Facts about Pittosporum Crassifolium
Pittosporum crassifolium is a small tree or large shrub, depending on how you look at it. It can vary anywhere from twelve to eighteen feet in height. The plant is native to New Zealand, and for the most part, is only found there and in China. In the United States, the only location with the pittosporum crassifolium is California. Its common name is karo pittosporum and the shrub is often referred to by just the shortened name of karo. Another name is stiffleaf cheesewood, and it’s often shortened to cheesewoods.
Karo has very thick leaves that are a nice, dark green and underneath they are gray and very fuzzy. The leaves are quite long and narrow, with a length of four inches and width of 1-½ inches. One of the most popular attributes of the karo shrub is the fact that it blooms profusely in early spring with reddish-purple flowers. Because the shrub has very thick clusters of flowers, the plant looks like it is covered from top to bottom.
Pittosporum crassifolium is not terribly fussy about the type of soil in which it is planted, as long as it is well-drained. It is not a plant which requires much attention, just a little bit of pruning in the summer. If the cheesewood gets completely overgrown, you can prune it back drastically and it will regrow successfully. If you want to grow more cheesewoods, they can be propagated by cuttings (with a heel) and root quite easily. They can also grow from seeds. The plant likes full sun unless where you live is very hot, and then it will need partial shade in the afternoon. It can only be grown in the United States in USDA zones 8-10.
If you decide to grow the cheesewood plant, be sure to get your seed from a reputable nursery or from a wild tree which you know as there are many different species of pittosporum crassifolium and it is well known that they hybridize with one another frequently. You can plant the seeds at the time when they ripen on the plant or keep them in a paper bag and plant in February. They usually have no germination problems. Place each of your seedlings in a separate pot and keep them in a cold frame until they can be planted in the spring.
Pittosporum crassifolium is a tree that is often grown in coastal areas and it has good tolerance to salt. The plant is often used as a hedge between properties and the ocean. It should be fertilized at least once a year, in the spring. The flowers will eventually turn to green seed pods and in the late fall, these split and the black seeds are carried about by the wind. This makes a feast for the birds.
There are a couple of different pests that feed on the pittosporum crassifolium. These are aphids and cottony cushion scales. Scales suck the sap out of the leaves, trunk, twigs and branches. The foliage starts to curl up and die. These scales also emit a type of sweet honeydew. This attracts ants and it can cause a black mold to form on the leaves of the tree.
The karo is a good source of saponins. These are not the type of saponins that can be eaten by humans or animals, but they are effective in deterring birds from eating plants. They have a very bitter taste but when used as a plant spray, are washed off easily by rain or a garden hose. Since these saponins are not edible, they are often used to make soap. In addition, the very dark, almost black seeds, are collected and used to make blue dye.
If you live in a warm location where the pittosporum crassifolium can be grown, you will find it to be an excellent tree that requires very little maintenance. If you live next to the ocean or other large body of water, this tree can be very useful as a windbreak.