Horseradish is a very hardy perennial. The winter of 2010-2011 was the coldest in many years. I did not insulate my horseradish containers and my plants started to grow just fine in the spring of 2011.
Horseradish is great for containers because it can overrun a conventional bedded garden. Plant horseradish 3 weeks before your last frost date. Use a large, deep container. We use a 20 inch round by 17 inch deep container. You can use even larger ones if you wish. Fill the container with 10 inches of soil in the bottom of the container. Make 2 rows. Place 3 to 3 roots in each row at a 45 degree angle with the small end facing down. Fill with approximately 6 inches of soil with the top of the root just below the surface. The top of the soil should be one inch below the rim of the container.
When the leaves have been killed by frost, the horseradish is ready to harvest. You can loosen the soil with a spade or simply turn the container over and pour the soil out and remove the root. Shake off any dirt, wash and dry the root.
Use the big part of the root for preparation and use the smaller sections for replanting next year’s crop. Use pieces approximately 10 inches long and trim one end at an angle, which will be bottom of the new plant.
The whole root can be grated and stored in a jar filled with white vinegar (this prevents oxidation) but it does not retain it’s flavor too long. It’s better to grate what you need. If you grate the horseradish and wait 2 minutes to cover with vinegar, you will have a milder horseradish. If you wait 6 to 8 minutes, you will have a hotter horseradish. The fumes are strong so make sure you have a window open.
Store any unused horseradish in the refrigerator in a loose plastic bag.