Over the past 30 yr, rockwool culture became one of the principal techniques for growing vine crops, especially tomatoes, cucumbers, and peppers. Commercial stone wool production started in Denmark in 1937 with the Rockwool Group. In 1949, they started manufacturing rockwool in the Netherlands. Grodan, a subsidiary of the Rockwool Group, was founded in 1969 to research the potential use of stone wool as a substrate in horticulture industry. In 1979, Grodan began commercial production of rockwool for horticultural use in the Netherlands. Grodan is now established in over 60 countries worldwide.