Most of the “living Christmas trees” sold today really don’t do well indoors. (For more information on that subject, read Christmas Plants Too Good to be True.) Fortunately, there is at least one exception: the Norfolk Island pine (Araucaria heterophylla). Unlike a real pine or fir, it does very well in our homes. As long as you offer your little Norfolk Island pine some basic care, it can decorate your home for a decade or more.
Neither Pine nor Fir
This plant is not a pine (Pinus) and actually, to my mind, looks nothing like one. It could, however, be mistaken for a spruce (Picea) or a fir (Abies), given its very symmetrical habit, its branches that whorl around the trunk like the rays of a wheel, and its very short needles. Even so, it is none of the above, but instead belongs to an entirely different genus, Araucaria.
The genus Araucaria used to grow all over the world during the Jurassic and Cretaceous eras, sharing its space with the dinosaurs, but disappeared from the northern hemisphere about 65 million years ago, precisely at the same time as the dinosaurs did. Today, the genus survives in the wild only in the southern hemisphere. The remaining 19 species are found in South America, Australia, and, especially, the South Pacific islands.
Our species, A. heterophylla, is native to Norfolk Island, off the coast of Australia, and to two neighboring islands. In fact, one of the main industries of Norfolk island is harvesting seeds of Norfolk Island pine for export!
The vast majority of young Norfolk Island pines sold today are produced in Florida, then shipped around the world from there. It’s a popular houseplant in the North and also commonly planted outdoors as a large tree in subtropical climates where few other conifers succeed.
Although Northerners generally think of the Norfolk Island pine as a modestly sized houseplant, it’s actually a slow-growing giant. In the wild, it can reach 210 feet (65 meters) in height, the equivalent of a 20-story building! Given its upright habit and symmetrical growth, it was once considered for use as a ship’s mast, but its turns out that its wood is not strong enough for such a use. At maturity outdoors, it produces huge erect pineapplelike cones, but never indoors.
Growing Your Own Indoor Christmas Tree
The Norfolk Island pine is, unfortunately, often sold with 4 to 10 young plants, barely more than seedlings, crammed together in the same pot. That gives a denser effect more likely to appeal to potential buyers, but the resulting overcrowding is harmful to the plants themselves. Imagine, so many plantlets competing for the same resources, especially water and minerals! In fact, the main reason people fail with this plant is due to overcrowding! The best thing to do is therefore to either divide and repot the young plants individually or to cut off all but one at the base. For a fuller look, you could let 2 or 3 plants grow together for a while, but even so, after 7 to 8 years, the competition will become too intense and you ought to consider removing the extra plants, growing your Norfolk Island pine on its own, the way it does in the wild.
Other than that, the Norfolk Island pine is an easy-to-grow houseplant, that is, as long if you can provide it with a humid atmosphere during the winter. When the air is too dry, the stem tips tend to curl under, segments drop off and eventually entire lower branches fall away, leaving a very ungainly-looking plant. No amount of coddling will stimulate the plant to regrow new branches from its base (like most conifers, araucarias won’t produce new growth from mature wood) and you then have little choice but to replace the plant. For information on how to improve air humidity, read High Humidity = Happy Houseplants.
Once you’ve solved the humidity problem, you will find this little conifer remarkably easy to grow. It adapts readily to most medium to intense light situations and will even tolerate low light for months. As for watering, just follow the “golden rule of watering”: water thoroughly when the soil is dry to the touch.
This plant is not a heavy feeder: you can fertilize it at a quarter or one-eighth of the recommended rate using any fertilizer you have on hand. It’s best not to fertilize during the winter months.
The Norfolk Island pine prefers a relatively warm summer and a somewhat cooler winter, so would appreciate it if you lowered the thermostat at night during that season. It absolutely adores spending the summer outdoors in a spot protected from high winds.
Your Norfolk Island pine will grow slowly, putting out one new whorl of branches per year, and will eventually outgrow its pot. You’ll probably find it necessary to repot every 2 to 3 years, using ordinary potting soil.
When your Norfolk Island pine becomes too tall, which can take 10 to 20 years, you can keep it at a more reasonable height by pruning off the tip, which will force the plant to produce a new leader. By doing this regularly, you can pretty much keep in indefinitely at about the same height.
Forget it. This is one plant you’ll want to buy already started! It is generally grown from seed, but the seed doesn’t store well, as it must be fresh in order to germinate, and is therefore rarely available. It is theoretically possible multiply the Norfolk Island pine by cuttings, but secondary branches will not form a leader, but instead will continue to grow horizontally, creating a sort of unidirectional shrub. Only tip cuttings will give upright plants… and they’re not easy to root.
Pests and diseases
Under good conditions, the Norfolk Island pine is quite resistant to insects and disease. In dry air, though, red spider mites are a threat. They seem to come out of nowhere and cover the needles with their webs, sucking the sap out of its needles and causing yellowing and branch loss. Treat them by giving the plant a thorough shower.
For a Bit of Holiday Spirit
Yes, you can decorate your Norfolk Island pine for the holidays. Light-weight ornaments and garlands are fine, just avoid anything too heavy: the branches are not as sturdy as those of more typical Christmas trees like firs and may tear off if you overdo it.
You can light your tree as well, as long as you stick with modern bulbs, either LED or incandescent, as they give off too little heat to damage the plant. Avoid older types of incandescent bulbs, though, because the heat they give off can dry out the plant’s needles. If the bulb to the touch, it’s too hot to put on a living tree.
There you go: all you need to know to grow one of the few conifers that really does make a good houseplant. Let a Norfolk Island pine brighten your home not only this Christmas, but for many Christmases to come!