Growing Radishes in Zone 4a
A complete, zone-4a timeline for Radishes — when to start, transplant, and harvest, tuned to this zone's typical frost dates (Minneapolis, MN; Bangor, ME).
Your planting timeline
- Direct sowonce soil warms, around May 17
- Harvestabout 22–35 days from transplant
Best varieties for zone 4a
Spring and fall both work — sow fast round types in early spring, then add a late-summer crop of French Breakfast and a short-season daikon for a frost-sweetened fall harvest.
Growing notes
Even, consistent moisture is the single biggest factor in good radishes. Keep the soil steadily damp — never bone-dry, never waterlogged — so the roots swell quickly and stay mild and crisp. Irregular watering, especially a drought followed by a heavy soaking, causes the roots to split or turn pithy and unpleasantly hot. In dry spring weather that usually means a thorough watering every two to three days; in cool, damp conditions rainfall may be enough. Water at the base in the morning to keep foliage dry, and mulch lightly between rows to hold moisture and even out the soil temperature.
Recommended supplies
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