In the jar, you'll need to use dried ingredients rather than fresh ones. When done this way, your stovetop potpourri will last as long as your dried spices and herbs are good for. Generally, ground spices last 1-2 years and dried herbs last up to 3. The date of your oldest spice in the blend is how long it will be good for.u003cbr/u003eu003cbr/u003eBut because you won’t be consuming the spices, it’s also okay to use old spices. The younger the spices, however, the more fragrant it will be.u003cbr/u003eu003cbr/u003eOnce boiled, your potpourri can last 3-4 days as long as you keep topping up the water. Never leave it unattended!