I’ve sown Giant Stuttgart onions. Some in polytunnel in April and the rest outdoors in June.I sprinkled some organic fertiliser twice during year and watered them regularly.However , they never got passed the scallion size (i.e. 1 inch diam. ).Should I leave in the ground over the winter or eat them?
Presuming these Stuttgarter Giant onions were grown from sets, April should have been okay but sets should be planted outdoors early in that month and June is too late for this variety of onion, either sets or seeds.
Late-planted autumn onion sets or Japanese onion seeds can be sown in July or August.
The soil may have been too low in nutrients, too dry(indoors) or shaded as growth is obviously affected.
Use these as they will go to seed next year.