Growing Large Radishes

Botanical Name: Raphanus sativus 

Many radish varieties are sown in early spring or late summer and quickly produce edible roots, often within three weeks. Their size when ripe ranges from that of a marble to that of a golf ball, and if these diminutive table radishes aren’t harvested promptly they can become woody and too spicy.

Heads up, though! Other radishes grow to be quite large indeed, keeping their tasty and tender flesh right through the first frosts of winter. These are daikon radish, Spanish black radish, watermelon radish, German giant radish, and a few other colorful characters.

Often grouped together under the name winter radishes, these radishes require good soil preparation, an abundant and even supply of water throughout their growing season, and some light weeding and thinning so they have enough room to develop fully.

To get large radishes – not only big but healthy – choose a patch of garden that gets direct sunlight for at least six hours a day. Dig the soil deeply and incorporate plenty of composted organic material, like mushroom compost and rotted leaves. After all, the big radish roots willneed room to spread out as well as get plenty of nutrition.

Generally the large radish varieties are planted directly into the ground in late spring or mid-summer, so that they can grow for several months and mature in the cooler months of autumn. Try sowing a portion of the seeds several weeks apart for a longer harvest season.

Meet some of the super-stars of the biggest and best radishes:

  • Spanish black radish, comes in long or round varieties. The skin is nearly black but the flesh is white throughout. A beauty. The round ones are about 2-4 inches across.
  • Watermelon radish, or Red Meat, a very large round radish with unusual coloration –white on the outside with green “shoulders” above the ground, plus a bright red interior.
  • German giant radish, which can be harvest when small but also left for months to get huge… without cracking or becoming bitter.
  • Crimson Giant, quick to mature but super big, and yet sweet and juicy.
  • Large white radish, with several distinctive variations, including a long white Alpine daikon, the plump and early maturing Miyashige daikon, and carrot-shaped Tama hybrid. The April Cross Hybrid daikon grows to several pounds in weight. Japanese Minowase daikon produces reliably and may reach two feet long.
  • Violet de Gournay, an unusual strong-tasting purple radish with its roots in France, is rather stubby and mottled.
  • Formosa Giant Luo Buo, which can grow to nearly three pounds apiece under ideal conditions.

And what to do with all these large radishes? Try grating them for cooking in stir fry or for adding a piquant flavor to steamed fish, or pickling slices of them in a mild vinegar to use as a garnish. Big radishes are nice to eat raw in slices, especially with a dash of salt.