Okay, think back to a very cold January in your past. Did you have to pull out your "winter" jacket on that terrible day the temperature dropped to a frigid 40 degrees Fahrenheit? If the answer is yes, then you are geographically lucky and probably live in a climate where large reptiles could kill and eat you if you are not diligent. If the answer is no, you may live in the mid-west like me and can't grow citrus. So how does a gardener grow vitamin C in the mid-west? Plant a rose...
Rosa Rugosa is now found all over the world. It was introduced to the United States via New England in the 1770's. It quickly spread into the wild due to its ability to tolerate salt spray, ease of propagation and the fact that it is hardy down to USDA zone 2. It is considered invasive in many parts of the world. One of these days I will do a post on my position on "invasive" plants. Suffice it to say, I have Rosa Rugosa all over my property.
Most rose gardeners will dead head their roses to trick the plant into producing more flowers. With Rosa Rugosa you want to let the flowers fall off naturally. You will be left with these, the rose hip, also know as rose haw and rose hep. Rosa Rugosa has some of the largest rose hips of any rose. When they mature they are one of the highest concentrations of vitamin C in the plant kingdom. When dried, they have a 1-2 percent L-ascorbic acid (vitamin C) concentration, making them higher in vitamin C than citrus.
During WWII, German submarines were sinking many commercial ships around Great Britain making it very hard to get citrus. A campain was started in Britain to encourage the wild harvesting of rose hips to make a syrup for infants and children. Severe vitamin C deficiency is known as scurvy. There is a reason pirates (in the movies at least) use scurvy as a derogatory word, you don't want it!
Rose hips are packed full of lycopene, an antioxidant that prevents oxidation of LDL particles in your blood, that's a good thing. It also has vitamins B and A as well as essential fatty acids the body cannot produce for itself. Rose hip tea has traditionally been used to treat respiratory infections, joint pain and as a salve to treat sore mouths. Here is an abstract of a study concluding using rose hip powder benefits people with rheumatoid arthritis. Here is another study, same result for osteoarthritis.
Some care must be taken when eating them. Once the rose hip has ripened you can eat them raw by simply biting off the outside of the fruit. You don't want to pop one in your mouth and chew because they have seeds, and most importantly, fine sliver like hairs in the interior that have traditionally been used to make itching powder.
The internet is full of how to's on making rose hip tea, fruit leather, soup, jelly, jam, syrup etc... I will add that if you wait to harvest them until after the first frost, they will have more concentrated sugars. If you need one more reason to start growing this plant on your property, you can make wine out of it. What more do you want in a plant?