Minnesota’s short season means August is the last call for planting quick-growing crops like bush beans and kohlrabi. Finding the Best Vegetables To Plant In August In Minnesota is key to enjoying a late-season harvest before the first frost hits. You can still get a solid yield if you choose the right varieties and act fast.
August planting in Minnesota is all about speed and cold tolerance. The days are warm, but the nights start cooling down. You need vegetables that mature in 30 to 60 days. This guide covers exactly what to plant, when to plant it, and how to protect your crops from early frost.
Best Vegetables To Plant In August In Minnesota
These vegetables are your best bets for a successful late-summer garden. They grow fast, handle cooler nights, and produce before the ground freezes. Let’s break them down by type.
Quick-Growing Leafy Greens
Leafy greens are the stars of August planting. They thrive in cooler weather and can be harvested as baby greens in just a few weeks.
- Lettuce (leaf varieties): Loose-leaf lettuce matures in 30 to 45 days. Plant seeds directly in the soil. Keep them moist for quick germination.
- Spinach: Spinach loves cool weather. It can handle light frosts. Sow seeds ½ inch deep and thin to 3 inches apart.
- Arugula: This peppery green is ready in 20 to 30 days. It grows fast and adds zing to salads. Harvest leaves when they’re 3 to 4 inches long.
- Kale: Kale is tough and frost-tolerant. It actually gets sweeter after a light frost. Plant seeds ½ inch deep and expect harvest in 50 to 60 days.
- Swiss chard: Chard is colorful and productive. It matures in 50 to 60 days. Pick outer leaves to keep the plant growing.
Root Vegetables For Fall Harvest
Root crops are perfect for August planting. They store well and taste better after cool weather.
- Radishes: Radishes are the fastest. Some varieties are ready in 22 to 30 days. Plant seeds ½ inch deep and thin to 1 inch apart.
- Carrots: Choose short or round varieties like ‘Paris Market’ or ‘Nantes’. They mature in 50 to 60 days. Sow seeds ¼ inch deep and keep soil moist.
- Beets: Beets need 45 to 60 days. Plant seeds 1 inch deep and thin to 3 inches apart. Both roots and greens are edible.
- Turnips: Turnips grow fast, maturing in 40 to 50 days. Plant seeds ½ inch deep. Harvest roots when they’re 2 to 3 inches wide.
- Kohlrabi: This odd-looking veggie is crisp and mild. It matures in 45 to 55 days. Plant seeds ½ inch deep and thin to 4 inches apart.
Fast-Maturing Brassicas
Brassicas are cabbage-family crops that handle cool weather well. They’re great for August planting.
- Bush beans: Bush beans are quick and productive. They mature in 50 to 60 days. Plant seeds 1 inch deep and 2 inches apart. Don’t soak seeds before planting.
- Peas (snow or snap): Peas love cool weather. Snow peas mature in 50 to 60 days. Plant seeds 1 inch deep. Provide a trellis for support.
- Broccoli (short-season): Look for varieties like ‘Waltham’ or ‘Green Comet’. They need 50 to 60 days. Start seeds indoors or buy transplants for faster harvest.
- Cauliflower (quick varieties): Try ‘Snow Crown’ or ‘Early White’. They mature in 50 to 60 days. Use row covers to protect from pests.
Herbs And Other Quick Crops
Don’t forget herbs and small vegetables. They add flavor and color to your fall garden.
- Cilantro: Cilantro bolts quickly in heat, but August’s cooler nights slow it down. Harvest leaves in 30 to 40 days.
- Dill: Dill grows fast and attracts beneficial insects. It’s ready in 40 to 50 days. Use fresh or let it go to seed.
- Green onions (scallions): Plant sets or seeds. They’re ready in 40 to 50 days. Pull them when they’re pencil-thick.
- Asian greens (bok choy, tatsoi): These mature in 30 to 45 days. They handle frost well. Plant seeds ½ inch deep.
When To Plant In August In Minnesota
Timing is everything. Minnesota’s first frost usually hits between mid-September and early October, depending on your zone. Check your local frost date. Count backward from that date using the days to maturity on the seed packet. Add 10 to 14 days for fall’s slower growth.
For example, if your first frost is October 1 and you want to plant bush beans that mature in 55 days, plant by August 1. For radishes that mature in 25 days, you can plant as late as September 1.
Planting Windows By Zone
- Zone 3 (northern Minnesota): First frost around September 15. Plant quick crops by August 1.
- Zone 4 (central Minnesota): First frost around September 25. Plant by August 10.
- Zone 5 (southern Minnesota): First frost around October 5. Plant by August 20.
If you’re unsure, plant earlier rather than later. You can always protect plants with row covers if a frost threatens.
How To Plant Your August Garden
August soil is warm, which helps seeds germinate fast. But it can also be dry. Here’s how to set your garden up for success.
Prepare The Soil
- Remove any spent summer crops or weeds.
- Loosen the soil to 6 to 8 inches deep.
- Mix in 1 to 2 inches of compost or well-rotted manure.
- Rake the bed smooth and water it well the day before planting.
Sow Seeds Correctly
- Read the seed packet for depth and spacing.
- Plant seeds slightly deeper than in spring, since the soil is warmer and dries faster.
- Water gently after planting to settle the soil.
- Keep the soil consistently moist until seeds germinate. This might mean watering twice a day in hot weather.
Thin Seedlings
Don’t skip thinning. Crowded plants compete for water and nutrients. Thin to the recommended spacing as soon as seedlings have two true leaves. You can eat the thinnings from greens and radishes.
Caring For Your Late-Season Garden
August gardens need a little extra attention. Heat, pests, and dry soil can stress young plants. Here’s how to keep them healthy.
Watering
Water deeply and consistently. Shallow watering encourages weak roots. Aim for 1 inch of water per week, including rainfall. Use a soaker hose or drip irrigation to keep leaves dry and prevent disease.
Check soil moisture by sticking your finger 2 inches into the soil. If it feels dry, water. In hot spells, you might need to water every day.
Mulching
Mulch keeps soil cool and moist. Spread 2 to 3 inches of straw, grass clippings, or shredded leaves around your plants. This also suppresses weeds.
Fertilizing
Most vegetables need a light feeding 3 to 4 weeks after planting. Use a balanced liquid fertilizer or side-dress with compost. Don’t overdo nitrogen, which encourages leaves over roots.
Pest Control
Late-season pests include aphids, flea beetles, and cabbage worms. Check plants daily. Handpick pests or spray with insecticidal soap. Use row covers to protect brassicas from cabbage moths.
Extending The Season
You can push your harvest weeks past the first frost with a few simple tools. This is crucial for Minnesota’s short growing season.
Row Covers
Floating row covers are lightweight fabric that traps heat. They add 2 to 4 degrees of frost protection. Drape them over hoops or directly on plants. Secure the edges with soil or rocks.
Cold Frames
A cold frame is a box with a glass or plastic top. It captures solar heat and protects plants from frost. You can buy one or build your own from old windows. Place it over your garden bed.
Cloches
Cloches are individual plant covers. Use plastic bottles with the bottom cut off, or buy glass cloches. They work well for small plants like lettuce or radishes.
Mulch For Root Crops
Heavy mulch protects root vegetables from freezing. After the first frost, cover carrots and beets with 12 inches of straw. You can harvest them all winter if the ground doesn’t freeze solid.
Common Mistakes To Avoid
Even experienced gardeners make mistakes in August. Here are the biggest ones to watch out for.
- Planting too late: Check your frost date and count backward. Don’t guess.
- Ignoring soil moisture: August heat dries soil fast. Seeds won’t germinate in dry soil.
- Skipping thinning: Crowded plants produce tiny vegetables. Thin ruthlessly.
- Forgetting to harden off transplants: If you buy transplants, acclimate them slowly over a week.
- Using too much nitrogen: This leads to lush leaves but small roots. Use a balanced fertilizer.
- Not protecting from pests: Flea beetles and aphids love tender new growth. Use row covers early.
Harvesting Tips For Late Crops
Harvest at the right time for the best flavor. Most vegetables taste better after a light frost, but don’t wait too long.
- Leafy greens: Harvest outer leaves when they’re 4 to 6 inches tall. Leave the inner leaves to grow.
- Root vegetables: Pull radishes when they’re 1 inch wide. Carrots are ready when they’re ½ inch wide at the top. Beets are best at 2 to 3 inches.
- Brassicas: Harvest broccoli heads when they’re tight and dark green. Pick cauliflower when the curd is smooth and white.
- Beans and peas: Pick beans when pods are slender and snap easily. Harvest snow peas when pods are flat. Snap peas when pods are plump.
Store root vegetables in a cool, dark place. Greens keep in the refrigerator for a week. Wash them just before eating.
Frequently Asked Questions
Can I plant tomatoes in August in Minnesota?
It’s risky. Tomatoes need 60 to 80 days to mature. Only try if you have a protected spot and a short-season variety. Use row covers or a cold frame.
What vegetables can I plant in late August in Minnesota?
Focus on ultra-fast crops like radishes, arugula, lettuce, and spinach. These mature in 20 to 30 days. You can also plant kohlrabi and turnips if you have 45 days before frost.
Should I use seeds or transplants for August planting?
Seeds are cheaper and work well for most crops. Use transplants for broccoli and cauliflower to save time. Look for healthy, stocky plants at garden centers.
How do I protect my August garden from early frost?
Use row covers, cloches, or cold frames. Water the soil well before a frost, as wet soil holds heat. Cover plants in the evening and remove covers in the morning.
Can I plant carrots in August in Minnesota?
Yes, but choose short-season varieties like ‘Nantes’ or ‘Paris Market’. Plant by August 1 in northern zones and by August 15 in southern zones. Keep soil moist for good germination.
Final Thoughts On August Planting
August planting in Minnesota is a smart way to extend your harvest. You get fresh vegetables well into fall, sometimes even into November. The key is choosing the right crops and protecting them from frost.
Start with leafy greens, root vegetables, and quick brassicas. Prepare your soil well, water consistently, and use season extenders. You’ll be amazed at what you can grow in the last weeks of summer.
Don’t be afraid to experiment. Try a new variety or a different planting method. Every year is a little different, and you’ll learn what works best in your garden. Happy planting.