I live in zone 6 and have a poncirus trifolate that I planted three years ago as a 1 year old seedling. The first winter it benefited from a neighboring perennial that leaned over and covered it throughout the winter, but has had no further protection since. Last year its trunk was buried in snow about 14 inches deep for weeks on end. It currently stands about 7 feet high and is in a southern exposure between an asphalt driveway and a white house. I neglected to plant my flying dragon seedling last summer, and by the time I remembered, it was too close to fall to expect a good result. I do fully intend to do so this spring. They can definitely thrive in a zone 6 climate. One year of protection, along with a well thought out location, is all that is necessary. The fruit, in my opinion, cannot get past your nose, so who would even consider placing them in their mouth? They are beautiful trees, however, and many a neighbor will stop and ask you about it. They will probably also walk away thinking that you are half crazy! lol I have mine for rootstock, because grafting is a goal of mine.

I don't know where I obtained this info, but I follow it with old seeds and have great luck. 1..Seeds from fresh, juicy fruit are best..shriveled fruit rarely produces seed that germinate. 2. Soak the seeds overnight in water. 3. Next day rinse and wash the seeds by simply running straight hot water (no cold water) from the sink over a strainer until the slime is gone. (This slim is part of the natural protection the seed has to protect it from the acid that is in the fruit.) 4. Immediately plant in good potting soil about one inch deep. No chilling is required. Chilling or letting them dry out will make them go dormant and they will take longer to germinate. 5. If you want to wait before planting, soak them in a solution of 1 tbsp of bleach to 1 gal. of water for 5-10 minutes. This will kill any mold and mildew. Then rinse them thoroughly. After rinsing, place them in pure peat moss that has been moistened slightly in a Ziploc vegetable or regular bag. Too much moisture and the seeds will rot. Refrigerate them. Do not freeze. They can be saved for 2-3 months in the refrigerator.seeds from fresh, 6. I have used old seeds and had no problem with germination, but i do soak them, then remove the outer shell off, then put them in tissue paper inside a plastic bag, in the heated propergator, most germinate, just not as qickly as fresh seeds, fresh you are talking a couple of days treated like this, ones i bought a year ago from tradewinds, take about 3 weeks , on delivery they were dry and looked quite old, they took about a week to 2 weeks back in march. (I place them between layer of dampened paper towel in the ziplock bag and put them on top of TV or fridge for the heat. I have great success with even old seeds.) 7. If you have any really old ones you need to germinate, you can soak overnight in a solution of GA3 to give a very good chance of germination. GA3=Gibberellic Acid or B1 also works Ken

Flying Dragon is a form of the Japanese Bitter Orange, Poncirus trifoliata, and regarding hardiness there is little or no difference between them. In cool climates Poncirus is deciduous and dormant over winter. The dormancy prevents significant growth of anything grafted on to it. This produces a certain amount of hardiness because new growth is the most sensitive to frost, and new spring growth will be delayed until the rootstock's dormancy is broken. However, in practice the effect is small and variable, and certainly doesn't turn citrus into a frost-hardy species.

Flying Dragon is one dwarfing variety of Poncirus trifoliata. There are several others available as rootstocks -- large-flowered and Rubidoux, to name two. They will produce a tree considerably larger than Flying Dragon, but still somewhat smaller than average for the genus Citrus understocks. But I'd not call them "dwarf" by any means. It really depends on your climate and the scion variety what their ultimate size will be.