The “spicy” flavor radishes are known for comes predominantly from their skin. This is due to defense chemicals in the skin, called Allyl isothiocyanates, for warding off herbivores. The same compounds are what make mustard and horseradish spicy.
Hard to compete with horseradish
January 10th 2025Fun fact! Horseradish can be difficult to eradicate once it’s established. This is because the smallest piece of root can grow a new plant. Additionally, the plant spreads by underground shoots that out-compete most other plants which means horseradish can become invasive if not maintained.