Growing Cashew Trees for Hawaii

By Heidi Bornhorst

I found out writing this that you can eat the fruit of cashews and its high in vitamin C and good for your teeth and gums.

Linda Neumann who has a farm on Kaua’i helped me learn more.

It would be a pretty, and fun fruit tree to add to our gardens. Lots of other useful and yummy things come from Cashew trees.

For years we had a Cashew tree growing at Foster Botanic Garden. It’s in the Economic section of the garden. In this section we grow plants with various economic value or potential such as herbs, spices, medicines, food, and even poisons.

The main thing we were taught about cashews, is “Handle with extreme care”. If it is not ripe enough, or too ripe Abunai! (Danger in Japanese) It is hard, and possibly toxic to harvest and process the hard-shelled seeds (nuts). You need to harvest at just the right time, and then extract the seed carefully. Juice from the shell around the fruit may burn your skin.

That is why I’m happy to buy this heart healthy nut at the store!

Interestingly the toxic principles in the shell may make a good insecticide! Research continues.

The Latin name is Anacardium occidentale, (“Ana’ means upward, and “Cardium” refers to the heart). Cashew is in the Mango family, Anacardiaceae. Cashews are native to Brazil and Tropical America

Relatives include Fruit trees like Mango, Wi or Otaheite apple, Hog plum (my Honey’s favorite, one grows and Fruits in Foster Garden). Christmas berry tree is related. Poisonous relatives are poison ivy and sumac, and the Marking nut tree.

Flowers are greenish yellow, fragrant and grow in panicles. Bees like to visit and pollinate the flowers. The trees can grow up to 40 feet in ideal conditions, we usually find shorter, wider trees here in Hawaii.

The fruit and nut are very interesting to see. The “fruit” that catches our eye is actually a “false fruit” or pseudocarp. Some call this a “cashew apple” Being Eurocentric they called all kinds of tropical fruits “apples”!

The actual fruit (botanically speaking) of the cashew tree is a yellow or red kidney shaped drupe that grows at the end of the cashew apple. The drupe develops first on the tree, and then the pedicel expands to become the cashew apple. The true fruit contains a single seed, which is generally considered to be a nut.

Aren’t plants wonderful and Complex?!

The attractive colorful and juicy fruit is an adaptation to attract fruit eating animals to aid in seed dispersal.

Although it is perishable, we can eat the fruit and make value added products like wine and fruit roll ups.

Cashew trees favor well drained soils and regular watering to get established. The flowers like it dry, just like mangoes. They benefit from leafy mulch. Keep turf grass well away from the root zone.

Today it is mainly grown commercially in Brazil and India. We do have some intrepid farmers in Hawaii who are growing trees and even selling products. I salute their courage. Farming and marketing etc., is not easy!

Recently my friend Kaui Lucas, who is a Trained Permaculturist, was talking to me about her Cashew keiki trees. She showed me these cute and vigorous keiki, that she is growing on her sunny lanai, protected with chicken wire.

Lucas got an email from the Department of Agriculture about a seed giveaway from Hinshaw Farms. She said “Frank Hinshaw is the cashew guy. He invited me to go visit, we could make a holoholo day out of that ! Super sweet guy and he was so helpful. The farm is at “Poamoho”.

A few years ago, My Friend Elizabeth Reigels and I went on a kalo and farm kokua, Gourmet Foodie and Educational event and on the Reppun farm. We visited a gorgeous tree that was loaded with ripe fruit. The fruit are very pretty and interesting to see.

This tree was so attractive and productive that it got me thinking cashew might be a viable crop for backyard growers and even for diverse mixed Fruit tree farms.

This would maybe be a good crop to grow more of in Hawaii. Especially if we grew it like old-time Hawaii farmers did, and like Permaculture and Regenerative Agroforestry plant scientists do now.

That is, grow a diversity of tree species, not a single Monoculture or plantation style. Layers of tall and short trees, shrubs, and groundcovers all grown together. Leave the leaves and let them naturally decompose and enliven the soil.

This diversity keeps the plants and soil health and helps capture rainwater and let it percolate down to our aquifer. It’s also more enjoyable to work in the Diverse cool shady spaces, cultivate and harvest than in a Monoculture, plantation, chemical using style of tree farming.

Besides eating cashews raw, roasted or salted, have you ever had cashew cheese? It is a bit labor and time intensive to make but it is so creamy and delicious. And it has less of some of the less healthy parts of yummy cheese: no cholesterol (since it is from a plant) and only healthy nut fats.

There is a farm in Moloa`a on Kauai with more than 200 Cashew trees. Linda and Scott Neuman started in 2002, are learning about which varieties grow best and how to harvest, dry and roast. Check them out online and buy some of their locally grown products. The Farm is called Neu Mana Hui farm.

They have an abundance of other crops too, including figs. Interestingly they used a ‘chicken tractor’, a mobile coop that lets the chicken’s control, and eat weedy grass and fertilize trees and crops too. Akamai, no?!

The oil around the nut is toxic and needs to be handled with care.

As Neumann says: “Our farm has 2 employees: my husband and myself. We do all the planting maintenance and production of our product. I have spent a lot of time trying to educate on the “toxic” product….

People get confused. Old school way is to throw the nuts into a fire and then crack to get inside. That smoke is toxic.

The cashew is fruit where the seed grows outside the fruit. The nut is the seed. The seed itself is covered by testa a covering like you see on a peanut. That protects it from CSL fluid which is in between the exterior shell and the testa. (cashew seed liquid)

That substance is used for many products in paint, brake fluid and other products. Some methods of processing capture the CSL we do not. The CSL will peel the skin on your hands.

We use gloves when handling the shells. A lot of people ask about growing cashew, cashew grow well in most areas of Hawaii, but the equipment is costly and difficult to obtain.”

The CSL fluid, or cashew seed liquid, and it has insecticidal properties (Makes sense no, since it would protect the seed from insects and grazing munching herbivores).

Traditionally the nuts would be thrown on a fire and smoked open. This smoke extremely toxic.

There is now an expensive machine to open the nuts safely. The Neumann’s do this and don’t bother with the seed oil

BUT what a diverse and useful crop for Hawaii’s future as we wean ourselves off toxic tourism. 30,000 visitors a day is way too many. Let us grow some nuts instead, and support local farmers, chefs, and True value-added businesses.