I dont know what PPFD/DLI numbers are. Bit from my own experience, and I live in zone 9b, in a pretty humid subtropical climate( usually). When I have planted them i the ground, then they've become established, they have been very able to thrive in dry conditions. Both almost no rain for a half a year on end and low humidity. In other words, we've had unusually dry conditions for the past year and a half and they still thrive, aside from chickens eating them.