Building a Better Crop

Building a Better Crop is an Institute side quest in Fallout 4.

Detailed walkthrough
After the quest Institutionalized speak with Doctor Isaac Karlin, or after the quest Mankind - Redefined, speak with Doctor Clayton Holdren and he will mention that Karlin could use some help. Karlin will explain that they have replaced Roger Warwick of Warwick homestead with a synth and need seeds delivered to perform an experiment. He will then provide a passphrase to use when talking to Warwick.

Warwick homestead is east of Atom Cats Garage and south of the Castle. Go there and speak with Roger, giving him the passphrase. Follow Roger on the "tour" of the homestead, then speak to him again to deliver the seeds. Roger will discuss Bill Sutton's actions around the homestead, and voice his concerns that Bill knows that Roger is a synth. Roger will ask the Sole Survivor to investigate and resolve the issue for him, starting by talking to Roger's family.

Wally and Janey will not provide any information without completing a medium persuasion check, at which point they will mention Cedric Hopton going to Goodneighbor. June can be persuaded to give the same information by telling her she should be grateful or by passing a medium check.

Go to Goodneighbor and find Cedric in the Third Rail. All four speech options lead to the same second stage of the discussion. At that point, Cedric can be bribed or hit with a medium persuasion check to send the player character back to talk to Bill.

Upon returning, Roger is being held hostage by Bill. The confrontation ends one of two ways: killing Bill, or passing a moderate persuasion check to talk Bill down. Either way, the result is 250 caps reward, Warwick homestead as a settlement (if not already obtained) and instructions to return to the Institute and collect a further reward.

Bugs

 * If one already has Warwick homestead as a settlement, it is highly likely either Cedric Hopton or Bill Sutton, or both, will be killed during an attack on Warwick Homestead so this quest becomes unavailable.
 * If one has already established Warwick homestead as a settlement before this quest, issues may occur. Any settlers that are in the vicinity of the confrontation between Bill and Roger at the climax of the quest will eventually start attacking Bill. It is possible that they will already be fighting if one fast travels to the homestead during this stage. Even if one manages to quickly get through the conversation with the peaceful ending before any settler starts fighting, settlers will still attack Bill afterward at any time (even if the quest has already been completed).
 * A possible workaround for this issue (that works on any platform) is to send all generic settlers to other settlements before leaving to find Cedric in Goodneighbor. Another possible solution if playing on the PC is to simply disable any settler via the console before they have a chance to attack Bill. However, even if one specifically re-enables the same IDs afterward, any settler's appearance and inventory will be randomized and not saved from before.
 * Another possible, more complex solution (for all platforms) involves several steps:
 * Settler beds need to be away from the Warwick family beds.
 * Discovering Bill's plan before 8 pm, then waiting for the settlers to go to sleep.
 * Using a Vertibird or the Institute teleportation to get to Goodneighbour and talking with Cedric to advance the quest.
 * Returning to the homestead before 5 am, interrogating Bill, sparing him, will leave him waiting in front of the entrance.
 * Turning the quest in with Karlin results in Bill leaving the homestead and wandering the Commonwealth while remaining alive.
 * If a Minutemen radiant quest (such as Greenskins) for Warwick homestead is already active when undertaking this quest, the radiant quest may be stuck because the dialogue for this quest will take precedence and even after completion, Roger may refuse to talk about the radiant quest, leaving it stuck in the Pip-Boy for the duration of the game.
 * It is possible to fail this quest silently before it has even started. This leaves Doctor Holdren saying that Doctor Karlin needs help, while the latter simply uses one of his default lines without initiating dialogue. It is unknown what causes this, but it might be related to completing Mankind - Redefined before starting this quest. The console command allows one to start the quest manually.
 * If Bill Sutton is dead, the quest will not trigger. This can be resolved by finding Bill Sutton's corpse, clicking on it, and using the console command . After this, you will need to trigger the quest manually by using the console command.