The Feasibility of Grafting Hops on Grapevine Rootstock

Grafting is a common horticultural practice used to combine the beneficial traits of two different plants. However, the possibility of grafted hops onto a grapevine rootstock is highly improbable for several biological and practical reasons. This article explores the challenges and reasons behind this incompatibility.

Biological Constraints in Grafting

The success of grafting between two plants is contingent on their biological compatibility. Grafting is generally more successful within the same species, followed by the same genus, and then within the same family. Although there are commercially important exceptions, such as pears grafted onto quince (both in the rose family Rosaceae), attempts to graft between different families, let alone different orders, pose significant challenges.

Hops, belonging to the genus Humulus within the Cannabaceae family, are clearly distanced from grapes (genus Vitis, family Vitaceae) in terms of their biological relationships. Hops are not only in a different genus but also in a different family and order—Cannabaceae in Rosales and Vitaceae in Vitales, respectively.

Biological Reasons for Incompatibility

The anatomical and biochemical differences between plants from different families are substantial. Even though being in different genera, families, or orders does not inherently cause graft incompatibility, the significant evolutionary distance between hops and vines means there are likely to be anatomical or biochemical differences sufficient to cause grafting failure.

Practical Challenges

Aside from the biological incompatibility, practical challenges make grafting hops onto grapevine rootstock virtually impossible. Hops propagate through an underground rhizome, which is the overwintering structure and from which aboveground shoots grow each year. This lifecycle means that any hops shoot grafted onto a grapevine would likely die back to the graft union at the end of the first growing season. Rerooting and re-grafting would be necessary annually, which is logistically impractical and time-consuming.

Conclusion

The feasibility of grafting hops onto grapevine rootstock is constrained by both biological and practical considerations. While the practice of grafting within the same family, such as pear onto quince, is well-documented, the significant evolutionary distance and distinct biological characteristics of hops and grapes make such attempts highly unlikely to succeed.

For those interested in exploring new agricultural practices, it's essential to consider the biological and practical constraints involved. For now, the combination of hops and grapevines remains a theoretical curiosity rather than a practical agricultural technique.