Note 10 - Convertible Notes Payable - Related Parties - Convertible Notes Payable to Related Parties (Details) - Convertible Debt Payable to Related Party [Member] - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Long-term Debt, gross	$ 1,048,164	$ 2,558,681
Less unamortized debt discount	11,730	0
Long-term Debt	1,036,434	2,558,681
Bill Chaaban, President of Cen Biotech [Member]
Long-term Debt, gross	0	1,388,122
Director, Harold Aubrey de Lavenu [Member]
Long-term Debt, gross	878,368	878,368
Joseph Byrne [Member]
Long-term Debt, gross	121,796	224,191
Jeff Thomas [Member]
Long-term Debt, gross	48,000	0
Director, Alex Tarrabain [Member]
Long-term Debt, gross	0	48,000
Brother of Director Ameen Ferris [Member]
Long-term Debt, gross	$ 0	$ 20,000