When to Plant Radishes in Canada 2026 — Spring & Fall Guide by Zone

Radishes are among the fastest crops a Canadian gardener can grow — a spring variety goes from seed to table in 25–30 days. That makes them ideal for impatient gardeners, gap-fillers between slower crops, and anyone who wants two distinct harvests from a short growing season.

The catch: radishes bolt (go to seed) quickly in summer heat. Get the timing right and you'll harvest crisp, peppery roots through spring and fall. Miss the window and you'll get woody, hollow roots and a patch of yellow flowers.

When to Plant Radishes in Spring (Zone by Zone)

Direct-seed radishes as soon as the soil can be worked in spring. They germinate in soil as cold as 5°C and prefer cool temperatures for root development. Unlike tomatoes or peppers, radishes require no warm soil or indoor starting.

Radishes can be seeded 4–6 weeks before your last spring frost date. Find your frost dates at mygardenplanner.ca/frost-dates-canada.

When to Plant Radishes in Fall

Fall radishes often outperform spring crops: nights are cooler, flavour develops more sweetness, and flea beetle pressure drops significantly as temperatures fall. Both quick spring types and large winter radishes like daikon work well as fall crops.

Count back from your first fall frost date:

• Spring types (25–30 days): sow 4–5 weeks before first fall frost
• Winter types — daikon, Black Spanish (55–70 days): sow 70 days before first fall frost

Why Radishes Fail in Summer

Planting radishes in June or July in zones 3–6 almost always fails:

• Bolting — radishes switch to flowering mode in long days and temperatures above 20°C; roots become woody and inedible within days of forming
• Hollow roots — inconsistent summer moisture causes split, pithy interiors
• Flea beetles — these tiny pests riddle brassica leaves with shot holes and stress young plants severely in hot weather

The fix is simple: stick to the cool-season windows above. If you want a fast crop in midsummer, bush beans are a better fit — they thrive in heat and mature in 50–60 days.

Best Radish Varieties for Canadian Gardens

Spring Radishes (25–35 Days)

Fall / Winter Radishes (50–70 Days)

Planting and Growing Tips

• Sowing depth: ½ inch deep, ¼ inch apart; thin to 2-inch spacing when seedlings reach 2 cm tall
• Row spacing: 6 inches between rows
• Watering: Consistent moisture is critical — drought followed by heavy rain splits roots
• Fertilizing: Low-nitrogen approach works best; too much nitrogen drives leafy tops at the expense of root development
• Succession planting: Sow a short row every 7–10 days through the spring window for a continuous harvest rather than one large glut

Companion Planting

Radishes earn their place beyond the salad bowl:

• Near cucumbers and squash — radishes deter cucumber beetles and vine borers
• Interplanted with carrots — fast-germinating radishes mark the slow-germinating carrot row and loosen soil; harvest radishes before they crowd the carrots out
• As a brassica trap crop — plant a row of radishes near your cabbage or kale to draw flea beetles away from your main crop

Plan Radishes Alongside Your Full Garden

Radishes are ideal succession crops — they mature fast enough to fit in gaps between larger plantings. The free planting calculator at mygardenplanner.ca gives you zone-specific sow dates for radishes and all your other vegetables.

Managing a bigger garden or a market plot? The Home Gardener plan ($5/mo) gives you a full season planner with succession scheduling and bed management across all your crops — so your quick-turnover radish rows integrate cleanly with your season plan.