Hello Shmuel, Sinningia tubiflora and Sinninga sellovii both need full sun. I grow a large potful of S. tubiflora and have seen S. sellovii in the wild but do not grow it. It grew on black rocks in full sun and I wondered how the giant exposed tubers managed not to get cooked. Both are easy to distinguish: S. tubiflora produces lots and lots of small potato like tubers all linked together by stolons, this mass of tubers will fill the whole pot. S. sellovii pruduces a single big tuber on the surface of the compost. S. tubiflora is an easy plant to grow, it needs the same treatment you would give to a cactus, well, maybe more water in summer. Mine has become best after I put it onto automatic irrigation in summer. Full sun, heat (not quite sure about the heat in Jerusalem, but I would try) lots of water and fertilizer, and, yes a big pot. Mine does not really go dormant in autumn when it gets cool and rainy, so I chop off all shoots and keep the pot dry and cool in my cellar until spring. The compost is of no importance as long as it is fairly well draining and rich. S. tubiflora has long tubular, hence the name, white fragrant flowers. What it does not like is root disturbance. You can of course take apart the mass of tubers from time to time (I use a spade) but then it will be shy to flower that season. A plant grown in shade like other Sinningias would like it will become a semi creeping straggly monster without flowers. It took me a long time to understand that. All the best, greetings from partly flooded Germany Uli