How to thin lettuce seedlings
All, I am new to this and have planted a vegetable box garden in my yard for the first time. I am growing some romain from seeds. The seed packed said to thin to 3-4 inches. Is this enough space in between plants to grow full heads? Just want to make sure I am understanding the terminology and wanted some advice also. I have 2 rows of seeds that are 5 feet long and about 18 inches apart.