Chills: Funny, we seem to have parallel interests with these plants. About 10 years ago, I did a trade with someone in Alabama, sent her some divisions of some of my native woodland plants for a box of ripe trifoliate orange fruit, because I really wanted to see what they were like. I found them most palatable. They were about the size of a small tangerine, and were quite seedy. The rind was bitter, but not any more so, IMO, than that of a grapefruit. Juice was quite sour but definitely citrus juice and very useable. I tried making a very small batch of marmelaide (spelling ???) by seperating the juice/pulp, and putting back just the zest of the peel, with the white pithy part, which contains the bitter substances, removed. It turned out just fine, or at least decent, to the best of my recollection. So, my conclusion is, if I could grow them, I could eat them. I have a big one, about six feet tall, in a pot. I've had it for probably six or 7 years now, but NEVER any sign of a flower bud. It winters indoors, though, and summers outside. Makes a very dramatic looking houseplant when bare of leaves in the winter, but also VERY painful to move around. The thorns are vicious. Dennis West Bloomfield

Yes, you can buy urea. Have you been told about the consequences? Everything that you did not write, I finished thinking for you, since I represent WHAT YOU NEED. I believe you should buy the least problematic fertilizer for the grower, and for the tree, in the long run. And, the effectiveness on the fruits is secondary. If you buy urea. - Urea causes strong branch growth. Do you want the tree even taller than it is now? - It is not known how Urea will act on boron. - Biuret 1% is a lot for citrus fruits. I don't know what the result will be. Biuret will probably hit the flowers hard, but at the same time it will hit the leaves ... You need to accurately calculate the dose. I don’t want to take it upon myself as to what dose is needed.

Orange, unless you choose to grow the way Steve is trying to help you out with, then I would go with Dave's advice...It's spot on.. Steve, I have to politely disagree. LIGHT is not EVERYTHING but is very critical factor and more so in your case at this time. Without your aeration methods, your plants would decline quite rapidly in the mixes you are using. It is the mixes we use, fertilizer we apply, light, watering habits, temps, bug sprays and the care that we put our plants through, the environment we provide that is 'everything'.. If I were to name one critical factor to start off with that is at the beginning of everything, then I would start with a good mix, then follow with good cultural practices.. I can tell you that every nursery owner that wants to see their plants thrive despite the ability to provide all the light they can get, invest thousands of dollars on the perfect mix for their plants, then sell it quite expensively.. I have seen some of the nicest plants quickly degenerate in poor mixes used in pots, despite all the sunlight provided. Yes, did you know that one can kill their planted trees in the ground with poor drainage, even if provided lots of sunlight? We have seen this demonstrated here? Therefore that is where people like John, Patty, Rhizo and many others come in to help out..If 'light' was everything, then growing citrus would be a piece of cake, a walk in the clouds, right? This post was edited by meyermike_1micha on Wed, Nov 6, 13 at 8:48

I have long been interested in Poncirus and have a website with details of European specimens. I'm not so familiar with US gardens, but have seen plants growing happily in New York and Boston botanic gardens. Geographically the plant in Edinburgh Botanic Garden, Scotland, is the furthest north I've located, but of course the climate is not so cold as yours. Searching US and Canadian botanic gardens and arboretums websites often fails to provide a database of plants. However, the Missouri Botanical Garden definitely has several plants growing outside and the Dawes Arboretum in Ohio lists a specimen of the dwarf form 'Flying Dragon'. Here in England I have once seen damage to smaller branches when the temperature fell to about +15F. This unexpected cold was after a period of much milder weather, and caused splits in the bark. Stating an exact hardiness is never very scientific. It all depends on variables such as duration of cold, humidity, wind, state of growth etc. Here is a link that might be useful: UK & European Poncirus specimens