At Project Lemon Tree, we’re hard at work with partners University of Hawaii College of Tropical Agriculture & Human Resources (CTAHR), SOGA Organics from South Africa and Hokukano Ranch of Kona to find the best rootstocks for Lemons, Limes & Other Citrus in Hawai’i.

School Lemon Tree Plantings

Over the course of the last year, we’ve raised hundreds of rootstocks and grafted eureka and meyer lemon varieties for school planting projects. Just yesterday, we made a couple hundred more trees available to our school partners. The current 2019 cohort of new planting schools is 501 classes at 27 schools on all Hawaiian islands except Lanai (we’ll get the started soon too!).

Project Lemon Tree Orchards – Best Rootstock Research

We’re now diving into orchard production as several schools wish to plant at scale as do several ranchers. To do this responsibly, we’re engaged in determining best growing conditions, protocols and plant varieties. Says Mike Melzer of CTAHR, “Rootstocks are something… to experiment with since so much depends on the location, soil, irrigation.  Hawaii also has blight (like South Africa) so some people like to use less vigorous, but blight tolerant rootstock such as cleopatra.  However most new citrus grown in Hawaii is on a trifoliate hybrid rootstock since most of the trees are grafted in California (which doesn’t have blight).  These vigorous rootstocks are good for producing sooner after planting, but will experience higher losses to blight after about 8 years, so you can expect to reset a lot of trees – this can sometimes be a good thing for switching to more desirable varieties.  Florida has produced some rootstocks with good blight tolerance, but I don’t know of any planting in Hawaii with these rootstocks.  So bottom line is try several different rootstocks and see which emerges as the best for the location.

Stay tuned for more on this important research.