I usually like to plant my lettuce plants mixed among other things, but in this patch I've planted it all together.
These are planted really close together, and they get really thick very quickly and block out about 90% of weeds, and I leave the other 10% that is left usually, to form a natural
polyculture, and any big or aggressive weeds can be clipped out easily if needed and the large numbers of lettuce plants will quickly shade it out.
The toughest and best plants will survive to be turned into salad most likely!