(1 Gallon) Igloo Viburnum is a deciduous shrub that produces masses of beautiful white 4" lacecap flower clusters in May giving it the appearance of an igloo. (1 Gallon) Igloo Viburnum is a deciduous shrub that produces masses of beautiful white 4" lacecap flower clusters in May giving it the appearance of an igloo. The plant sets good quantities of scarlet-red fruit. It is a wide spreading, yet compact, dome shaped plant full and dense right to the ground. Full Sun to Part Shade Shade tolerant Height: 6-8 feet Spread: 10 Feet Zone 5 - 9