Hydrangeas are Tennessee’s favorite late-summer blooming shrub. They are also a research subject at the Otis L. Floyd Nursery Research Center with over 100 varieities on property.

Dr. Lisa Alexander, plant rreeding project leader at the research center, shared these facts with the McMinnville Garden Club at its August meeting: 

• Two native species - the oakleaf and the smooth leaf or Annabelle - are understory shrubs with white, inconspicuous flowers. Only in Southeast Tennessee do these two grow side-by-side. 

• From 23 species, over 1,200 varieties of hydrangea have been developed. The two visual “styles” are the mophead, a native of Japan that produces large floppy blooms, and the lacecap, with a less compact garden-cottage bloom. Depending on sun and water, there is a hydrangea for every spot in your landscape. 

• The oakleaf likes acidic soil and is pruned after flowering but, ideally, by Sept. 1.  The smooth leaf is pruned anytime during the year. Some favorite oakleafs are Ruby Slipper, the industry standard, and Munchkin, a smaller variety. Pruning time depends on whether the plant blooms on the stem or on the tip of the stem.  

• A “reblooming,” or remontant hydrangea, blooms on both stems and the tip of the stem. Favorite rebloomers are Mini Penny, Let’s Dance, Nantucket Blue and Endless Summer or any of the series with these names.

Dr. Alexander predicts “we will see more and more remontant cultivars hit the market. Some will re-flower as well or better as Endless Summer; others will disappoint. Eventually we will see a wide range of well-performing remontant cultivars in a wide range of inflorescence forms, flower colors, plant habits, etc.”

Dr. Alexander recently returned from Japan where she shared her successful research on the DNA of the hydrangea. Hydrangea research at the center includes genetics and breeding as well as sustainable production.  The research center is a facility dedicated to the improvement of the Tennessee nursery industry. 

Tip of the Month: Hydrangeas sold at florists and supermarkets are not for landscape planting. 

For questions or feedback contact us at McMinnvilleTN GardenClub@gmail.com