Seed germination methods

I guess I'm not alone in being confused when trying to find germination instructions for obscure plants online. A lot of extremely specific, mutually contradictory sets of instructions, without references to source, is frequently all you find. Or maybe an entry on Plants for a Future, which is quite often contradicting itself, since it's often made up of quotes from different written sources, few of which are probably first-hand accounts. If you're lucky, there might be a research paper of some sort, where they might include the germination method used for a given species of plant in the methods and materials section. Anyway, finding anything sometimes requires quite a lot of scrolling and comparing different sources to try and find common points. This is tiresome, and I've found myself wishing for a place where people share strictly first-hand experience of methods used to germinate seeds of specific species, in an accessible way. And what better place to find this kind of information than Permies? This thread does not appear to exist yet (or if it does I didn't find it) so here we go.

I'd like this to be a place for first-hand experience only, so no reference to what someone else quoted some third person as saying. Just what you did, and how it worked. Also, for accessibility, it'd be good to limit ourselves to methods that actually produced at least some germination. Yes, I know, a negative result is also a result, but there are so many possible reasons for failed germination that have nothing to do with the method used (bad seeds from shady Ebay seller, a specific bacterium in the soil, etc) that the negatives mostly aren't very useful. On the other hand, mostly (but not entirely) negative results can be very useful indeed, especially if you have some indication of why most of the seeds failed to germinate.

Also, for clarity, remember to inlude the scientific name of the plant, since a common name can sometimes be used for more than one species.

So, that's more or less my idea. I'll start:

I usually follow the instructions on the seed packets because there are so many different variables when it comes to planting seeds.

All I know to do when planting a seed that I don't have a seed packet is to use a rule of thumb such as planting seeds at a depth equal to two or three times their width.

Most of the seeds I plant are very tiny, so my method has been to put them in a spice jar with tiny holes, and then sprinkle the seeds on the ground.

I then use seed starter mix that I shift with a strainer over the seeds.

My seeds seem to germinate best if planted in the ground outside.

If starting seeds inside I like to use the paper towel method to germinate the seeds.

Xanthoceras sorbifolium - yellowhorn

I've made four attempts at growing this plant from seeds, and results have improved for each attempt. The current method is as follows:
-Use sandpaper to polish off some of the shiny, blackish surface of each seed. Not all the way in to the white endosperm, just so that there is a lighter brown patch where some of the shine is taken off. The patch doesn't need to be large.
-Put seeds in a glass of water in room temperature for 1-2 days. The seeds will start out floating, but will soon absorb water and sink. After one or two days all of them will probably have sunk.
-Sow in a mix of soil from a coniferous forest, sand and standard potting soil (I don't know the best ratio, but I suspect it's good to have plenty of the first two ingredients, see below). Put the seed with one of the flat sides down, and push it down into the soil until the top of the seed is level with, or just above, the soil surface. Keep the pot in room temperature (germination occurs at lower temperatures too, but is way slower).

The first time I tried to grow yellowhorn, I used a mix of standard potting soil and sand, without coniferous forest soil. Some seeds germinated, but then immediately molded.

The second time, I don't remember the soil mix, but I did the whole process outdoors, in cold and frequently rainy weather. Two seeds germinated and grew a tiny bit, but the roots seemed to have trouble going into the soil (which wasn't extremely compact) and the root tip died. After a while both plants died. I suspect the rain and cold was too much for them.

The third time I tried, I used plenty of conifer forest soil and sand in the mix (don't know exact ratio). I did the entire growing outdoors, in the summer (sometimes cool but never cold, and no excessive amounts of rain). I planted four seeds. Two germinated, one of the plants had its root tip die before the shoot was visible, the other grew well but rather slowly, and should still be alive unless the winter cold killed it.

The fourth growing, I again used a mix of conifer forest soil, sand and standard potting soil. Nine seeds were planted in room temperature. Two of them have grown spectacularly, were replanted today, less than a month after sowing, because their roots were already at the bottom of the pot. Three more have germinated. One of them has recently started showing a shoot. The other two had the root tip die (one because the root grew above the soil and dried out) but I buried the ends of the roots, and lo and behold, they made new root tips!

I believe that yellowhorn will never have awesome germination rates. The tendency of the root tip to die is one reason for this, but there are also a lot of seeds that just don't germinate. One thing I observed is that the seeds where I polished away the shell all the way into the endosperm didn't germinate (I guess since they were invaded by bacteria through the hole and rotted) Also, I do believe that they prefer a somewhat acidic soil.

Actinidia kolomikta - arctic kiwi

I tried growing these twice, once with bought seed (zero germination) and once with fresh seed that was never allowed to dry out. With the fresh seed I got good germination.
Starting from fruits, the method I used was as follows:
-Mash fruits in a jar of water. Let it sit in room temperature for a few days to ferment so that the fruit pulp releases from the seeds. The seeds will sink to the bottom. Shaking the jar may help. Carefully pour off water with suspended pulp. Rub the seeds if there's still pulp adhering to them, and rinse again.
-Warm stratification (room temperature) for two months, then cold (fridge) for three months. Since the seeds are rather small, it might be good to either stratify in moist paper, or if you use sand, use a smaller quantity so the seeds don't get lost in massive amounts of sand.
-Sow in room temperature.