Yes, the flavor is lacking -- edible, but nothing very exciting. It's grown and used basically as a garnish because of its exotic appearance. I think the flesh/pulp scooped from the outer shell could be juiced and then mixed with other juices, herbs, spices, flavorings and be pretty decent. But, just wanted to comment, I grew some quite a few years back from the seeds scooped from a grocery store kiwano. It's closely related to cucumbers, the vine looks about the same, grows the same, and is incredibly productive. Even here in my relatively short growing season (roughly 5 months frost free), they developed many fully ripened fruit. I think I grew three or four plants, and probably got 70 or 80 fruits total -- a big pile of them. I never thought, at the time, to slice one open when very young and see if it could be eaten as a cucumber, or perhaps even pickled like a French cornichon when very, very tiny.

I tried to find an online source for plants for you, but didn't. Basically, they are a cucumber, and the seedlings would be pretty fragile and not something shipped too easily via mail order, although companies like Burpee do ship vegetable plants (prices are pretty outrageous, though). I also saw how much the couple of online vendors are charging for seeds. I had to laugh at one -- 3 seeds, "RARE!!!" for a total of about $7 with shipping on an Amazon.com vendor. Yeah, they're as rare as you local supermarket. For $3, a supermarket kiwano probably has, I'm guessing, at least 500 seeds. I'm sorry you had bad luck with your recent attempt. The seeds actually should germinate really fast, in about 3 to 5 days, if conditions are right, moist and soil temp in the mid 70's. Maybe the seed you got was old, so it lacked vigor. Maybe the germination conditions weren't quite right. I would suggest you go buy a kiwano at the grocery store and try again, they are actually super easy to grow, if you can grow a cucumber or a tomato plant you can grow a kiwano. And, if you're in one of the warmer climates, I would think you have a pretty long window of opportunity until frost, so no problem there as they actually only take about 90 days to maturity at most, possibly less.

Here's one paper that reported fruit formation but no viable seeds: Euphytica 128(3): 371-374 (January 2002) Incompatibility in diploid and tetraploid crosses of Cucumis sativus and Cucumis metuliferus S. Alan Walters1 and Todd C. Wehner2 (1) Department of Plant, Soil, and General Agriculture, Southern Illinois University, Carbondale, IL, 62901-4415, U.S.A (2) Department of Horticultural Science, North Carolina State University, Raleigh, NC, 27695-7609, U.S.A Abstract  The African horned cucumber (Cucumis metuliferus Naud.; 2x = 2n = 24) contains genes that can confer resistance to many important cucumber (C. sativus L.; 2x = 2n = 14) pests [e.g., root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood]. Cucumber is highly susceptible to this root-knot nematode species, and a recent screening of C. sativus accessions in the U.S. National Plant Germplasm collection did not identify sources of resistance. Thus, autotetraploids of Cucumis sativus and C. metuliferus were created to recover fertile resistant interspecific progeny. Autotetraploids were obtained at the highest rate when seeds were immersed in 0.5% colchicine for a period of 6 to 8 hrs. Treatment durations less than 6 hrs produced few tetraploids, and durations of 10 hrs or more were lethal to seeds or developing seedlings. Crosses between C. sativus and C.metuliferus were made using diploid and tetraploid lines in all possible combinations, including reciprocals. Fruit development occurred in crosses when diploid and tetraploid C. sativus were used as the female parent. However, seeds developed only in fruit of C. sativus (4n) ÃC. metuliferus (2n) crossings. Seeds from these crosses, however, were flat and not viable. No fruit development occurred in crosses where C. metuliferus was used as the female parent. Success was achieved (apparently -- I haven't read the article) by making somatic hybrids -- fusing cells from two species. Cucurbit Genetics Cooperative Report No. 14, July 1991 Selective methods for the recovery of somatic hybrids of Cucumis melo x C. metuliferus and C. sativus x C. metuliferus M. Dabauza, L.A. Roig and V. Moreno (Spain) Karl

I grew some from seed down here in Atlanta. I took the seeds and threw them in a pot with some other plants. Suprisingly, the vine grew extremely fast and by the winter, I had a kiwano fruit. Kiwano's are not demanding but very invasive. If you keep it trimmed throughout the spring and summer, you will have time to see a couple of fruits form. Good luck!