i hope here are some people who can recommend me some nice looking tropical fruit trees which donīt need other trees to get fruits. i know allready theobroma cacao, Garcinia mangostana and Averrhoa carambola.
Andy, you might consider Lychee sinensis as well. It is a beautiful tree, with a wide umbrella shape as it matures. Shiny leaves. Mine does self-pollinate although I'm not sure if it requires insects to move the pollen. One of the comments here http://davesgarden.com/guides/pf/go/56532/ says they got it to set fruits in the greenhouse. My tree is about 12ft. tall and wide, at 8 years old. I have had fruit from it every year for 5 years although it alternates years for a heavy crop, then a light crop.
Um, how big is your greenhouse? All those trees get quite large. If you prune them too much, as in "bonsai" as your handle implies, you certainly won't get much bloom and no fruit.
The blooms on mango are not pretty, and smell terrible for about a month. They absolutely do require insects to pollinate.
i know Lychee sinensis, it is a very nice tree, but i didnīt know that it is able to make fruits without other trees. thank you for this recommend. i want to cultivate all my trees as bonsai. iīm well informed about this type of cultvation and about tropicl plants, but i donīt know much about the pollination of tropical fruit trees. i want only fruits on my trees when they are well branched and make fruits which have the right size for a bonsai. the fruits arenīt important for a long time, but it would be a shame if there wouldnīt be any fruits when the tree is well branches after many years. to bad that mango isnīt the right tree for my purpurse and that the flowers semell terrible. it is a very interesting tree and i like the fruits of it. i can use a big greenhouse of my grandmother for my tropical plants in the "warm" (the weather in germany is mostly bad and cold) season and in the winter they will be in my room.
Andy, most tropical fruit trees in my experience are big, vigorous and fast growing. I am having trouble with the idea that you can keep one small enough to live in a container, let alone bear fruit. Bonsai which basically stunts the growth of the plant by constant pruning will make this goal even less likely. Most fruit trees bear fruit on new or year-old growth and you will be cutting off any branch that gets big enough to fruit. Some varieties of citrus are bred to be "dwarf" but this still means at maturity the tree is 8ft. tall and wide, and has a large, heavy root system. I have a 5yr. old kumquat tree that is a dwarf and bears lovely scented blossoms and fruit twice a year. But it is already over 7ft tall.
I am pretty sure you will never get fruit if you keep the trees as bonsai. If you read up on large greenhouse displays like the Orangerie at Versailles, their fruit trees grow in large boxes that are moved into the greenhouse in winter so they still get humidity, warmth and lots of light all winter. The boxes are moved with a motorized forklift.
Also although we do get cool nights, and sometimes even frost here in winter, my tropical fruit trees bloom and set fruit in January to March - in fact my mango sometimes starts blooming in December - so the idea that you could keep a fruit tree in your room in winter won't fly unless you run a huge bank of artificial grow lights at least 8 hours a day. (to simulate a sunny tropical winter day) It might be more economical to heat your grandmother's greenhouse. The trees do not lose leaves and go dormant in winter like northern fruit trees so they need sun all year round.
Many like Carambola and Loquat bloom a couple of times a year as well. Loquat is another that self-pollinates, but again it has large leaves that would not be suited to bonsai culture. My neighbor has a beautiful old Loquat tree that bears fruit twice a year. The fruit is small, and the birds sow the seeds so I have loquat seedlings in my garden all the time. The pic below is a loquat seedling that has grown to over 4ft. in one year. On the closeup of the leaf, it is nearly 40cm. long. The other closeup is of the leaves of my Lychee.
Just my opinion, but I think Carambola or a dwarf citrus would be your best bet to keep a tropical fruit tree as a bonsai. Still, I doubt you'll get any fruit. On a citrus, at least you might get the beautifully scented flowers. On Carambola the flower sprays are on the trunk, so that might work on a bonsai. If it did, it sure would be pretty. http://davesgarden.com/guides/pf/showimage/272878/
thank you for your useful information and nice pictures. i know that i would need special lamps to cultivate plants in my room, iīm well informed about the needs of tropical plants. before i started to search for some nice tropical plants i informed me well about all their needs.
i can only use the greenhouse in the warm season, in the winter there are allready a lot of plants of my father and there is no more space for my plants. i will ask in a bonsai forum if there would be a problem to get fruits on the trees which only get some on older branches. iīm sure that it will work, but only with older trees wich are well branched. the cherry for example is one of the trees which should be a problem, but you can find a lot of pretty bonsais of it with fruits. carambola can be a beautiful bonsai : http://ibonsaiclub.forumotion.com/t6338-new-averrhoa-carambola-l-variety
thank you for your recommend, but i allready know both plants. citrus plants are very nice trees, but grows very slowly. i want to have some, but i didnīt find nice trees till now. there are allways grafted bad or are allready to big for my purpose. i will keep looking for some nice ones.
If you don't like the citrus you've seen, I wonder if you could try making your own? While citrus is often propagated by graft, it doesn't have to be -- it can be rooted from cuttings as well. You could buy an unsuitable citrus, and then use it as the "mother" to your bonsai.
Another citrus that will fruit in a relatively small pot -- Myrtle-leafed Orange (Citrus myrtifolia).
Outside the citrus family, how about Jerusalem Cherry (Solanum pseudocapsicum)? Its fruits are inedible (and somewhat poisonous) but they are very attractive. Plantfiles has a picture of a two year old bonsai here: http://davesgarden.com/guides/pf/showimage/127026/
i donīt have to buy an unsuitable citrus, my father have a few big plants. i will take some cuttings of them when we put them in the greenhouse in the fall. the citrus plants grow very slowly in our climate, i will still keep looking for a nice older plant. i donīt like the jerusalem cherry, but thank you for your recommend ;)