Jennifer Schultz Nelson
Extension Educator, Horticulture
Perhaps you were given or decided to buy a Norfolk Island pine for Christmas this year. Often they are marketed pre-decorated, making it hard to resist as a living Christmas tree. But what do you do with it after Christmas?
Despite its name, the Norfolk Island pine is not a pine. Its Latin name is Araucaria heterophylla (synonym A. excelsa). They are members of an ancient plant family of conifers named Araucariaceae. During the Jurassic and Cretaceous periods this was an incredibly diverse family of plants, existing nearly worldwide. At the end of the Cretaceous period, dinosaurs became extinct, and so did the Araucariaceae family of plants in the Northern hemisphere.
The Araucariaceae continued to thrive in the Southern hemisphere. Within the family are three genera containing a total of 41 species. One of these genera is Araucaria, which contains the Norfolk Island pine, Araucaria heterophylla.
Is there really a Norfolk Island? Yes, it's not made up. Norfolk Island is located in the South Pacific between Australia, New Zealand, and New Caledonia. It is an Australian territory, and its flag prominently features the Norfolk Island pine.
In its native island habitat, the Norfolk Island pine bears little resemblance to the potted plants offered for sale here in Illinois. They are slow growers, but over time easily reach heights of over 150 or even 200 feet, with trunks up to 10 feet in diameter! They maintain their distinct symmetrical shape throughout their lifetime despite high winds that distort other species.
They produce fairly large cones, nearly five inches long and wide. When the cones mature, they release seeds which are nut-like and edible.
Norfolk Island pines have evolved to be very tolerant of high salt concentrations in soil. This trait is essential to its survival on coastal regions of Norfolk Island. It can also grow well in very sandy soil, again an advantage in coastal regions.
High salt tolerance can be thought of as a benefit in being grown as a houseplant as well. The Norfolk Island pine should tolerate salt buildup from fertilizers quite well. This is not to mean you should over-fertilize, or let salts build up excessively, but the tolerable window is a bit larger for the Norfolk Island pine. So you have more time to correct growing conditions than with some other plants.
As timber, Norfolk Island pines are pretty weak. Hawaiians use the tree as material for woodturning, a decorative art which carves wood turned on a lathe. The fact that Norfolk Island pines tend to grow with very straight trunks is probably one reason they are used for this craft.
As a landscape tree, Norfolk Island pines are generally very resilient in the face of high winds. However, they are severely sensitive to frost, and damage caused by frost will weaken the tree. Typically, a tree so weakened will produce multiple weak trunks which cannot tolerate high winds. In places where hurricanes are common, some towns have limited or prohibited the use of Norfolk Island pines in the landscape.
Interestingly, one place where Norfolk Island pines are very undesirable as landscape trees, South Florida, is also the major producer of seedlings for the houseplant industry. In many cases the trees are spray painted to make them extra-green and sold decorated as holiday trees. To some, these are "disposable plants" that will be discarded after the holidays. With a little knowledge and care, this doesn't have to be the case.
A critical need of the Norfolk Island pine that often gets forgotten is light. They need as much bright indirect light as you can give them. They can tolerate lower light levels, but need to be acclimated over time to lower levels. Moving a plant from bright light to low light all at once may cause entire branches to die and drop from the plant.
This concept has led to many a discussion with my husband, as while he may find the "perfect" place for a plant in our house, he sometimes forgets that plants need light. A dark corner doesn't cut it. I'll never forget my sister asking me to figure out what was wrong with one of her plants. I went over to check it out, and found an extremely dead plant in a dimly lit room. The plant had looked so nice on her table, she hadn't thought about the plant needing light.
A rule of thumb with all houseplants, not just Norfolk Island pine is that they will grow best in conditions mimicking their native environment. Light is one of the more obvious needs. One that is probably the most misunderstood is water and humidity.
Norfolk Island pines typically grow in coastal regions, which are by nature very humid environments. When placed in our usually dry winter homes, Norfolk Island pines need some extra humidity. This doesn't mean water more. Norfolk Island pines are not very tolerant of wet feet. Considering they thrive in sandy soil, which by nature drains well, this is not all that surprising.
Increasing humidity can be done by filling a saucer with water and rocks or gravel, and placing the plant on top without the pot touching the water. This creates a microclimate of higher humidity around the plant. For a larger group of plants, consider using a humidifier. The Norfolk Island pine and many other houseplants will appreciate the effort.
High humidity also discourages a common houseplant pest, the spider mite. It takes some practice to recognize, but early infestations show up as speckling or stippling on the leaf, with mites hiding on the underside. Advanced cases demonstrate how these mites got their name, as the plant is slowly engulfed in webby material. While they can be treated with a variety of insecticidal soaps and other treatments indoors, increasing humidity is a relatively simple way to prevent problems with this pest.
A typical symptom of a Norfolk Island pine in distress is loss of the lower branches. Some loss of lower branches is also typical of a maturing tree, but excessive loss is definitely a red flag. Unfortunately, the branches won't grow back. If this happens, check the growing conditions. Most likely there is something amiss with either the available light, too much or too little moisture.
In extreme cases, I've seen Norfolk Island pines with long snaking main trunks bare except for a tuft of new growth at the tip. It is possible to cut back a plant that has lost its lower branches, but realize this will permanently distort the plant, and will likely result in a multi-stemmed plant. In my opinion, healthy multi-stemmed growth will look a lot better than what you started with.
In any case, a Norfolk Island pine will be around for many Christmases to come with a little care and attention given to their growing conditions. I bought mine in a four inch pot during high school, and it is still alive and kicking, now in a 12 inch pot. At various times it has served as my Christmas tree. It is a little worse for wear after suffering a period of low light that I couldn't avoid–right now it looks like Charlie Brown's tree. But I can't bring myself to get rid of it, as there are a lot of memories tied up in that tree!