covers on low hoops. See photo for example of how you too could utilize hoops and covers.