Rinse the elderberry clusters and pat dry. Remove any leaves, green berries (which are toxic), or large parts of the stem.

For easy destemmping, put the whole cluster on a baking sheet and freeze them until solid. Once they're frozen, the berries will easily come off the stems without making a juicy mess.

After destemming the elderberries, portion them out into freezer bags or containers so they are ready for your recipe. Seal the bag and get as much air out as possible. Flatten the bags for easier stacking and thawing. Put the bags back in the freezer.

Frozen elderberries keep up to 6–12 months without quality loss. Make sure you label the bags with the date and the portion, so you can make sure to use the older berries first. If you want your elderberries to last a little longer in the freezer, vacuum seal them to prevent freezer burn.

Spread the berries into a single layer on your dehydrator tray. If your trays have larger holes, you can put parchment paper over them so the berries don't roll off or fall through. Dehydrate at about 135º for about 8 hours, or until they are completely dry.

If you're using an oven, turn the oven to its lowest setting and crack the door to make sure there's good airflow. Dry for 6-8 hours, checking periodically to check for doneness.

Dried elderberries should be brittle and hard, not sticky at all. If they are squishy or leathery, keep drying. If you break one of the berries open, there should be no moisture inside.

Once the berries are completely dry, store them in glass jars or vacuum-sealed bags, something that is air-tight. Keep them in a cool, dark place to preserve the potency of the berry. You can use oxygen absorbers to extend the shelf life.

Dehydrated elderberries can last 1 year or longer if they are kept very dry and airtight.