Join the Prospect Park Alliance for Mulchfest! Bring your holiday tree, minus the decorations, to Prospect Park, where we'll turn it into environment-friendly mulch that can be taken home for your own yard or garden. Volunteer! Help assist in removing ornaments and distributing mulch. MulchFest in Prospect Park is presented in partnership with NYC Parks, Park Slope Civic Council, NYC Department of Sanitation and GreeNYC.