Industrial Hemp seeds (Cannabis sativa cv Kompolti) were sown in the midrow of a vineyard in Marlborough, New Zealand to assess the effects of companion planting hemp with grapevines on the vines and the vineyard soil. The hemp become established without supplemental irrigation, even in an exceptionally dry season when other cover crops failed to thrive. The presence of hemp did not negatively affect vine nutrition, water relations, growth, or yield. Soils from the hemp treatment had higher organic matter, soil carbon, and cation exchange capacity. Hemp plants grew roots to at least 30 cm, and were able to grow in compacted tractor wheel tracks in the row, where the root system can alleviate compaction caused by vineyard operations. Juice/must samples from the 2019 harvest, when hemp was also grown in the vineyard, showed a higher diversity of yeast species than the control, and produced a better wine.
The results of the first season of this 3 year study show that hemp is a viable cover crop for New Zealand vineyards. The presence of hemp in the vineyards provides a means of alleviating soil compaction, addition of organic matter to the soil without negatively affecting the vines, and a potential second income stream for the grower. The hemp did not have a negative effect on the wines, and actually improved quality compared with a wine from grapes not grown alongside hemp.