Planting in small greenhouses and packed cold frames begins at the end of February to mid-March, depending on the weather.
For lettuce plants stand distances of at least 20 cm x 20 inches required, it's better though, auf 25cm x 20cm oder 25cm x 25 cm to go. This results in qualitatively better and larger heads, and the risk of rotting is less than if it is too dense.
The foil tents can also be planted from around mid-March, whereby the same stand distances are to be selected.