I'm rather new to trying tropical trees myself, so take me as the last word in what I have to say here.

I've tried Blue Jacaranda and Tabebuia Chrysostricha. The Blue Jacaranda germinated, but only about half of them and the mortality rate of the saplings has now been 100 per cent. Had four that were doing good and suddenly, they died. The Tabebuia seeds never germinated.

I've been lucky in that I am simultaneously planting a lot of other seeds this year, some wonderfully successful, like my Cassia alatas and my Phoenix dactyliferas ( Date Palms ).

One truth about seeds is that some are just plain easy to germinate. Others are stubborn.

But there are apparently other things about seeds that everyone aspiring for a green thumb should know ...

1.) I am absolutely marvelled to learn that seeds sense stress in their environment and refuse to germinate except under ideal conditions. Ideal conditions may depend upon temperature, dryness or wetness, Ph values, soil type and even temperature transitions from winter cold to spring warmth and oddly enough, lack of sun light or shade and alternatively, plenty of sun light.

2.) It would seem that some seeds may have long dormancy periods and others need to be sown immediately after they are produced by their parent plants or the embryos die.

3.) In regard to 2.), some seeds though they don't necessarily require long dormancy, can remain dormant for an incredibly long time. Recently, an archaeological expedition in the middle east found some ancient palms seeds and after trying to germinate what was thought to be an extinct species of date palm, they were met with success and revived the species!

4.) Seeds may be destroyed in situ, either before or after sowing by a variety of factors which include storage in excessive heat, excessive watering, root rot, bird or other animal piracy of the seeds or saplings, insect infections, mold and environmental stresses from too high or too low a temperature, too little or too much light, poor soil, not enough nutrients and so forth.

5.) Sterile seeds that may be produced, but were never properly pollinated or suffer other defects.

That's a lot to take account of. I note that most cultivated plants, plants that people have taken a hand at, tend to be faster and more certain germinators, but may germinate into conditions of stress because the seeds did not have the capability to wait for ideal conditions. That's not usually a problem.

However the seeds you purchase may already be embryonically dead or be a bad batch of infertile or defective seeds. Sometimes, you will receive about 30 seeds and they'll tell you that it's enough to grow 12 plants. You might want to read up on shelf life of the species of seed you are working with. Also read up in greater detail on environmental factors and what ideal conditions are for the seeds.

I recently planted cactus seeds. They came up instantly, but if they were taken out into sunlight, they would die. Why the heck would a desert plant die in sunlight? Because they naturally germinate in winter, under cooler and cloudier conditions and by the time spring and summer come around, they are established enough to bear the more difficult environment. As seedlings, direct summer sun will bleach them white in just a couple hours.

It's a difficult thing understanding germination for some plants. I'm still scratch'n my head and experimenting.

I suggest that you don't plant all your seeds at once and reserve most of them while you try a small number in your prevailing conditions and then if you are met with failure, adjust the environment based on what you can learn from other people's experiences or write-ups and try again.

Often, it may be necessary to germinate seeds indoors under artificially created and monitored conditions and then put them out into the real world once they become established. I would say that for most seeds, direct sunlight can be a problem. UV light kills bacteria, mold and as I have had opportunity to note, infant plants. Make good with the shade!

I recently started some Pride of Barbados and Royal Poinciana seeds outside, but in pots and they germinated fairly quickly. Did you nick and soak the seeds first? If not try doing that. I use an infant nail clipper to nick the seed coat. I've never tried a Strawberry tree.
Karyn