Orchid seeds are very different from seeds of other flowering plants. Many orchid seeds
do not contain what is called endosperm.
The word "endosperm" breaks down into:
endo + sperm = inside + seed
Endosperm is basically the plant embryo's source of nutrition until it germinates into a little protocorm. Think of endosperm as the yolk sac of an egg.
The word "protocorm" breaks down into:
Prot/o + corm = first + trunk
It is basically a tiny little mass of mostly undifferentiated cells, that have root-like filaments, superficially resembling a true corm.
The Purple Fringed Orchid (
Platanthera grandiflora) is one of those orchids which seeds do not contain endosperm.
So how does the embryo within the seed obtain nutrients from it's environment...?
Through the invasion of a specific type or a group of specific type of fungi. These fungi are generally called mycorrhizae. Some of these mycorrhizae are associated with the germination of orchid seeds, some are not.
The word "mycorrhizae" breaks down into:
myco + rrhiza (
singular form of the word) = fungus + root
myco + rrhizae (
plural form of the word)= fungus + root
They are called mycorrhizae because these fungi are mostly found in symbiosis within the root structures of plants.
However...
Like I stated before, certain groups of mycorrhizae help in the germination of orchid seeds. Without these fungi, the orchid seeds that contain no endosperm are as good as dead.
Typically these fungi are not found just willy-nilly, they are found in somewhat specific environmental habitats.
So just, "sprinkling or broadcasting your
Platanthera grandiflora seeds just anywhere in your Southern California garden" is
absolutely useless, (it's not native to SoCal for a reason
).
In order to successfully germinate large numbers of
Platanthera grandiflora from seed, you'd need to
contact an orchid seed sowing lab that is well versed in germinating native terrestrial orchids from seed. Know that germinating epiphytical orchids from seed is MOST OF THE TIME, NOT THE SAME as germinating terrestrial orchids from seed. Certain protocol of germinating terrestrial orchids in-vitro may be the same as germinating epiphytical orchids from seed, but there are other sets of protocol that are slightly different but enough to make a difference; or there are certain sets of protocol that can be radically different from that of growing epiphytical orchids in-vitro. Germinating terrestrial orchids from seed can be exceptionally tricky sometimes (depends on the species), and if I'm not mistaken, the genus Platanthera falls in this category.
In the future, I'd be careful about buying orchid seeds. You really need to find out if you can find someone who either
can germinate the orchids you want from seed, or find someone with some experience in germinating other species of similar orchids from seed who would be willing to give a very strong and dedicated effort in trying the species of orchid you want to germinate from seed a try.
It is by no means impossible to grow
Platanthera grandiflora from seed, but it will not be like growing sunflowers from seed.
Good luck.