Who knew what a great houseplant keiki Cook and Norfolk pines can be!?

A few years ago, my mom bought a Cook pine at a fundraiser for $3 and now it only costs her labor and water. Kept in a pot on a table in her apartment, the happy and healthy tree gets bright light but not direct sunlight. She carries it to the sink to fully water it, and lets the water drain out the puka about once a week. The cool thing about growing a small one in a pot is that you can grow it for years without it getting very large. While festive at Christmastime, the potted trees are great all year long.

Norfolk vs. Cook pines

Although many people call them Norfolk pines, most of the trees in Hawaii are Cook pines. They are hard to tell apart, so don’t feel bad. Even a botanist or taxonomist must look closely at a mature one to know the difference.

Both are in the plant genus Araucaria. The Cook pine is native to New Caledonia, the Loyalty Islands and the Isle of Pines, and is scientifically known as Araucaria columnaris. Norfolk pines (Araucaria heterophylla) are native to Norfolk Island.

I asked my horticulture professor Dr. Richard Criley how to tell the difference between the two species.

“Most of our local Araucaria are the columnaris species (Cook pines), but there are a few heterophylla species around,” he said. “Trouble is you must have the fruits to tell the difference for sure. Even at the seedling stage, the tiny leaflets look alike and on the mature plant, the branchlets are also very similar.”

The Cook pine doesn’t produce a rounded crown at maturity like the Norfolk pine; the leaflets are also different on mature pines.

Check out the key and descriptions in the reference book “A Tropical Garden Flora” by George W. Staples and Derral R. Herbst. Staples and Herbst report in the book that Cook pines always grow on a slant, as was also reported in a 2017 study published in Ecology.

Growing local

Grow your own Cook or Norfolk pine tree or buy one from local growers. It’s the kind and akamai way for our islands.

If you want your potted pine to grow bigger and taller, give it more sun and fertilizer, and transplant it into successively larger pots. If you plant it in the ground, look up first. Make sure no wires are overhead, and that it’s not too close to your house or your neighbor’s.

As a certified arborist, I don’t recommend topping most trees, but with Norfolk or Cook pines it works well. After many years, when trees are getting too tall (like the one my husband, Clark, planted for his mom when he was 10 years old), you can trim it down to 20 to 30 feet and it will send up multiple perfect trees each year.

Harvest those to share with family and friends and keep the tree at a consistent, safe and easy-to-harvest height.

We did this for years at my folks’ house in Makiki. We had three pines and would rotate trimming the two big ones every year. If someone needed a tree and we had run out, we had a smaller “spare” tree to harvest from.

Mainland trees

One reason to use local trees (aside from the cost) is that imported mainland trees can bring alien pests in as hitchhikers. This is a major way we get all those invasive slugs, spiders, stinging yellow jackets and wasps. Not just pests to humans, yellow jackets can affect native Hawaiian wildlife.

The state Department of Agriculture has only enough quarantine inspectors to randomly inspect a sample of the trees that come to Hawaii in refrigerated containers.

Plus, mainland trees are drier and can become a fire hazard, while local ones are greener, fresher and more full of water.

If you do buy a mainland tree (I love the smell, too!), please check for pests. Put the tree on a white sheet and shake it out. Better yet, hose it down outside and look for slugs, wasps and even snakes. Capture and kill them.

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