Industrial Hemp in Maryland is still illegal. In May 2015, a bill was signed into law legalizing Maryland Industrial Hemp contingent on the Federal Government passing the Federal Industrial Hemp Farming Act of 2015.  If the federal law or similar law passes, then beginning October 1, 2015, persons in Maryland may plant, grow, harvest, possess, sell or buy industrial hemp.

If the Federal Law is passed, the Maryland Industrial Hemp law will go into effect.

UPDATE: As of March 24, 2016 the Federal Industrial Hemp Farming Act of 2015 has not been passed and remains in Committee.

Maryland Industrial Hemp Definition

Industrial hemp is the plant Cannabis Sativa L. and any part of the that plant whether growing or not with a Delta 9 Tertahydrocannabinol concentration that does not exceed 0,3% on a dry weight basis.
If the Maryland Industrial Hemp bill becomes law then a grower will have to register with the Department of Agriculture.