Bougainvillea Plant Zone 7. It can withstand a light freeze but deep freezes will kill the roots. They thrive in USDA Zone 10 but will survive in Zone 9 if protected.
They can also be grown in the landscape if treated as an annual. The earliest that you can plant bougainvillea in Zone 7b is April. 08102019 Bougainvillea Plant Hardiness Zones Bougainvillea is a perennial only in the warm climates of USDA plant hardiness zones 9 through 11.
Can beetroot grow in tropical climates.
In zone 7 you will need to take them indoors over the winter. However you really should wait until May if you dont want to take any chances. They can also be grown in the landscape if treated as an annual. The last month that you can plant bougainvillea and expect a good harvest is probably August.