Hawaii Gardens: Deadheading plants boosts blooms and control pests

Question: What is deadheading and which Hawaii plants would benefit from it?

Answer: Deadheading is where you remove spent flowers to increase blooming and benefit the health of the plant.

Pua kenikeni comes to mind, as cutting or snapping off the green and orange “balls,” aka the developing fruit, will increase blooming.

Fruit formation and seed development takes a lot of time and energy for the plant.

So, if we want more flowers, don’t let the fruit form. In the case of pua kenikeni, the fruit on the stems makes for great decor in a flower arrangement. You can even string the “balls” into lei, as my lei-making buddy Dede Reiplinger Sutherland does.

Tiare, or Tahitian gardenia, nowadays needs deadheading. We didn’t use to have a pollinator for tiare but now it seems we do, as the old flower calyxes (the bottom green part of the flower) don’t fall off after blooming. They now form fruit and it takes about a year to fully develop and form mature seeds inside.

You should snap off that part on a daily or weekly basis or tiare plants will develop fruit and produce fewer blooms.

Tiare buds make an epic lei that can last for several days or nights with a most heavenly perfume. When you pick the buds, pick the calyx too and save yourself some time and energy.

My friend Donna Chuck has a prolific and sunny garden with many flowers for lei. She collects the tiare buds and stores them carefully in a plastic bag with a damp paper towel in the fridge until she has enough for a lei for a special someone.

We spent some time cleaning up and deadheading her plants and now she gets way more tiare flowers for her lei creations.

I first learned about deadheading when I was an apprentice gardener at Longwood Gardens in Pennsylvania during my junior year of college.

I was instructed by the horticulturist at Longwood: “Go deadhead the rhodies.”

Puzzled, I wondered if it had something to do with the Grateful Dead. I had to ask: What is deadheading? What are rhodies?

Rhodies are rhododendrons, related to the azaleas that we grow here. They bloomed massively in spring there and general good garden practice was to deadhead them in early summer, to promote lots of blossoms for the following spring show.

Some people use sharp needle nose clippers for this and others use sharp well-placed finger and thumbnails to snap off the spent blooms.

Roses are another plant that will bloom better if you deadhead, or you can just harvest and use every flower. If you let the fruit develop, you get rose hips which can be made into jam or tea.

Some kinds of hibiscus — especially our fragrant native white koki‘o ke‘oke‘o — will form seed pods if you let them. This is how early gardeners made new hybrids as they found the native Hawaiian whites were excellent “mother” plants. Again, if you want blossoms, pluck off and clean up the old flowers.

Another benefit to this is we have lots of recent alien insect pests such as scale and mealybugs. They love to hide in developing seed pods and suck sap and juices from the plants.

Deadheading helps you groom your plants, so you can rub or cut off the pest-infested parts. Get rid of insect eggs and small sap suckers before they form a full-on infestation.

Heidi Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.