THCa flower is legal federally because of how the 2018 Farm Bill defined hemp.
The 2018 Farm Bill changed the definition of marijuana into two completely different legal materials. One: marijuana has 0.3% Delta-9 THC or more. All other cannabis with less than 0.3% Delta-9 THC is legally hemp under federal law.
THCa flower qualifies as hemp because:
Cannabis doesn’t even make Delta-9 THC. It makes THCa — tetrahydrocannabinolic acid — which only becomes Delta-9 when it’s heated or ages (a process called decarboxylation).
So as long as the Delta-9 THC content is below 0.3% by dry weight, the product — even if it's high-potency THCa flower — is considered legal hemp, not marijuana.
You basically get your dank weed, test it so it shows less than 0.3% Delta-9 THC, market it as hemp, and it’s legal under the Farm Bill.
The 2018 law also provides legal protections:
The Farm Bill has explicit protections against interference with interstate commerce in the newly legal hemp market.
That’s why companies — including THCa Valley, a major THCa brand — can legally ship THCa flower directly to consumers in non-legal states.