A new book out in 2005 published by Hyland House which I borrowed from our library and can highly recommend. “Just Nuts” by Allen Gilbert who lives on Bruny Island, Tasmania. Anyway, take a look at the book as I found it interesting. A number of nut trees available to us in the sub-tropics are featured along with other more temperate types. Now I know that perhaps one of the reasons why our Pecan hasn’t set well for the last 5 years: It says the climate is too warm!
Also mentioned in Allen’s book was the Quandong Santalum acuminalum which needs a host plant in order to propagate. Because of the parasitism needs of the Quandong, propagation has been difficult and it is only recently that there has been some success using a common grass species for the developing seedling to parasitise. However, the seeds can be germinated quite readily before being placed with a host plant.
Propagating the Quandong plant can be done using uncracked nuts but one of the problems has been the amount of bacterial and fungal organisms adhering to the shell surface or naturally occurring in soil mixes; these often infect the developing seedling or tend to cause the kernel to rot. For best results it is best to crack open the nut, extract the seed and then clean it thoroughly with a bleach or antiseptic material before rinsing with pure, clean water.
Put the seed in a sterile medium (steam if necessary) such as palm peat, perlite or peat moss insided a plastic bag or in a pot and place the container in a warm, dark place. Allen has used a sealed plastic bag containing damp but not wet peat moss and placed the plant material in it with good results. Seed germination can also be assisted with the use of plant auxins such as Gibberellic Acid but these materials are not readily available to home gardeners. Seeds (kernels) should germinate within 3-8 weeks of sowing and can then be transferred to pots. Whole seeds may take over one year to germinate as the seed coat has to break down and there may also be some seed germination inhibitors within the shell that prevent fast germination.
Once germinated the young plants are best transferred into a pot containing the root of another plant as a host. I’d never read what the host was exactly but Allen says that couch grass and lucerne are two plants that have been used in pots containing the seedlings. The potting mix used should be low in phosphate as too much will kill the plant. The developing roots are very sensitive and care must be taken when transferring the germinating seedling in the pot. The pots used to grow plants should be deep, not squat, as the roots of seedlings are vigorous and grow deeply.
Once seedlings have developed, they can be grafted with a selected scion cultivar but because the stems of the plant are usually thin, some grafting methods are unsuitable. In the wild, Quandongs grow by seeding so there is naturally a large variation within the species.