Yes - google each one and you will find information to help you be a success with these seeds.

Of course I already tried google. Didnôt find anything about sowing them anyway...
Isnôt there anyone who has sown these?
Would really appreciate any help. :)

You may have problems getting information as neither of these is very common. What I do if I can't find any information is find out where in the world these plants occur naturally. The Bauhinia is from China and the Grewia is S African. It's worth noting, however, that both species are found in mountainous regions so they are probably adapted to cold conditions. The Grewia is said to be hardy.
I would stratify (pre-chill) this seed before sowing it. Put it in damp sand, seal in a polythene bag and place in the fridge for 3-4 weeks. If your weather is still cold you could sow in pots out of doors still.
Another important factor is the size of the seed, as this will determine depth at which it should be sown. The larger the seed the deeper it needs to be. A rule of thumb is sow at the same depth as the diameter of the seed. If the seed is very small, sow on the surface and just press in. Good luck. - Ian.

Thank you for answering!
The Bauhinia I put in a glas filled with water two days ago. I already see changes with the seeds.
Today I planted it and have it about 20 degrees Celsius.

Grewia occidentalis I also have recently planted, and have it in the same place as the bauhinia, but if nothing comes up within 5-6 weeks I will definetly try to stratify those. :)