Legend has it the Delphic oracle told Apollo, The radish is worth its weight in lead, the beet its weight in silver, the horseradish its weight in gold.
Horseradish (Cochlearia Armoracia) is a Brassica like cabbage, broccoli, kohlrabi, wasabi and mustard, and is one of the bitter herbs eaten during the feast of the Passover. This common name, horseradish, means a coarse radish rather than the edible garden radish (R. sativus). It is the readily vaporized oil in horseradish that sears our tongues and brings tears to our eyes. That oil dissipates quickly when exposed to heat and air, which is why true horseradish lovers prefer their horseradish freshly grated.
I can personally attest that fresh horseradish can be deceiving to the taste. The year my sister got married, money was tight so Mother hosted the wedding rehearsal dinner at home. Early in the afternoon, she made the cocktail sauce for the shrimp appetizer with freshly ground horseradish, and kept adding horseradish until she thought the taste was just right. I was salivating at the thought of the first bite of an ice-cold cooked shrimp dipped in that ‘perfect’ cocktail sauce... but when it finally came, the heat of the horseradish in the sauce had intensified. That first bite almost blew my taste buds right out through my brain! Nearly forty years later, my sinuses and eyes can still tear at the memory.
One tablespoon of horseradish has only six calories and zero fat. The National Heart, Lung, and Blood Institute recommends horseradish as part of a healthy, low-fat diet because of its fat-free, high-flavor qualities.
In the U.S. an estimated 24 million pounds of horseradish roots are ground and processed annually to produce approximately 6 million gallons of prepared horseradish, enough for sandwiches with horseradish on them to reach 12 times around the world.
Historically, horseradish has been used as a stimulant and laboratory tests show it to be antiseptic. Internally horseradish stimulates the digestive organs and helps complete digestion. Too much can have the effect of an emetic or a laxative. An infusion of horseradish was used to treat dropsy (swelling of soft tissue from water retention). Because of the antiseptic and diuretic effects, horseradish has been used for centuries to treat kidney stones and bladder infections. “For bladder infections, mix 3-4 tablespoons of the fresh grated root with apple cider vinegar and honey to taste. Take the whole amount throughout the day.” 
A teaspoon of horseradish in half a glass of water after meals was used for chronic rheumatism. Horseradish eaten frequently during the day is said to be an effective expectorant, helpful in getting rid of a cough following the flu and for sinus infections. It was sometimes used for mild scurvy.
Externally, horseradish stimulates the skin (also causing redness) and its scraped roots are used like a mustard plaster. It makes a good rub for low back pain. Scraped roots were also said to cure chilbains when applied and covered with a light bandage. An infusion of horseradish in milk makes an excellent cosmetic skin cleanser. I’m told that here in the South, horseradish was rubbed on the forehead to relieve headaches, and some folks still swear by it.
The enzyme horseradish peroxidase, found in this plant, is used extensively in molecular biology for antibody detection, among other things. It is increasingly important in biochemical research fields. 
This root will grow in zones 3a-9b in full sun and it will tolerate some partial shade. It usually grows 12-24” tall in loose, fertile soil, but can get much taller. Since the roots are very cold-hardy, they may be planted in February if the ground can be dug. Choose straight young roots with a crown (or growing point), cut off all side roots and plant 12” deep. Other than needing a rich soil and occasional weeding, horseradish is a care-free plant.
After the first fall frost killing the leaves, the roots may be dug and divided although you may harvest some smaller roots in summer. Discard any old, woody roots and replant a few young sturdy roots. I always heard to harvest horseradish roots in months containing an “r” (September to April). In severe winters you should heavily mulch the horseradish plants. The dug roots may be stored whole like beets in a root cellar, or taken to the kitchen to be prepared. (See preparation under culinary use, below.) My grandfather stored his roots in dry sand or peat moss in the crawl space under his house if the basement was full or too warm.
Caution: Horseradish is like comfrey and will grow from the smallest piece of root left in the ground so choose your planting spot carefully.
If you enjoy horseradish, you are going to love homegrown, freshly grated horseradish!
Horseradish is high in Vitamin C, potassium, calcium, magnesium and phosphorus as well as volatile oils. The easiest way to preserve horseradish is to grate it. Use caution when grating, the fumes are pungent and will irritate your eyes and make your sinuses drain! If you are using a blender, chop the peeled roots into small dice, and add some ice water and/or ice cubes to the blender. Mix grated horseradish immediately with white vinegar (or lemon juice as a substitute) and maybe a tad of salt. You can use beet juice to make red prepared horseradish.
The hotness of prepared horseradish is a matter of when to add the vinegar since the vinegar stops the enzyme action in the ground horseradish, and how finely it is ground. Like garlic, the finer the cells are chopped or ground, the hotter. Experiment until you get the degree of heat you want. This ‘prepared horseradish’ will keep for 4-6 months tightly covered and refrigerated (or longer in the freezer). When it begins to darken with age, toss it away, dig out a fresh root and make some new!
You can spice up store-bought potato salad, cole slaw, baked beans and other deli items with a touch of horseradish mixed in. Use it in place of salt and butter on roasted corn to reduce fats and cholesterol. Or make a ‘butter’ to use on veggies by mixing ½ cup softened butter, 1 cup plain lowfat yogurt, 1 tsp. prepared mustard and 2 tsp. prepared horseradish.
Mix horseradish with cream cheese then spread on thinly sliced rare roast beef and wrap around tender but still crispy asparagus spears for a delightful appetizer. Mix prepared horseradish and a touch of mustard with apricot preserves for a great ham glaze. Or add horseradish to applesauce for pork dishes.
The classic horseradish sauce for beef dishes is made by whipping heavy cream until stiff, and folding in fresh grated horseradish to taste.
Note: When serving horseradish, do not use silver as the horseradish will immediately tarnish it and taint the taste of food.
The International Horseradish Festival is held annually in Collinsville, IL. That area is part of what is known as the American Bottoms, a Mississippi River Basin carved out by the glaciers in the ice age, leaving soil rich in potash, a vital nutrient on which the horseradish thrives. The Southern Illinois area grows 80% - 85% of the world's horseradish.
Horseradish is easy to grow, easy to prepare, easy to use, easy to store and yummy, yummy, yummy. Try it!
, ,  http://www.botanical.com/botanical/mgmh/h/horrad38.html
 A Modern Herbal by Mrs. M. Grieve
 D. Purves and J. W. Lichtman: Cell Marking with Horseradish Peroxidase, 1985
Photo Credits: Thanks to fhiggins, Tuttifrutti and Weezingreens for use of their photos from Plantfiles. The other photo is the author's.
Creamy Horseradish Dip
2 Tbsp. prepared horseradish
2 Cups Cottage cheese
1 Tbsp. Ketchup
1 Tsp. Pepper
Dash of salt
Mix all ingredients together well in a bowl. Cover and chill in the fridge for 4 hours so flavors will blend. Serve with your favorite crackers.
Ensworth Family Horsey Sauce
1/2 Cup each Plain yogurt and Mayonnaise (don't use low-fat mayonnaise)
6 Tbsp. Fresh grated horseradish
2 Tbsp. Orange juice
Salt and white pepper to taste
1/2 Tsp. Sugar
Thoroughly blend yogurt and mayonnaise. Next, blend in horseradish and orange juice. Season to taste with salt and pepper and sugar. Grate a dash of fresh nutmeg if desired.