EFFECT OF UNDERGROUND HEATING AND COMPOST ON GROWTH OF FOLIAGE PLANTS
Mean measurements in mid-April showed that underground heating increased leaf number of plants in 100% peat compost by 25% and of plants in 80% peat: 20% polystyrene by 19%. At maturity in mid-June the increase with underground heating was respectively 27 and 25%. Leaf number of Dieffenbachia, Nephrolepis, Peperomia and Rhoicissus increased as much as 45% with underground heating, but that of Codiaeum, Dracaena, Hedera and Maranta increased by less than 10%. Ficus and Aphelandra increased 13 and 30% with base heat.
There was no growth advantage in amending the peat compost with polystyrene.