Minnesota’s late spring frosts dictate a patient approach to getting arugula seeds in the ground. Knowing the best time to plant arugula in minnesota means watching the soil temperature, not just the calendar.
Arugula thrives in cool weather. Plant it too early, and a hard freeze kills the seedlings. Plant it too late, and the heat makes the leaves bitter and tough. Here is exactly when and how to plant arugula in Minnesota for a long, productive harvest.
Best Time To Plant Arugula In Minnesota
The ideal window for planting arugula in Minnesota is early to mid-April for a spring crop, and again in late August for a fall harvest. The key is to sow seeds as soon as the soil can be worked in spring, typically 2–4 weeks before the last expected frost date.
Minnesota’s last spring frost ranges from early May in the south to late May in the north. Arugula seeds germinate in soil temperatures as low as 40°F (4°C), but they do best between 45°F and 65°F. Once the soil hits 50°F, you are safe to plant.
Spring Planting Window
- Southern Minnesota (Zone 4b–5a): Plant around April 1–15
- Central Minnesota (Zone 4a–4b): Plant around April 10–25
- Northern Minnesota (Zone 3b–4a): Plant around April 20–May 5
If you want an even earlier start, use a cold frame or row cover. These protect young plants from a sudden frost and warm the soil by a few degrees.
Fall Planting Window
Arugula actually tastes sweeter after a light frost. For a fall crop, plant seeds about 6–8 weeks before the first expected fall frost. In Minnesota, that means:
- Southern MN: Plant around August 15–September 1
- Central MN: Plant around August 10–25
- Northern MN: Plant around August 1–15
Fall arugula often produces better than spring arugula because the cooler nights keep the leaves tender and less bitter.
Soil Temperature And Germination
Do not rely solely on the calendar. Use a soil thermometer to check the temperature at 2 inches deep. Arugula seeds will germinate in soil as cold as 40°F, but germination is slow and uneven. At 50°F, seeds sprout in 7–10 days. At 60°F, they sprout in 4–6 days.
If the soil is too wet or too cold, seeds can rot. Wait until the soil is crumbly and not muddy. In Minnesota, that often means mid-April in the south and early May up north.
How To Test Soil Temperature
- Buy a simple soil thermometer from a garden center
- Push it 2 inches into the soil in the morning
- Take the reading three days in a row
- Plant when the average is above 45°F
If you don’t have a thermometer, watch for signs: when dandelions bloom and lilac leaves are the size of a mouse’s ear, the soil is warm enough for arugula.
Succession Planting For Continuous Harvest
One planting of arugula will bolt (go to seed) in about 3–4 weeks once temperatures rise above 75°F. To have a steady supply, plant a new row every 10–14 days from early spring through early fall.
Here is a simple succession schedule for Minnesota:
- First planting: April 10 (south) or April 25 (north)
- Second planting: April 25 (south) or May 10 (north)
- Third planting: May 10 (south) or May 25 (north)
- Fourth planting: August 15 (south) or August 1 (north)
- Fifth planting: September 1 (south) or August 15 (north)
Stop planting spring arugula by mid-June. The summer heat will make it bolt too fast. Focus on fall plantings instead.
Preparing The Soil For Arugula
Arugula is not fussy, but it grows best in loose, well-drained soil with a pH between 6.0 and 7.0. In Minnesota, heavy clay soil is common. Amend it with compost or aged manure to improve drainage and fertility.
Steps To Prepare Your Bed
- Clear the area of weeds and debris
- Loosen the soil to 6–8 inches deep with a garden fork or tiller
- Mix in 1–2 inches of compost
- Rake the surface smooth and level
- Water the bed a day before planting to settle the soil
Do not over-fertilize arugula. Too much nitrogen makes the leaves grow fast but also makes them more prone to bolting and less flavorful. A light application of balanced organic fertilizer (like 5-5-5) is enough.
How To Plant Arugula Seeds
Arugula seeds are tiny. Plant them shallow—only 1/4 to 1/2 inch deep. Space seeds about 1 inch apart in rows that are 10–12 inches apart. If you prefer a more natural look, scatter the seeds thinly over the bed and cover with a fine layer of soil.
Direct Seeding Vs. Transplanting
Arugula does not transplant well. The roots are delicate, and moving seedlings often causes them to bolt early. Always direct sow arugula seeds in the garden. If you must start indoors, use biodegradable pots and transplant when the seedlings have 2 true leaves, being very careful not to disturb the roots.
Watering After Planting
Keep the soil consistently moist until seeds germinate. Use a gentle spray from a hose or watering can to avoid washing the seeds away. After germination, water deeply once or twice a week, depending on rainfall. Arugula needs about 1 inch of water per week.
In Minnesota’s dry spring spells, you may need to water more often. Mulch around the plants with straw or shredded leaves to retain moisture and keep the soil cool.
Thinning And Spacing
Once seedlings are 1–2 inches tall, thin them to 4–6 inches apart. Crowded arugula grows leggy and produces smaller leaves. The thinnings are perfectly edible—add them to salads or sandwiches.
For baby arugula (harvested when leaves are 2–3 inches long), you can skip thinning and just cut the whole patch. For full-sized leaves (4–6 inches), proper spacing is important.
Protecting Arugula From Frost
Arugula can survive light frosts (down to 28°F) without damage. Harder frosts (below 25°F) may kill the leaves, but the plant often recovers from the crown. If a hard freeze is forecast, cover the bed with a row cover or old sheet overnight.
In Minnesota, spring frosts are common even in May. Keep floating row covers handy. They add 4–6°F of protection and can be left on all season to deter flea beetles.
Common Pests And Problems
Arugula in Minnesota faces a few pests, especially flea beetles. These tiny black bugs chew small holes in the leaves, making them look like they were shot with buckshot. They are worst in hot, dry weather.
How To Manage Flea Beetles
- Cover seedlings with floating row cover immediately after planting
- Use diatomaceous earth dusted on the leaves
- Plant arugula in a spot that had no brassicas (cabbage, kale, broccoli) the previous year
- Water regularly to keep plants vigorous
Other problems include bolting (going to seed) in hot weather, and leaf miners that create squiggly tunnels in the leaves. Remove affected leaves promptly to prevent spread.
Harvesting Arugula
You can start harvesting baby arugula as soon as leaves are 2–3 inches long, about 20–25 days after planting. For full-sized leaves, wait until they are 4–6 inches long, about 35–40 days after planting.
Cut-And-Come-Again Method
Use scissors to cut the outer leaves, leaving the inner rosette to keep growing. This method gives you multiple harvests from the same plant. Cut no more than one-third of the plant at a time. Let it regrow for 10–14 days before harvesting again.
If you cut the whole plant at the base (like a head of lettuce), it will not regrow. Only use this method if you want a single large harvest.
Storing Fresh Arugula
Arugula wilts quickly after harvest. To keep it crisp, wash the leaves in cold water, spin them dry in a salad spinner, and store them in a plastic bag with a paper towel. Keep it in the crisper drawer of your fridge. It will stay fresh for 5–7 days.
Do not store arugula near apples or pears—the ethylene gas from these fruits will make the leaves turn yellow and slimy.
Growing Arugula In Containers
If you have limited space or poor soil, grow arugula in containers. Use a pot at least 6 inches deep with drainage holes. Fill with quality potting mix. Sow seeds 1/2 inch deep and 1 inch apart. Thin to 4 inches apart after germination.
Containers dry out faster than garden beds, so check soil moisture daily. Place the pot in a spot that gets 4–6 hours of sun per day. In Minnesota’s hot summer, move the pot to partial shade to delay bolting.
Best Arugula Varieties For Minnesota
Not all arugula varieties handle Minnesota’s climate the same way. Choose varieties that are bolt-resistant and cold-tolerant.
Top Picks
- Sylvetta – Wild arugula, very slow to bolt, peppery flavor
- Astro – Mild flavor, fast growing, good for baby greens
- Wasabi – Extra spicy, bolt-resistant, great for fall
- Rocket – Classic Italian variety, reliable in cool weather
- Apollo – Hybrid, very bolt-resistant, good for spring and fall
For Minnesota’s short spring, Astro and Apollo are the safest bets. For fall, Wasabi and Sylvetta hold up better in cooler temps.
Extending The Season With Cold Frames
If you want arugula even earlier in spring or later in fall, use a cold frame. This simple structure traps heat from the sun and protects plants from frost. You can plant arugula 3–4 weeks earlier in spring and harvest 4–6 weeks later in fall.
How To Use A Cold Frame
- Build or buy a cold frame with a clear lid (glass or polycarbonate)
- Place it over your arugula bed in late March (south) or early April (north)
- Open the lid on sunny days above 50°F to prevent overheating
- Close it at night to trap warmth
- Plant seeds directly in the cold frame soil
With a cold frame, you can harvest arugula from April through November in most of Minnesota.
Common Mistakes To Avoid
Even experienced gardeners make mistakes with arugula. Here are the most common ones in Minnesota:
- Planting too early in wet soil – seeds rot
- Planting too late in spring – plants bolt fast
- Overcrowding – small, leggy leaves
- Underwatering – bitter, tough leaves
- Ignoring flea beetles – leaves get riddled with holes
- Not succession planting – a single harvest then nothing
Avoid these, and you will have arugula all season long.
Frequently Asked Questions
Can I plant arugula in July in Minnesota?
It is not ideal. July heat makes arugula bolt quickly and taste bitter. If you want a summer harvest, plant in a shady spot and water frequently. But you will get better results waiting for the fall planting window in August.
How late can I plant arugula in Minnesota?
You can plant arugula as late as early September in southern Minnesota and mid-August in northern Minnesota. The plants will grow until a hard freeze kills them. A light frost actually improves the flavor.
Should I soak arugula seeds before planting?
No. Arugula seeds are small and do not need soaking. Soaking can cause them to rot in cold soil. Just plant them dry and keep the soil moist.
Does arugula need full sun in Minnesota?
Arugula grows best in full sun (6+ hours per day) in spring and fall. In summer, partial shade (4 hours of sun) helps prevent bolting. In Minnesota’s intense July sun, afternoon shade is beneficial.
Can I grow arugula indoors in Minnesota?
Yes, you can grow arugula indoors under grow lights year-round. Use a shallow container, potting mix, and provide 12–16 hours of light per day. Harvest leaves when they are 2–3 inches long. Indoor arugula is milder than outdoor arugula.
Final Tips For Success
Plant arugula early and often. Watch the soil temperature, not the calendar. Use row covers for frost protection and flea beetle control. Harvest leaves when they are young and tender. And always plant a fall crop—it is often the best arugula of the year.
In Minnesota, the best time to plant arugula in minnesota is a moving target depending on your location and the weather each year. But if you follow the guidelines here, you will have fresh, peppery greens from spring through fall.
Start with a small patch. See what works in your microclimate. Then expand next year. Arugula is one of the easiest greens to grow, and once you taste homegrown leaves, you will never go back to store-bought.
Now go check your soil temperature. The first planting window is closer than you think.