The Marijuana Investor Summit was not short on speakers and panelists offering advice on financing a cannabis business. But many cannabis entrepreneurs learned a grittier lesson in the conference center’s labyrinth-like hallways and the hotel’s lobby bar: don’t rely on venture capitalists to finance your early-stage business.

Venture capitalists and angel investors are often seeking investment opportunities that fit within the boundaries of a checklist: an ancillary business that doesn’t “touch the plant,” a scalable market, and a viable, short-term, exit strategy with large potential returns. A few deals were closed over the three-day conference, but some entrepreneurs went home empty-handed, despite gleaming Powerpoint presentations and elaborate vendor displays.

But entrepreneurs shouldn’t lose hope: the future of financing for the cannabis industry might be on their computer screens. Various methods of crowdfunding were mentioned throughout the summit and are proving to be a valuable source of interim funding and seed capital...