Use a weight to keep fruit submerged in the rum. Put a lid on the jar and store in a cool dark place.
Keep adding fruit (with ½ it's weight in sugar) to the jar and top with rum.
When the growing season is done (or your jar is full) let age for another month or so to fully develop the flavors.
Notes
An overproof rum is more traditional and will help keep the fruit from fermenting.Start this at the beginning of the produce season. As each fruit comes in season add it (along with ½ it's weight in sugar) to the jar and cover with rum. After the last addition of fruit and sugar, you want to age it for a couple of months to fully let the flavors develop.Best fruits: strawberries, peaches, apricots, pears, grapes, pineapple, raspberries, blackberries, blueberries, plums and figs. Blueberries and blackberries may color everything purple. Fruits to avoid: melons, apples, bananas, oranges, grapefruits, and rhubarb.