Three porous materials (growstone, expanded clay and activated carbon) were evaluated as hydroponic growing media and for their individual ability to remove the indoor volatile organic compound formaldehyde under three conditions: growing medium alone, dry medium in a pot, and wet medium in a pot. The total percent-reduction of formaldehyde by each growing media was evaluated over a 10-h period. In all cases, activated carbon achieved the highest removal under the three conditions studied with average percent reductions measured at about 98%. Four common interior plants: Hedera helix (English ivy), Chrysanthemum morifolium (pot mum), Dieffenbachia compacta (dump cane) and Epipremnum aureum (golden pathos) growing in growstone were then tested for their ability to remove formaldehyde. The removal capacity of the aerial plant parts (AP), the root zone (RZ) and the entire plant (EP) growing in growstone were determined by exposing the relevant parts to gaseous formaldehyde (∼2000 μg m −3) in a closed chamber over a 24-h period. The removal efficiency between species and plant parts were compared by determining the time interval required to decrease about 2/3 of the total formaldehyde concentration reduction, T 2/3. The T 2/3 measured were 23, 30, 34 and 56 min for EP of C. morifolium, E. aureum, D. compacta and H. helix, respectively. The formaldehyde removal by the root zone was found to be more rapid than the removal by the aerial plant parts. ► The four plant species demonstrated similar abilities to remove formaldehyde. ► The T 2/3 determined for each species was significantly different. ► Activated carbon showed highest formaldehyde removal under all conditions studied. ► All plant species showed faster uptake of formaldehyde under dark cycle conditions.