Those of us who grow vegetables year-round are really no different than those who grow seasonally other than we choose to grow varieties that - like us - brave the cold weather. Figuring out which varieties do well for us in our individual climates does take some experimentation. We can learn what works well for others by reading articles, blogs and of course participating in online discussion groups - but even then, what works for one person may not work for another.
Here in Marion, Indiana I have found the round Black Spanish Radish does quite well over winter - even in the open ground without protection. I love the dark black color of the skin - and the spicy taste of the flesh. Often though I find it necessary to remove the skin from these radishes before I eat them - it really depends on how tough the skin is - and you can tell by looking.
The ideal time to sow seeds of the Black Spanish Winter Radish is August or September. These radish do get larger than the typical round radishes you see in the stores. In fact, they are close to the size of a small turnip when they are ready to harvest. I find one radish is more than enough to use in an entire salad - and when I eat them sliced, the radish often lasts three to four days.
Adding a dash of salt seems to lessen the spiciness of this particular radish - but let me tell you, if you grow it during the summer, the radish is downright hot. So hot, in fact, I refuse to grow this variety during the summer months. Another thing I have noticed about this variety is - just like other radish - they do self-seed. If you've grown them and had them go to seed, head out to your garden this winter and look around to see if some are coming up on their own.
Once you acquire seeds of this particular variety, it is a good idea to save some seeds from the plants you grew. This is not the easiest radish seed to find. Saving radish seed is very easy - but you must be aware if you let more than one variety go to seed at the same time you do risk cross-pollination.
To save radish seed simply allow the plant to flower, make sure pollination is occuring (you will know it is if you see bees visiting the flowers), allow the flowers to remain on the plant once they have faded and soon you will see long pods forming where the flowers once were. Inside of these pods, seeds are forming. Allow them to remain on the plant until they begin to turn brown.
At this point, cover the seed pods with pantyhose and secure the pantyhose at the bottom with a twist-tie - just be gentle and make sure you do not pinch the plant stem in the process.
Once the seeds - and stems - are completely brown, cut the stem below the pantyhose, turn the entire bunch upside down and shake gently. Many of the seed pods may have popped open already and this will help shake those seeds down into the pantyhose and away from the twist-tie. Now you can untie the pantyhose and gently remove the stems and pods.
Place the dried plant material on a paper plate or screen and break open the seed pods that are still closed. Once you have gathered all the seeds, lay them out on a paper plate or screen to dry for about a week. Be sure to label them so you don't forget what they are. Once they are dry, put them into a container that already has a thin layer of dichotomous earth in the bottom of it (DE is a pest preventative) , place a label in or on the container and seal it. Store the container in a cool, dark, dry place.
That's all there is to saving radish seed. Remember that seed saved from your own garden is adapted to your local growing environment and thus is better able to withstand the growing conditions in your area and local pests.
If you want to know more, be sure to pick up a copy of The Complete Idiot's Guide to Seed Saving and Starting - and don't forget you can download a free sample chapter for your Kindle device.