Radishes are the first vegetable that many kids grow, since most “summer” varieties go from seed sowing to harvest in about three weeks, a case of almost instant gratification. Summer radishes are “short-day” crops, and they’ll bolt if daylengths exceed 15 hours. Summer types are also sensitive to heat, but once daytime highs fall below 27°C, radishes are ready to return.
Sow summer radish seed in mid- to late summer every 10 days until about 20 days before your region’s first expected frost date. When the roots are about 2 centimetres in diameter, the entire crop should be harvested (radishes left in the ground too long become corky and hot).
“Winter” or Asian radishes (“daikon”) are more tolerant of long daylengths and midsummer heat. Although they stay in the ground twice as long as red-skinned types, these mild white roots are just as easy to grow. Sow seed at 10 to 14 day intervals from midsummer until about 50 days before your area’s first expected frost date.
Quick tip: To avoid root maggot, don’t plant radishes where you have recently grown cabbage.
"Summer" short-day radishes for late summer planting (20 to 30 days)
"Winter" radishes for midsummer planting (50 to 65 days)
- 'Minowase Summer Cross No. 3'
- 'White Gem'