After hiding from Voldemort for some several months James and Lily (and Sirius) found it harder and harder to go about daily tasks that should be a lot easier than they actually are, like going shopping. Much to Sirius' regret James, Lily and Harry had to become self-sufficient to an extent. This was mostly because Lily decided that James wasn't allowed to use his cloak any more because going out at four in the morning to go to the beach with Sirius in the south of England is "completely irresponsible and dangerous". The beach, as it may be, is a lot more enjoyable than being stuck in Godric's Hollow waiting for your death.
Being self-sufficient entitled that they would have to grow their own food.
"WHAT?" Sirius demanded as soon as he found out of the monstrosity. He looked out from the small kitchen to the vegetable patch with a face full of hatred and horror.
"We're just growing some vegetables, Padfoot." Lily sighed. "Or would you want to have to go to the shops again to buy food for three people every week?"
Sirius grumbled something under his breath. "Well, I don't want you to become fucking hippies either."
"Don't swear in front of Harry!" James warned from the sitting room.
"We're not hippies."
"You're going to corrupt Harry into becoming a weird pot smoking, organic loving, cotton wearing, sandal donning vegetarian!" Sirius cried. "You're going to destroy him!"
And with that Sirius picked up baby three month old Harry and took him to the back garden to teach him the proper way to deal with flora.
"Now, this is a tomato plant. It is pronounced tow-mate-oh. If you pronounce it any differently you're getting cut from my fucking will." Sirius explained as he picked a not very ripe tomato and threw it to James.
"Language!" Lily barked.
"And this, Harry James Potter, is lettuce. It's scientific name is lettuce befriends." Sirius fought back on laughter, like a sadistic bastard looking at the Queen of England falling on her face. "You make sure to remember that and to tell all your friends and teachers. 'Specially McGonagall. Say Padfoot taught you."
"Sirius, get inside this instant and give Harry back to me!" Lily said sharply, it reminded Sirius faintly of his own mother when he had told Regulus to test his magic by jumping off the third storey window.
Sirius held Harry close to his chest whispered "Don't listen to the old hag." into Harry's ear and walked back to the house with his head held low.
Lettuce befriends, geddit? My God. I make good jokes.
Let us be friends. Lettuce befriends.