Enjoy the flower while it lasts; there may not be another for many years. Have a look at the thread One year old grapefruit tree with flower | UBC Botanical Garden Forums.
I for one, will keep my fingers crossed that this little tree will bloom again - soon. It's currently in the midst of a big growth spurt.
Zero is a bit definite. I find mother nature presents us with infinite possibilities. Where one flower grew - another is sure to follow. Personally, I have seen a grapefruit (indoor grown only) plant that was about 18" tall that produced several flowers and then produced a fruit (my friend pollinated one of the flowers with the use of a small artists' paintbrush). Needless to say, the plant could not support the weight of the fruit by itself and my friend had to prop it up with sticks. I'd imagine that the fruit would likely have not been very tasty since it was grown indoors.
to grow citrus fruits, you can often lessen the time taken to germinate by carefully peeling off the outer skin-like layer on the seed using your fingernails. do it right after youve harvested the seeds, dont let them dry out. citrus seeds are also very likely to rot from fungus if theyre too wet, so limit moisture. i successfully germinated a grapefruit in a small peat-pellet i kept damp in my closet, it took about two weeks. you can also use the damp papertowel method, where you peel the skin off the seeds, and place them in folded up, damn papertowel. place it in a slightly-open plastic ziplock, inthe sun if you like, and wait a few weeks. do NOT overwater, damp, not soggy. also, dont let the seeds dry out, as this reduces the viability of the seeds quite a bit. good luck!
