My Norfolk Island pine is not doing so well; the needles are turning brown and the branches are drooping.
Why did this happen to my plant, and how can I cure it?
Click photos for full size
My (limited) understanding of Norfolk Pines is that they:
Are the branches drying out - it looks that way in the picture to me.
Did you recently re-pot it?
Are you perhaps over- or under-watering it it? We usually water our indoor plants once the top inch has dried and then water them until we see some water in the bottom tray.
What about fertilizer? There are indoor plant fertilizers and this plant might benefit from that if you aren't already giving it an occasional does of an appropriate fertilizer.
One thing about this tree that I read is that it really does best when it gets direct sunlight and enough moisture. The humidity level in most houses is going to be much lower than what the Norfolk Island Pine will want and so misting it often with a spray bottle will help. A humidifier would help too, though that is a bit more of an investment.
From here the Norfolk Island Pine likes
The ideal indoor climate for this species is bright and cool, with daytime temperatures ranging from 60 to 70 degrees and slightly cooler at night.
My experiences with this plant is that the dry conditions (relative humidity less than 40%) that are so common inside our houses are not ideal for this plant. Under less than ideal conditions it will drop lower branches as fast as it grows new ones from the top.
A south exposure is too hot in most locales and bright northern light is better in the Western hemisphere.
Wikipedia notes that
It grows well in deep sand, as long as it receives reliable water when young. This, and its tolerance of salt and wind, makes it ideal for coastal situations. Additionally, it is necessary for the species to be grown in oceanic coastal areas because bodies of fresh water do not provide enough precipitation, moisture, consistent wind levels and no saline air which are all things the species requires.
I do not agree that these plants need saline air but suspect that a sandy soil with constant access to moisture would be more successful than the common peat based soil and regular waterings. A wicking system as described in the link would be a low maintenance alternative.
I have grown these pines in home conditions for years. (Dry air, 72 temp. at a window with W/NW exposure.) Having said that and after reading the comments above, there is one thing I would like to mention after noticing the comments about repotting. I have a beautiful NIP in a tiny 4 inch pot that has thrived for many years. I have purposely left it in that pot because I didn't want it to get really large. It is 19" tall with a span of 36"! It sits almost directly under a ceiling vent winter and summer. In spite of all this it has thrived except for the height. So my point is that maybe it isn't so much the repotting that is the issue but TOO BIG OF A POT! I am certain that this pine would be double its size if it were in a six" pot but would be much harder to know exactly how much water it would need! I have other varieties of plants that are huge in TWO INCH pots. One of them even had a new plant appear recently that is now eight inches tall!! These plants blow my mind!
The bad news about Norfolk island pines is that they do not recover well. Once it has started to die and the needles become hard, the tree has a very slim chance of recovering. If this is the case, you may unfortunatly have to replace your plant. However they are relitivly easy plants to care for and require watering when the soil is dry. Best of luck with your plant.