Abstract: A rigid polyisocyanurate foam suitable for holding stems of artificial flowers is a substantially closed cell foam having a density of about 1.7 to 2.9 lb./cu. ft. The foam is made by mixing components A and B in a ratio of B:A of about 0.2 to 0.6. Component B is a mixture of 100 parts by weight of polyester or polyether polyol, 0.5 to 5 parts by weight of potassium octoate, 4 to 10 parts by weight of water and 0 to 8 parts by weight of green colorant. Component B is mixed with 250 to 500 parts by weight of polymeric diphenyl methane diisocyanate (component A), and the resulting mixture is poured onto a substrate, which may be a conveyor or a mold box, for foaming in a substantially free rise step with a cream time of about 5 to 20 seconds. The conveyor is preferably heated to about 100.degree. to 150.degree. F. The foam is cured before cutting.