Fruit: what ripens after picking, what does not, what must not sit together

Apples and bananas ripen everything around them — trick and problem at once. Eat berries at once, citrus in the fridge.

Ripen after picking (ethylene producers): apples, bananas, pears, plums, tomatoes, avocados, kiwis. Ripen at room temperature, then store cool.
Do not ripen after picking: berries, cherries, grapes, citrus, pineapple. Buy ripe, store cool, eat soon.
An unripe avocado next to an apple in a paper bag — ripe overnight.
Never put apples in the fridge next to potatoes, cabbage or lettuce without a bag — they make everything wilt and sprout.
Do not wash berries until you eat them — water makes them mould in hours. A tea towel in the bowl absorbs moisture.