Wisconsin gardeners must wait until the soil warms sufficiently in late spring before setting out canna lily rhizomes. Finding the best time to plant canna lily in wisconsin depends on your local frost dates and soil temperature. This guide gives you the exact timing and steps for success.
Canna lilies are tropical plants that thrive in heat. In Wisconsin’s short growing season, timing is everything. Plant too early and the rhizomes rot. Plant too late and you miss the summer bloom.
Best Time To Plant Canna Lily In Wisconsin
The best time to plant canna lily in Wisconsin is after the last spring frost, when soil temperatures reach at least 60°F (15°C) at a depth of 4 inches. This usually falls between mid-May and early June, depending on your region.
Check your local frost dates. In southern Wisconsin (Zones 5a-5b), the last frost typically occurs around May 10-15. In northern Wisconsin (Zones 4a-4b), wait until May 25-June 5. Use a soil thermometer to confirm warmth.
Why Soil Temperature Matters
Canna rhizomes are sensitive to cold. Soil below 55°F stops root growth and invites fungal rot. Warm soil encourages fast sprouting and strong roots. If you plant too early, the rhizomes may sit dormant and decay.
Measure soil temperature in the morning. Insert the thermometer 4 inches deep in the planting bed. Wait for three consecutive days above 60°F before planting.
Regional Timing For Wisconsin
- Southern Wisconsin (Milwaukee, Madison, Kenosha): Plant May 10-20. Soil warms faster here.
- Central Wisconsin (Wausau, Stevens Point, Green Bay): Plant May 20-30. Watch for late frosts.
- Northern Wisconsin (Eau Claire, Superior, Rhinelander): Plant May 30-June 10. Use black plastic to warm soil faster.
Preparing Your Canna Rhizomes For Planting
Start your cannas indoors 4-6 weeks before the planting date. This gives them a head start in Wisconsin’s short summer. Use pots with drainage holes and quality potting soil.
Indoor Starting Steps
- Fill 6-inch pots with moist potting mix.
- Place one rhizome per pot, horizontally, with the eye (growth bud) facing up.
- Cover with 1-2 inches of soil. Water lightly.
- Keep pots in a warm spot (70-75°F) with bright, indirect light.
- Water only when the top inch of soil feels dry. Overwatering causes rot.
- After 2-3 weeks, sprouts appear. Move to a sunny window or under grow lights.
- Harden off plants 7-10 days before outdoor planting. Set pots outside for a few hours each day, gradually increasing time.
Direct Planting Outdoors
If you skip indoor starting, plant rhizomes directly in the garden after the soil warms. Soak rhizomes in lukewarm water for 2 hours before planting to rehydrate them. Dig holes 4-5 inches deep and space rhizomes 12-18 inches apart.
Place each rhizome with the eye facing upward. Cover with soil and water well. Mark the spot with a stake so you don’t forget where they are.
Choosing The Right Location
Canna lilies need full sun—at least 6-8 hours of direct sunlight daily. In Wisconsin, less sun means fewer blooms and weak stems. Pick a spot protected from strong winds, which can shred the large leaves.
Soil Requirements
Cannas prefer rich, well-draining soil with a pH between 6.0 and 6.5. Amend heavy clay soil with compost or aged manure to improve drainage. Raised beds work well in wet areas.
Test your soil pH with a home kit. If it’s too acidic, add lime. If too alkaline, add sulfur. Mix in 2-3 inches of organic matter before planting.
Caring For Cannas After Planting
Water cannas deeply once a week if rainfall is less than 1 inch. During hot spells, water twice a week. Keep the soil consistently moist but not waterlogged.
Fertilizing Schedule
- At planting: Mix a slow-release 10-10-10 fertilizer into the soil.
- After 4 weeks: Apply a balanced liquid fertilizer every 2-3 weeks.
- Mid-summer: Switch to a high-phosphorus fertilizer (like 5-10-5) to boost blooms.
- Stop feeding: By late August to let plants prepare for dormancy.
Mulching And Weed Control
Apply 2-3 inches of organic mulch (straw, shredded bark, or grass clippings) around the plants. Mulch keeps soil cool, retains moisture, and suppresses weeds. Keep mulch away from the stems to prevent rot.
Pull weeds by hand when small. Avoid deep cultivation that can damage shallow roots.
Common Problems In Wisconsin Gardens
Wisconsin’s climate brings specific challenges. Here’s what to watch for.
Frost Damage
Late spring frosts can kill canna foliage. Cover plants with frost cloth or old sheets if a freeze is forecast. Remove covers in the morning. If frost hits, cut back damaged leaves; new growth may emerge.
Slugs And Snails
These pests love canna leaves in cool, wet weather. Handpick at night or use iron phosphate bait. Diatomaceous earth around plants also works.
Japanese Beetles
These beetles skeletonize leaves in July and August. Knock them into a bucket of soapy water. Neem oil sprays can deter them. Avoid traps, which attract more beetles.
Root Rot
Overwatering or poor drainage causes rhizomes to rot. Symptoms include yellowing leaves and mushy stems. Dig up affected rhizomes, cut away rotted parts, and replant in drier soil.
Extending The Bloom Season
Cannas bloom from mid-summer until the first fall frost. In Wisconsin, that’s usually September to October. To maximize blooms, deadhead spent flowers regularly. Cut the flower stalk back to the main stem after blooming.
Succession Planting
Plant a few rhizomes every 2 weeks from mid-May to early June. This staggers bloom times and gives you flowers longer. Use early, mid, and late-blooming varieties for continuous color.
Overwintering Canna Lilies In Wisconsin
Canna lilies are not winter-hardy in Wisconsin. You must dig up rhizomes before the first hard frost. Wait until after the first light frost kills the foliage but before the ground freezes.
Digging And Storing Steps
- Cut back stems to 4-6 inches above the ground.
- Carefully dig around the rhizome clump with a garden fork. Avoid cutting the rhizomes.
- Shake off excess soil. Rinse with water if needed, then let dry in a shaded, airy spot for 1-2 days.
- Remove any rotten or damaged parts with a clean knife.
- Place rhizomes in a box or crate filled with dry peat moss, vermiculite, or wood shavings. Don’t let them touch each other.
- Store in a cool, dark place at 40-50°F. A basement or garage works well.
- Check monthly for shriveling or rot. Mist lightly if too dry; remove rotting rhizomes.
Alternative: Container Overwintering
If you grow cannas in pots, move the entire container indoors before frost. Cut back foliage and stop watering. Store the pot in a cool, dark place. In spring, repot with fresh soil and resume watering.
Best Canna Varieties For Wisconsin
Choose varieties that mature quickly and tolerate cooler nights. Here are top picks.
- ‘Tropicanna’: Striking striped leaves and orange flowers. Grows 4-5 feet tall.
- ‘Pretoria’ (Bengal Tiger): Yellow-green striped leaves with orange blooms. Reaches 4-6 feet.
- ‘Wyoming’: Bronze leaves and bright orange flowers. Compact at 3-4 feet.
- ‘Red King Humbert’: Deep red flowers on 5-foot stalks. Very reliable.
- ‘Cleopatra’: Unique red and yellow spotted blooms. Grows 3-4 feet.
Frequently Asked Questions
Can I Plant Canna Lilies In Wisconsin In July?
Yes, but you’ll get a shorter bloom period. Plant by early July at the latest. Use started plants from a nursery for faster results.
How Late Can I Plant Canna Lilies In Wisconsin?
Plant no later than June 15 for direct rhizomes. For potted starts, you can plant until early July. Later planting risks frost damage before flowering.
Do Canna Lilies Need Full Sun In Wisconsin?
Yes. Full sun (6+ hours daily) is essential for strong growth and abundant blooms. Partial shade results in leggy plants and fewer flowers.
Should I Soak Canna Rhizomes Before Planting?
Soaking for 2-4 hours in lukewarm water helps rehydrate stored rhizomes. Don’t soak longer than 6 hours to avoid rot.
Can I Leave Canna Lilies In The Ground Over Winter In Wisconsin?
No. Wisconsin winters are too cold. Rhizomes will freeze and die. Always dig them up and store indoors.
Final Tips For Wisconsin Gardeners
Start your cannas indoors for a head start. Use a soil thermometer to avoid planting too early. Water consistently but don’t overwater. Watch for pests like slugs and Japanese beetles.
Dig up rhizomes before the first hard freeze. Store them properly and check monthly. With the right timing and care, your canna lilies will reward you with tropical beauty all summer.
Remember: the best time to plant canna lily in wisconsin is when the soil is warm and the frost risk has passed. Plan ahead, prepare your site, and enjoy the show.