Those of us who grow food plants know there are some mighty tough, resilient plants in our garden. Once established, rhubarb and asparagus are very tough, tolerating terrible winters and even hot, droughty summers. Another is horseradish.
Horseradish spreads by root fragment and by seeds, so if you grow it, be prepared to confine it, lest it take over your entire garden bed. Plant in loose soil, amended with organic matter. Do not apply manure at the time of planting. If you’re to use manure in your garden, use composted manure in autumn, not in spring, for it can cause root vegetables to fork into myriad slender roots.
You’ll want your horseradish to grow one or two thick roots that can be easily peeled. Plant it by itself, no companions, and keep the area free of weeds. This crop usually doesn’t need fertilizer, but it does need full sun and a fair amount of moisture, perhaps 1 inch per week, like most of the rest of your garden.
You can dig roots any time you need them, but it’s best to dig them when the soil is cool such as in autumn, winter or early spring. The coolth promotes the development of the compound that increases pungency or heat of horseradish. Some folks use a spading fork to dig around the plant, loosening soil so you can use your fingers to find the tap root. That tap root tends to grow laterally rather than straight down, like most tap roots.
Wash off the roots, and put in plastic baggie (and seal it), put it in the refrigerator until you need to use it. Unpeeled horseradish roots reportedly emit no odor. High heat destroys the flavor compounds in horseradish, but air exposure can arouse their mustard oil pungence. If you’re going to grate them, you’re better off doing it outdoors. Mother Earth News author Barbara Pleasant drops grated horseradish root into a jar containing one tablespoon white vinegar, one tablespoon water, and a quarter teaspoon each of sugar and salt. This mix preserves the pungence and flavor. Once grated, you can add to ketchup to create shrimp cocktail sauce, or sour cream for meats or add to creamy mayonnaise or mustard for other condiments.
Horseradish plants will send up white flower stalks in summer that you should remove, lest resulting seeds start new plants where you won’t want them. They’re not usually attractive to destructive insects, but slugs may attack them.
Another fairly tough plant is bulbing fennel, or Florence fennel. If this is what you intend to grow, make sure you have the correct seeds, for the herb fennel produces the flavorful fronds, but no swollen bulb at the base. You can start Florence or Finocchio fennel indoors in darkness, but often the seedlings have a long above-soil “root” that you must bury when you transplant outdoors. You can plant seeds outdoors after last frost, or it will self-seed if soil-protective mulch permits.
It produces its bulb (thickened leaf stems) best in cool weather. Both bulb and fronds are used for flavor (a slight anise or licorice flavor) and for an aid to digestion. Some also call for using the pollen of fennel, and that may be even of wild fennel, or either the herb or the vegetable.
It will tolerate light frosts, but is vulnerable to root rot if overwatered. Sudden temperature changes may spur it to bolt to flower and seed (seeds are useful, too, for flavoring many foods such as those in the Mediterranean area, and for medicinal purposes). Chewing seeds may ease the pain of sore gums, for instance.
Send garden questions to firstname.lastname@example.org or Gardening, The Statesman, P.O. Box 40. Boise, ID 83707.