Lay the bark chips out on a large plastic tarp or drop cloth. Spread the bark chips in a single layer, so they are not piled up.
Fill a pump sprayer with wood sealer. Use a non-toxic, eco-friendly wood sealer. Once the shredded cedar is placed, non-toxic sealer will prevent any runoff from the cedar from releasing toxic chemicals into the soil. Do not use a pump sprayer with residual chemical substances to also avoid harming the soil or surrounding vegetation.
Pump the sprayer to build up adequate pressure. Pull the trigger and spray the shredded cedar with a fine mist, moving the nozzle over the cedar with slow, sweeping and slightly overlapping motions. While spraying, have a friend or family member stir and turn over the shredded cedar with a garden rake to ensure that all surfaces become covered.
Leave the wood sealer to dry, and then apply a second coat. A second coat will ensure a consistent, adequate barrier against moisture and sun. Allow the second coat to fully dry before spreading the shredded cedar in the garden. Lay the mulch on top of landscaping plastic.
Occasionally turn the cedar in the summer to keep sun exposure consistent on all sides, using a rake. Repaint the shredded cedar with a light coat of sealer a year later, in the springtime. It is possible to spray the cedar while it is in place in the garden, however, avoid spraying surrounding plants.