Follow the Rules of Safe Picnic Packing
Prep less than 1 day from picnic so food tastes fresh.
Transport on ice. Food should be chilled and packed in a cooler with ice or ice packs to keep them cold while they travel.
Heat just before taking. If you're bringing a baked dish, it can be cooked the day before. Reheat just before heading out; wrap the hot container in a towel, and tote carefully to the picnic.
Serve—then stow. Once folks have gone through the line and served themselves, put chilled dishes back in the cooler to keep them cold. Anyone who wants seconds can dig back into the cooler.
Use the two-hour/one-hour rule. Don’t let food sit out for more than two hours (or one hour if it’s a hot day over 90 degrees).
Toss the leftovers. The food will have been handled a lot, and possibly will have been sitting out for a while.
For tasty picnic ideas, see our Portable 4th of July Menu.