How to Grow Arugula in Canada

Arugula is one of the fastest, most rewarding crops you can grow in a Canadian vegetable garden. It goes from seed to harvest in 21–40 days depending on the season, thrives in cool spring and fall weather, and self-seeds freely if you let it go to flower. This guide covers everything you need to know, from zone-by-zone timing to managing the inevitable summer bolt.

Why Arugula Thrives in Canadian Conditions

Arugula (Eruca vesicaria ssp. sativa) is a cool-season annual that prefers soil temperatures between 10–18°C — exactly the conditions of a Canadian spring and fall. It tolerates light frost down to about -3°C and can extend well into November under row cover in zones 5–6.

The challenge in Canada is summer: arugula bolts (goes to flower and seed) quickly in heat above 25°C. The solution is succession planting in spring, a summer pause, and a fall resow.

Zone-by-Zone Timing

How to Direct Sow Arugula

Arugula is always direct-seeded — transplanting is unnecessary and disruptive to the small taproot.

1. Prepare a fine seedbed — arugula seeds are tiny and germinate best in loose, weed-free soil
2. Sow shallowly — cover with just 0.5 cm of soil
3. Spacing — scatter seeds thinly in 15 cm wide bands, or sow in rows 20–25 cm apart
4. Germination — 5–7 days at 10–15°C; 3–4 days at 18–20°C
5. Thin to 8–10 cm apart when seedlings reach 3–4 cm

Succession Planting for Continuous Harvest

A single sowing of arugula provides 2–3 cuttings over 3–4 weeks before it turns too peppery or bolts. To maintain a continuous supply:

• Sow a new 30 cm row every 10–14 days from first sow date to 6 weeks before expected heat above 25°C
• Resume succession sowing in late July or early August for a fall crop
• In zones 5–6, the fall crop often outlasts the spring crop — cooler nights slow bolting considerably

Use the free planting calculator at mygardenplanner.ca to count backwards from your target harvest dates and generate a succession sowing schedule automatically.

Harvesting Arugula

Baby arugula (35–40 days): Harvest individual leaves when 5–8 cm long. Use scissors or a knife to cut 2–3 cm above soil level, leaving the growing point intact. Plants will regrow 2–3 more times.

Full-size arugula (21–28 days for cut-and-come-again): For stronger peppery flavour, let plants reach 10–12 cm. Cut the whole plant and let it regrow once.

Seed harvest: Let one or two plants bolt completely. Seed pods dry on the plant by late July in zone 5–6. Collect and store for next year's spring sowing.

Managing Bolt and Summer Heat

Arugula bolts when daytime temperatures consistently exceed 25°C. Signs of impending bolt:

• Leaves become narrow, deeply lobed, and intensely peppery
• Central stem elongates
• Flower buds appear at the growing tip

Delay bolt by:

• Providing afternoon shade (plant behind taller crops like tomatoes or beans)
• Consistent watering — moisture stress accelerates bolting
• Growing wild arugula (Diplotaxis tenuifolia) — slower-bolting, more intense flavour, and a true perennial in zone 6+

Pests and Problems

Flea beetles — The biggest pest for arugula in Canada. Tiny holes appear in leaves as if from a pepper grinder. Protect young seedlings with floating row cover immediately after sowing. Once plants are established (6+ weeks), flea beetle damage is cosmetic, not fatal.

Downy mildew — Grey fuzzy patches on leaf undersides in wet conditions. Improve air circulation and avoid overhead watering. Most common in fall crops during cool, wet nights.

Club root — Arugula is a brassica family member. Rotate with non-brassica crops on a 3-year cycle if you have heavy brassica production.

Growing Arugula in Containers

Arugula is excellent in containers — its shallow root system (15 cm depth is sufficient) suits window boxes, balcony planters, and raised beds. Use a container at least 20 cm deep. A 60 cm window box holds two rows of arugula for continuous balcony harvests.

Direct sow in the container, keep consistently moist, and harvest regularly to delay bolting.

Plan Your Arugula Succession on MyGardenPlanner

Arugula's fast turnaround makes it ideal for succession planting — but tracking 5–6 sowing dates across your garden is where a planner earns its keep. Visit mygardenplanner.ca to set up your full arugula succession schedule alongside the rest of your cool-season crops. Check your planting dates for your province to get zone-specific sow windows.