Minnesota’s short summer window makes late May the best time to plant canna lilies. Knowing the best time to plant canna lily in minnesota is crucial for getting these tropical beauties to bloom before the first frost hits in early autumn. If you plant too early, a late frost can kill the rhizomes; too late, and you might miss the flowers entirely.
Canna lilies aren’t true lilies, but they bring a bold, tropical look to any Minnesota garden. They thrive on heat and consistent moisture, which our humid summers can provide. The key is timing your planting so the soil is warm enough for them to sprout quickly.
This guide walks you through the exact timing, step-by-step planting, and care tips tailored for Minnesota’s unique climate. You’ll get practical advice to ensure your cannas grow tall and bloom profusely.
Best Time To Plant Canna Lily In Minnesota
Late May to early June is the sweet spot for planting canna lilies in Minnesota. The soil temperature should be consistently above 60°F (15°C) at a depth of 4 inches. You can check this with a simple soil thermometer.
Waiting until after the last frost date is non-negotiable. In southern Minnesota, that’s usually around May 15-20. In northern areas, it can be as late as June 1. Always check your local frost dates before putting rhizomes in the ground.
Planting in late May gives cannas about 90-100 days of warm weather. That’s enough time for most varieties to grow 3-5 feet tall and produce vibrant flowers. If you plant in early June, you’ll still get blooms, but they might be shorter and less abundant.
Why Soil Temperature Matters
Canna rhizomes are sensitive to cold, wet soil. If you plant them when the ground is still cool, they can rot before they even start growing. Warm soil encourages fast root development and strong shoots.
You can warm the soil faster by covering the planting area with black plastic for a week before planting. This simple trick can raise soil temperature by 5-10 degrees, giving you a head start.
If you’re impatient, you can start cannas indoors in pots about 4-6 weeks before the last frost. This gives them a 6-8 week head start. Then transplant them outside after the danger of frost has passed.
Preparing Your Canna Rhizomes For Planting
Before you plant, inspect your canna rhizomes. They should be firm and plump, not soft or mushy. If you see any rotten spots, cut them off with a clean knife and dust the cut with sulfur powder to prevent infection.
Soak the rhizomes in lukewarm water for 2-4 hours before planting. This rehydrates them and helps them wake up from storage. Don’t soak longer than 6 hours, or they might rot.
If you bought rhizomes from a store, they might be dry. That’s normal. Just soak them and they’ll perk up. If they’re already sprouting, handle them carefully so you don’t break the tender shoots.
Choosing The Right Location
Cannas need full sun to bloom their best. That means at least 6-8 hours of direct sunlight daily. In Minnesota, a south-facing spot near a wall or fence can provide extra warmth and protection from wind.
The soil should be rich, well-draining, and slightly acidic (pH 6.0-6.5). If your soil is heavy clay, amend it with compost or aged manure. Cannas are heavy feeders and need plenty of organic matter to thrive.
If you have a wet spot in your garden, cannas can handle it better than most plants. They actually like consistent moisture, but not standing water. Raised beds can help with drainage if your soil is too heavy.
Step-By-Step Planting Guide
Follow these steps for successful canna planting in Minnesota:
- Wait until late May or when soil temperature reaches 60°F.
- Prepare the bed by loosening soil to 12 inches deep.
- Mix in 2-3 inches of compost or well-rotted manure.
- Dig holes 4-6 inches deep and 12-18 inches apart.
- Place the rhizome horizontally with the eyes (buds) facing up.
- Cover with 2-3 inches of soil initially, not the full depth.
- Water thoroughly after planting to settle the soil.
- As shoots emerge, gradually fill in the rest of the soil.
Planting shallowly at first helps the soil warm up around the rhizome. As the shoots grow, you add more soil to support the stems. This technique works well in cooler climates like Minnesota.
If you’re planting in containers, use a large pot (at least 14 inches wide) with drainage holes. Fill with high-quality potting mix and plant the rhizome 4 inches deep. Containers warm up faster than ground soil, so you can plant a week earlier.
Spacing And Depth Tips
Dwarf canna varieties need 12-18 inches between plants. Tall varieties (5-6 feet) need 18-24 inches. Crowding them reduces air flow and can lead to fungal diseases, especially in humid Minnesota summers.
Plant the rhizome at a slight angle, not perfectly flat. This helps water drain away from the eyes and reduces rot risk. The eyes should be no more than 2 inches below the soil surface initially.
If you’re planting multiple rows, stagger them like a checkerboard. This gives each plant more space to spread and makes the bed look fuller. It also helps with air circulation.
Caring For Cannas After Planting
Water your cannas deeply once a week if there’s no rain. They need about 1-2 inches of water per week. In hot, dry spells, water twice a week. Keep the soil consistently moist but not waterlogged.
Fertilize every 2-3 weeks with a balanced fertilizer like 10-10-10. Cannas are heavy feeders and need regular nutrients to produce big leaves and flowers. Stop fertilizing in late August to let the plants prepare for dormancy.
Mulch around the plants with 2-3 inches of straw or shredded bark. This keeps the soil cool, retains moisture, and suppresses weeds. In Minnesota’s variable weather, mulch is a lifesaver.
Dealing With Pests And Diseases
Cannas are generally tough, but they can get pests. Japanese beetles love canna leaves. Hand-pick them in the morning or use neem oil spray. Slugs and snails can also be a problem in wet weather.
Leaf spot and rust can appear in humid conditions. Space plants properly and water at the base, not on the leaves. If you see spots, remove affected leaves and dispose of them in the trash, not compost.
If you notice yellowing leaves, it might be a nitrogen deficiency. Give them a dose of fish emulsion or a balanced fertilizer. If leaves are brown and crispy, they’re getting too much sun or not enough water.
Extending The Growing Season
Minnesota’s first frost usually comes in late September or early October. To get the most from your cannas, you can protect them from early cold snaps. Cover them with a frost blanket or old sheet if frost is forecast.
If you planted late and want to save the flowers, you can dig up the rhizomes before the first hard freeze. Cut the stems to 6 inches, dig carefully, and let the rhizomes dry for a day before storing.
Store rhizomes in a cool, dark place like a basement or garage. Keep them in peat moss or vermiculite at 45-50°F. Check monthly for rot or drying out. They’ll be ready to plant again next May.
Overwintering Cannas Indoors
In Minnesota, cannas are not hardy and must be overwintered indoors. Dig them up after the first frost kills the foliage but before the ground freezes. Shake off excess soil and let them dry for a few days.
Cut the stems to 2-3 inches above the rhizome. Store them in a cardboard box with peat moss or sawdust. Don’t let them touch each other to prevent rot. Keep the box in a cool, dark place that stays above freezing.
If you have a heated garage or basement, that’s ideal. Avoid storing them near furnaces or heat vents, as they can dry out. Check them every month and mist lightly if they seem shriveled.
Common Mistakes To Avoid
Planting too early is the biggest mistake. Even if the air feels warm, the soil might still be cold. Always check soil temperature before planting. A late frost in mid-May can kill tender shoots.
Planting too deep is another common error. Cannas need shallow planting to warm up quickly. If you bury them 6 inches deep, they’ll take forever to sprout and might rot. Start with 2-3 inches of cover.
Overwatering right after planting can cause rot. Water once to settle the soil, then wait until you see shoots before watering again. The rhizome has enough stored energy to start growing without constant moisture.
Neglecting to fertilize is a missed opportunity. Cannas are hungry plants. Without regular feeding, they’ll grow small leaves and few flowers. Use a slow-release fertilizer at planting and liquid feed every few weeks.
What If You Miss The Ideal Window?
If you miss late May, don’t worry. You can still plant in early June and get good results. The plants might be shorter and bloom later, but they’ll still look great. Just water and fertilize consistently.
If it’s already July, consider buying pre-started cannas from a nursery. These are already growing in pots and will bloom faster than starting from rhizomes. Plant them immediately and keep them well-watered.
For August planting, it’s risky but possible. You might only get foliage and no flowers before frost. But the rhizomes will store energy for next year if you overwinter them properly.
Frequently Asked Questions
When is the best time to plant canna lily in Minnesota?
The best time is late May to early June, after the last frost and when soil temperature is above 60°F. This gives them enough warm weather to bloom before fall.
Can I plant canna lilies in July in Minnesota?
Yes, but they may not bloom before the first frost. Choose fast-growing varieties and plant them in a warm, sunny spot. Water and fertilize well to encourage quick growth.
How deep should I plant canna rhizomes?
Plant them 4-6 inches deep, but start with only 2-3 inches of soil cover. As shoots emerge, gradually add more soil to support the stems. This helps the rhizome warm up faster.
Do canna lilies need full sun in Minnesota?
Yes, they need at least 6-8 hours of direct sun daily. Full sun is essential for blooming. In partial shade, they’ll grow leaves but few flowers.
How do I overwinter canna lilies in Minnesota?
Dig up rhizomes after the first frost, let them dry, and store them in a cool, dark place (45-50°F) in peat moss or vermiculite. Check monthly for rot and replant next spring.
Final Thoughts On Planting Cannas In Minnesota
Planting canna lilies at the right time makes all the difference. Late May to early June is your window for success. With warm soil, full sun, and regular care, these tropical plants will transform your Minnesota garden into a lush paradise.
Don’t be afraid to experiment with different varieties. Some are more cold-tolerant and bloom faster. ‘Pretoria’ and ‘Tropicanna’ are popular choices that perform well in our climate. They add height, color, and texture that no other plant can match.
Remember to start small if you’re new to cannas. A few plants in a container or a small bed can give you a taste of their beauty. Once you see how easy they are, you’ll want more next year.
With proper timing and care, your cannas will thrive from June through September. They’ll be the talk of the neighborhood and a highlight of your summer garden. Enjoy the process and the stunning results.