Epiphyllum seeds will need to be grown in a container like this, something with a close-fitting lid that will keep the humidity high (100 %) and prevent the seedlings from drying out.
Fill your container nearly full with a fine-textured potting soil. Newly germinated epiphyllum seedlings are tiny and therefore have a tough time coping with large chunks of potting medium. Imagine a tiny seedling that has sprouted beneath a big chunk of fir bark, for example. It must push this huge piece of material aside before it can reach the surface. The potting soil I used here consisted of approximately equal parts of commercial potting soil (with the big chunks screened out), number 3 perlite (the fine stuff), and very fine worm castings. When the container is nearly full, even the surface with something flat. Here I am using the flat side of a four-inch plastic pot. Press lightly. The object here is to even the surface, not to compress the potting soil.
Set your hose nozzle on its MIST setting.
Wet the potting soil using the mist setting of your nozzle. That’s correct; you are watering the soil BEFORE sowing the seeds into the container. You want to use the mist setting so you don’t mess up the nice smooth soil surface you’ve just made. Water thoroughly so that water drains from the drainage holes in the bottom of the container.
Scatter the epiphyllum seeds over the surface of the wet potting soil. Try to distribute them as evenly as you can so that there are not some areas where the seedlings will be tightly clumped together and other areas that will be devoid of seedlings.
Cover the seeds with a top dressing of the same potting soil you used to fill the container. The seeds should be covered only to a depth of about one eighth of an inch, certainly no more than a quarter inch.
After top dressing, smooth the surface of the potting soil a second time in the same way you did before. The object here is to make sure that the top layer of soil in making good contact with the seeds. Again, don’t compress the potting soil, just even the surface.
Using the mist setting again, wet the top layer of potting soil. This should only take a couple of light passes with the hose, since the top layer is thin, and the rest of the potting medium in the container is already wet. This will prevent washing the tiny seeds too deeply into the potting soil where they may never germinate.
Label the container with the names of the parent plant or plants of the seedlings and the date the seeds were sown.
Cover the container. Locate in a mainly shady place where the seedlings can receive some dappled sunlight. New epiphyllum seedlings cannot be allowed to dry out. Since the container is covered, the potting soil will dry out only very slowly. You may have to water (using the mist setting again) only once every several weeks.
These are seven-week-old (from sowing) epiphyllum seedlings in a flat. The cover has been removed temporarily for this photograph. Seedlings should remain covered until they are a few inches tall or are touching the top of the cover.
Here is a tight cluster of tiny epiphyllum seedlings in a flat. Ideally you want to get the seeds farther apart than this. These will be somewhat difficult to separate when it comes time for transplanting as their roots may become intertwined.
This is a newly germinated epiphyllum seedling showing its twin cotyledons (seed leaves). In this greatly enlarged photograph, the big white boulders are actually pieces of number 3 perlite. Because of the high humidity in the covered container you will notice some green algae growth on the surface of the potting soil. This is especially noticeable on the pieces of white perlite. This does no harm to the epiphyllum seedlings.
This is a young epiphyllum seedling sporting its very first spine. They grow up so fast! *sniff* Note the discarded seed coat at the base of the seedling on the left.
This is an epiphyllum seedling that is a little further along in its development. Note the several areoles with spines on the incipient juvenile stem. The shiny black object that looks like an insect is actually the seed coat still adhering to one of the seed leaves.
This is a seedling that has developed a little further still. The juvenile stem is elongating as the distance between the areoles is increasing.
This is the same flat of seedlings pictured above, this time at 14 weeks old. Again, the flat cover has been removed to take this photograph. The seedlings have grown in height, with several reaching the top edge of the flat.