Getting a second green bean harvest
Plan for a repeat crop without blocking your path.
Leave a reachable side
Bean starters grow on a trellis you cannot walk through. Plant a narrow row beside a walking lane. A solid block can leave a mature plant in the middle that you cannot reach to pick.
Count the second harvest separately
The first green bean takes ten days; subsequent harvests take three. Plant on Spring 15 and water consistently for harvests on the 25th and 28th. Plant on the 16th and only the first harvest fits. Leave the plant in place after picking.
Mechanics reference: Green Bean · Stardew Valley Wiki.