Objective The study was performed to explore the effects of different substrate formulations on the growth of Bougainvillea in order to provide suitable cultivation mediums for Bougainvillea.

Method The two Bougainvillea cultivars'Miss Manila'and'Sao Paulo'were planted and seven kinds of raw materials including natural soil, compost, peat, sand, biochar, coconut coir and pearlite were mixed in different volume proportions to carry out cultivation experiment to study the growth of Bougainvillea under fifteen formula treatments and a natural soil control, respectively. The plant height, crown diameter, main, leaf SPAD values and NPK contents in leaf, and physical and chemical properties of culture substrates were determined, then the substrate formulas were comprehensively evaluated by principal component analysis, and the suitable cultivation mediums for the Bougainvillea was selected.

Result The plant height increases of Miss Manila and Sao Paulo under T12 were significantly higher than other treatments, which were 22.40 cm and 21.40 cm, respectively. The crown width increases of'Miss Manila'and'Sao Paulo'under T13 and T15 were significantly higher than other treatments, which was 25.20 cm, 23.45 cm and 33.85 cm, 35.85 cm, respectively. The SPAD and N content in leaves of Miss Manila and Sao Paulo under T13 and T15 were significantly higher than other treatments.

Conclusion The vegetative growth of Bougainvillea were well under T12 (soil∶compost∶peat∶river sand = 3∶3∶2∶2), T13 (soil∶compost∶biochar =3∶5∶2) and T15 (soil∶compost∶biochar∶perlite =∶3∶4∶1∶2), which were the optimal substrate formulas for the cultivation of Bougainvillea. Also, it was proved that green waste compost could substitute peat as the main substrate material, and the appropriate volume ratio was 40% to 50%. The addition of 10% and 20% of green waste biochar for cultivation of Bougainvillea showed significant effect.