Gardening : They’re Nuts About Macadamia Trees

<i> Sidnam is an avid gardener and writer who lives in Orange County. </i>

Although macadamia nuts are most often associated with Hawaii, the trees originally came from Australia, and they will thrive and produce in many Southern California climatic zones.

The handsome trees are evergreen with attractive dark-green foliage. In early spring, the trees are covered with long clusters of white, pink or yellow blossoms. In recent years, the trees have become favorites of landscape designers in their edible-landscape projects.

Macadamia-nut trees will grow well and produce in any area where avocados produce well. Although macadamia trees favor the coastal avocado-belt regions, they will produce satisfactorily in inland regions where temperatures don’t go below 26 degrees Fahrenheit or some frost protection is afforded.

Will Grow 30 Feet High


The tree will reach a height of 30 feet and spread from 15 to 20 feet. The macadamia is a long-lived tree that begins nut production five to seven years after planting. Depending upon variety, nuts reach harvest stage from fall through late winter.

Macadamia trees are available in two species, Macadamia tetraphylla , which has spiny leaves and rough-shelled nuts, and Macadamia integrifolia , which has smooth-shelled nuts and smooth leaves. M. integrifolia produces best in coastal regions, while M. tetraphylla is a better choice for inland areas.

When purchasing a macadamia tree, it is best to purchase only a tree that has been grafted and is a named variety. Beaumont and Cate are both good producers and among the more commonly available varieties.

The trees are becoming more available in local nurseries as demand for them increases. If you can’t find the trees in Los Angeles County, nurseries in San Diego County, especially around Fallbrook, Vista and Chula Vista, are likely to have them in stock. Pacific Tree Farms, 4301 Lynwood Drive, Chula Vista 92010, phone (619) 422-2400, usually has a good supply of macadamia trees.


Self-Fertile Trees

Macadamia trees make best growth in a good, deep, well-draining soil. The planting site should be an area that receives full sun. Allow for 20x20-foot spacing when selecting your planting area. Macadamias are self-fertile and don’t require another tree for cross-pollination.

When planting, dig a hole twice as wide as the root system, but only as deep as the tree was originally grown. Test the soil for proper drainage by filling the planting hole with water. Let the water completely drain and then fill it again. If the water does not drain out within 12 hours, choose another planting site or refer to a soil guide for correction methods. Improper drainage is the primary reason young trees don’t survive. After testing, place the tree in the planting hole and refill the hole with the soil you originally removed.

Planting time is a good time to add slow-release fertilizer tablets. Tablets such as Osomcote Planting Tablets or Jobe’s Tree Spikes will provide long-term nutrient release without burning the roots. They are also ideal for fertilizing established trees. Follow label directions carefully. To assure the roots’ moisture, water during the planting process.


After planting, if there is no rain, water the new trees two times a week, or daily during Santa Ana winds or hot spells, for the first six weeks. Then establish a weekly (in absence of rain) watering routine. A deep watering is necessary; however, avoid soaking the lower trunk area for an extended period of time. This can be accomplished by trickle irrigation.

Young trees should be staked, and they will benefit greatly by some type of wind protection. The macadamia tree usually is pruned to a central leader system. However, the tree will do fine with little pruning other than for shaping and removal of dead branches.

Ripe Nuts

The nuts grow in clusters like grapes and fall to the ground when ripe. They never should be picked from the tree, as they are not fully ripe until they fall of their own accord. The husks, which are similar to walnut husks, should be removed and the nuts should be dried in the sun for two weeks.


Next comes the really tough job--cracking and shelling the nuts. If you have ever tried to crack a macadamia nut, you have discovered that they are the toughest of all nuts to shell. Many a finger has been smashed in the process of cracking macadamia nuts. They are probably best cracked with a hand nut cracker--a long and tedious process. However, if you buy a special macadamia nut cracker, the task becomes easier. Macadamia nuts are delicious raw or they may be roasted and salted.