How to grow horseradish...

Horseradish plant

Today we harvested horseradish in the garden. When you harvest you re-plant almost immediately to ensure that you will never run out of horseradish and here in East Africa also because you don't want to loose a rare and valuable plant. The horseradish you harvest will provide you with the material you need for planting. You can use side shoots that you cut off the main roots or you just re-plant those which were too small for harvesting.

A good size crop

Sort the horseradish you have harvested by size. Anything thicker than a pencil or small finger can be used. Cut off the tops and discard. Separate the smaller horseradishes and put aside.

thinner than a pencil - plantlets

Those thinner than a pencil are too small for processing. They are used for re-planting. In case you have no small ones or too few you can also cut thin side shoots of the horseradishes you harvested, and use those for re-planting.

Soil Requirements

Horseradish needs good, deep soil, rich in nutrients. It will exhaust the soil over time and although it can be grown as a perennial crop in the same spot for years is better harvested and transplanted annually. Loosen the soil to 1 meter deep and add lots of compost. Additions of some wood ash and rock phosphate are also advisable. Choose a warm spot in full light. pH requirements for horseradish are between 6.0 - 6.8.

plantlets wrapped in a damp towel

If you can't re-plant the small plantlets immediately keep them in a cold and dark place or wrap them in a damp cloth for a while to avoid that they dry out too much. If you are using side shoots ensure you lay them out in a way that you know which end is the top as they only sprout from the end where they were cut off from the main root.

Growing Advice

For a household 3 - 5 horseradish plants are plenty. For commercial growing around 7500 plantlets per acre are needed.
​Lay the plantlets out in small furrows in such a way that the top of the plantlet is about 3 -5 cm deep in the soil, while the end tip is 6 - 10 cm deep in the soil. They are planted somehow horizontally, but not completely. Cover tem with soil. They should be watered in with diluted liquid fertilizer made from comfrey to encourage fast growth. After about 2 weeks, when the shoots have started growing, the plantlets are 'lifted' 1 cm with a sharp jerk at the crown. This will stop secondary roots from growing and the main root can develop to a satisfying size.
​Ensure good drainage but keep the soil slightly moist at all times. After 12 weeks an application of homemade liquid fertilizer is advisable.   

planted almost horizontally

the top end is 5cm higher than the bottom end

Top planted slightly higher than the tip

Time of Sowing/Transplanting

In East Africa it can generally be grown year round. Best though planted during the small rains. Harvested and re-planted once a year.

Spacing

1 m between rows x 60 cm within the row. In a garden they can be planted closer together as root size is not so important.

Growing period

9 - 12 months

Edible Parts

Roots as a condiment

Pests and Diseases

Flea beetle and spider mite are the only pests I have observed on horseradish in East Africa so far. Flea beetle is a typical drought pest and can be controlled by keeping the soil surface moist. Very typical diseases for horseradish are white rust and leafspot, which can cause considerable damage to the leaves, but have very little influence on the root. Use disease free plantlets to avoid infection with diseases and control outbreaks with copper spray.