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The Honolulu Advertiser
Posted on: Friday, June 28, 2002

Rainbow shower tree is a Hawai'i stunner

• A special tea for your plants
• What's in season

By Heidi Bornhorst

The rainbow shower tree is a hybrid of species imported from India and Indonesia. The tree blooms from March to November and was designated Honolulu's official street tree in 1965.

Deborah Booker • The Honolulu Advertiser

Columnist's note: Aloha, readers!

Today this column is in a new format designed to serve you better.

I'll answer a reader's question, plus feed you an interesting gardening-related tidbit and a note about what's in season in Hawai'i. We hope you like the change.

Dear Heidi: Where did the rainbow shower tree come from?

— Scott Nagata, 'Aiea

Dear Scott: The rainbow shower tree — recognizable by its bounty of multicolored blossoms — is a "made in Hawai'i" hybrid. It's also the official street tree of Honolulu, so designated in 1965 by then-Mayor Neal Blaisdell.

The two parent species of shower trees were brought to Hawai'i from far away: The golden shower, Cassia fistula, hails from India. The pink-and-white shower, Cassia javanica, was imported from the Indonesian islands of Java and Sumatra.

Being a hybrid, the rainbow shower usually doesn't set seed and must be professionally propagated by air-layering.

A sure sign of summer in Hawai'i is the blooming of the rainbow shower, which can be found on all inhabited islands but is particularly prevalent on O'ahu.

It is a less-thirsty tree, is very tough and adaptable, and has a long blooming period, from March to November, with a peak in the summer. Some beautiful ones grow in Kapi'olani Park, along King Street, along the H-1 Freeway near School Street and Nu'uanu, and in many parks and gardens.

The original tree of the variety called Wilhelmina Tenney, with deep watermelon-pink and yellow blossoms, grows on the Daibutsu terrace area of Foster Botanical Garden. It was a gift from Tenney to Dr. Harold Lyon, the first director of Foster Botanical Garden.

There is a Queen's Medical Center white variety, also known as Queen's White, which is a pale-yellow to white form of the rainbow shower. Many of these are along the freeway near Foster Garden, as well as near the fountain in Kapi'olani Park.

One of my favorite shower trees is the Nii Gold, named after Shigeki Nii, founder of the famed R.S. Nii nurseries in Hawai'i Kai. This is a deep golden-yellow with rich apricot shades and a delightful, subtle perfume. Judy Nii, who manages the nursery today with her husband Richard (Richard is Shigeki's son), says that it's a sport of the Wilhelmina Tenney tree growing in their nursery.

Do you have or know of a great rainbow shower tree? Please write to me about it and send pictures.

Heidi Bornhorst is director of Honolulu's botanical gardens. Reach her at islandlife@honoluluadvertiser.com. or at The Advertiser, P.O. Box 3110, Honolulu, HI 96802. Letters submitted to The Advertiser may be published or distributed in print, electronic or other forms.

• • •

A special tea for your plants

Soon you'll be able to find compost tea made by local recyclers on your garden-store shelf. But you can also make your own tonic for your seedlings, transplants and any plant that looks off-color: Put compost or manure in an old rice bag, burlap sack or pillowcase.ÊSoak in a bucket of water for two to three days.ÊDilute the resulting tea with three parts of water for every one part of tea before using. (You also can put the compost back on the compost pile or around a plant that needs a little help.)

• • •

What's in season

Royal poinciana, also known as flamboyant, can be found in fiery red, golden orange and, sometimes, even yellow. Check this out all over the Islands.ÊLots of glorious ones are in older landscapes in Napili on Maui, on Kamehameha Street in Manoa, and on Alohea Avenue in Kapahulu.