Gardening: Horseradish


The strong flavors of horseradish tend to create strong feelings: you either love it or you hate it. I love it on a roast beef sandwich or in a shrimp sauce. For most people, horseradish comes in a small bottle that languishes forever on the door of the refrigerator. But, just like tomatoes, fresh homegrown is better than the store-bought kind, so you may wish to grow your own. This is the time of year most people harvest and plant horseradish, though you can do either almost anytime.

Horseradish, along with rhubarb and asparagus, is one of the few perennial vegetables we can grow in New England. Once you have it, you will always have it — even if you decide you don't want it anymore — so think where you want it before planting. Fortunately, a small patch doesn't increase in size very quickly. About the only way to get rid of horseradish (or at least for an organic gardener who eschews herbicides) is to turn the patch into lawn. Even then, new shoots will come up through the lawn decades later.

Once established, the roots go down two feet or more into the soil. Because the roots branch and they are brittle, one can never get all the roots out. Even a scrap of the root will re-sprout, so the plants are there for life. Horseradish is as persistent as it is piquant.

Horseradish is in the cabbage family, but unlike its kissing cousins, it is the root, not the leaves, that you eat. And unlike other crucifers, horseradish is not started by seed, but by planting a cutting. The Johnny's Selected Seeds catalog ( or 877-564-6697), one of very few that offer cuttings, explains that the seeds are not viable. They ship cuttings in April, "after danger of freezing in transit has passed." But you can also get cuttings from a friend who is harvesting now and plant some this fall.

Prepare a horseradish bed by working in some well-rotted manure or compost. That will improve soil texture and keep the soil looser — for ease in future harvesting. Horseradish, which is essentially a weed, doesn't need high levels of nitrogen, phosphorus or potassium.

To prepare a cutting for planting, dig a root from an existing plant and slice off the leaves. Plant the crown (where you cut off the leaves) and a section of root — three to six inches of root is fine. Plant the cuttings a foot or more apart. Water well, and surround with mulch to keep down the weeds. In a year or two you will be ready to harvest. Younger roots are easier to use for sauce than old, woody roots. Horseradish does best in well-drained soil, but really will grow anywhere. It will be most vigorous in full sun, but four hours is plenty.

To harvest, loosen the soil around a plant, either with a garden fork or a drain spade. Drain spades have blades that are about 16 inches long and five inches wide, and are great for digging out deep-rooted things like horseradish. A mature root will challenge even the strongest backs, so you may need to sever the root with your spade to remove it.

Prepare the horseradish for making sauce by hosing off the dirt, then peeling the dark brown skin to reveal its white interior. A potato peeler works just fine for that. The fumes of horseradish are very pungent, so think about working outdoors on a breezy day.

Horseradish root is tough stuff and can defeat your food processor unless you chop it up a bit by hand. Slice a chunk of horseradish lengthways into sections, then chop into pieces about three-quarters of an inch in length before putting in the food processor. To prepare the sauce, grind the chopped roots in the food processor with a little cold water. Pulse the horseradish until it is coarsely chopped.

Grinding the roots releases the volatile oils (isothiocyanates), which give horseradish sauce its heat. Adding vinegar, besides adding flavor and helping to preserve the sauce, controls the level of heat. Add vinegar immediately, and the sauce is moderately hot. Wait three minutes before adding vinegar and the sauce will be spicier. In any case, blend the vinegar with the ground root until the consistency is moist and creamy. Add salt if you are so inclined. Put in a glass jar and store in the fridge.

The nice aspect of horseradish, for gardeners who want it for their kitchen, is that it is essentially labor free. Plant it, and walk away. The outer leaves, which are a bit coarse-looking, will sometimes get brown and scraggly-looking, and slugs will occasionally nibble them, but the plants are trouble-free. They'll be there, just waiting for you to harvest the roots. Now, if someone would just create corn and tomatoes that were so undemanding, everybody would garden.

Read Henry's blogs at His website is He is on vacation and will not be answering-mail this week.


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