Colorado’s unpredictable weather suggests planting calla lilies in late May or early June for the best results. The best time to plant calla lily in Colorado is after the last frost date, when soil temperatures have warmed to at least 60°F. This timing helps your calla lilies avoid cold damage and thrive in the state’s unique climate.
Understanding Colorado’s Climate For Calla Lilies
Colorado’s climate is tricky for tender perennials like calla lilies. You face cold nights even in late spring, and sudden snowstorms are possible. The state’s high altitude means intense sun and rapid temperature swings.
Calla lilies are native to South Africa. They love warmth and hate frost. In Colorado, you must treat them as annuals or dig up the rhizomes each fall.
The growing season in Colorado is short. Most areas have only 100 to 150 frost-free days. This means you need to plan your planting carefully.
Why Timing Matters So Much
Planting too early risks frost damage. The rhizomes can rot in cold, wet soil. Planting too late means less time for blooms before fall frost returns.
Calla lilies need about 90 to 120 days from planting to flowering. If you plant in early June, you should see blooms from mid-August through September.
Late May planting gives you a longer bloom period. But you must watch the weather forecast closely.
Best Time To Plant Calla Lily In Colorado
The ideal window is from late May to mid-June. This varies slightly by your specific location in Colorado.
Denver and the Front Range typically have their last frost around May 10 to May 15. Higher elevations like Colorado Springs or Boulder may see frost into late May.
Mountain towns like Leadville or Breckenridge can have frost even in June. Gardeners there should wait until early June or even mid-June.
Checking Your Local Frost Dates
You can find your area’s average last frost date online. The Colorado State University Extension website has good resources.
Don’t rely solely on calendar dates. Check the 10-day forecast before planting. If night temperatures are predicted to drop below 50°F, wait a bit longer.
Soil temperature is also key. Use a soil thermometer. Insert it 4 inches deep. The soil should be at least 60°F.
What If You Plant Too Early?
If you plant in April or early May, your calla lilies may struggle. Cold soil slows root growth. The rhizomes can rot if the ground stays wet and cold.
Frost can kill the emerging shoots. You might see stunted growth or no blooms at all. Some gardeners lose their entire planting.
If you must plant early, use containers. You can move them indoors if frost threatens. Or cover the soil with black plastic to warm it up.
Preparing Your Garden For Calla Lilies
Good preparation helps your calla lilies grow strong. Start with the right location.
Choosing The Right Spot
Calla lilies need full sun to partial shade. In Colorado’s intense sun, afternoon shade is helpful. Morning sun with afternoon shade works well.
Choose a spot with well-draining soil. Calla lilies don’t like wet feet. Raised beds or slopes are ideal.
Protect your plants from strong winds. Colorado’s gusts can damage tall flower stems. A sheltered spot near a wall or fence is good.
Improving Your Soil
Colorado soil is often clay-heavy or sandy. Both need amendment. Add organic matter like compost or well-rotted manure.
Work the compost into the top 8 to 10 inches of soil. This improves drainage and adds nutrients. Aim for a soil pH between 6.0 and 7.0.
If your soil is very clay, consider planting in containers. Use a high-quality potting mix designed for bulbs.
When To Prepare The Soil
Prepare your soil about two weeks before planting. This gives the amendments time to settle. It also lets the soil warm up faster.
Remove any weeds or rocks. Break up large clumps of soil. Rake the area smooth.
Step-By-Step Planting Guide
Follow these steps for the best results. Timing is everything in Colorado.
- Wait for the right time. Plant after your last frost date and when soil is 60°F.
- Soak the rhizomes. Place them in lukewarm water for 1 to 2 hours before planting. This rehydrates them.
- Dig holes. Make them 4 to 6 inches deep. Space holes 12 to 18 inches apart.
- Place the rhizomes. Put them with the growing tips facing up. The “eyes” should be on top.
- Cover with soil. Fill the holes gently. Don’t pack the soil too tight.
- Water thoroughly. Give them a good soak after planting. This settles the soil.
- Add mulch. Use 2 to 3 inches of organic mulch. This keeps soil cool and moist.
Container Planting Tips
Containers are great for Colorado gardens. You can move them if weather turns cold.
Use pots at least 12 inches wide and deep. Ensure they have drainage holes. Fill with quality potting mix.
Plant one rhizome per 12-inch pot. Or space them 6 inches apart in larger containers.
Place containers in a sunny spot. Water when the top inch of soil feels dry. Containers dry out faster than garden beds.
Caring For Calla Lilies After Planting
Proper care ensures healthy growth and beautiful blooms. Colorado’s climate requires some extra attention.
Watering Needs
Calla lilies like consistent moisture. Water deeply once or twice a week. Adjust based on rainfall and temperature.
In Colorado’s dry air, you may need to water more often. Check the soil regularly. It should feel moist but not soggy.
Use drip irrigation or soaker hoses. This keeps water off the leaves. Wet foliage can lead to fungal diseases.
Fertilizing Schedule
Feed your calla lilies every 4 to 6 weeks during the growing season. Use a balanced fertilizer like 10-10-10.
Apply fertilizer when you first plant. Then again when flower buds appear. Stop fertilizing in late summer.
Too much nitrogen can cause lots of leaves but few flowers. Follow the package directions carefully.
Mulching And Weed Control
Mulch helps retain moisture and keeps soil cool. In Colorado’s heat, this is very important.
Use organic mulch like bark chips or straw. Apply a 2 to 3 inch layer around the plants. Keep mulch away from the stems.
Remove weeds regularly. They compete for water and nutrients. Hand pull weeds to avoid disturbing the shallow roots.
Dealing With Pests And Diseases
Calla lilies are generally pest-free in Colorado. But you may encounter some issues.
Aphids can appear on new growth. Spray them off with water or use insecticidal soap. Slugs and snails may bother plants in damp areas.
Root rot is the biggest risk. It happens in poorly drained soil. Prevent it by planting in well-draining soil and not overwatering.
Powdery mildew can occur in humid conditions. Space plants for good air circulation. Water at the base, not on leaves.
Extending The Bloom Season
You can enjoy calla lily flowers for longer with some simple tricks. Colorado’s short season makes this worthwhile.
Succession Planting
Plant some rhizomes in late May and others in mid-June. This staggers the bloom time. You’ll have flowers from August into October.
Choose early-blooming varieties for the first planting. Late-blooming types work for the second round.
Deadheading Spent Blooms
Remove faded flowers promptly. This encourages the plant to produce more blooms. Cut the stem down to the base.
Leave the foliage in place. The leaves continue to feed the rhizome. This helps next year’s growth.
Using Shade Cloth
In hot weather, calla lilies may stop blooming. Use shade cloth to protect them from intense afternoon sun.
A 30% to 50% shade cloth works well. Install it over a simple frame. Remove it when temperatures cool down.
Overwintering Calla Lilies In Colorado
You cannot leave calla lily rhizomes in the ground over winter in Colorado. The ground freezes too deep.
You have two options: dig them up or treat them as annuals. Most gardeners choose to dig them up.
When To Dig Up Rhizomes
Dig up your calla lilies after the first frost kills the foliage. This is usually in late September or early October.
Don’t wait too long. The ground can freeze quickly in Colorado. Dig them up before the soil freezes hard.
How To Store Rhizomes
Carefully dig up the rhizomes. Shake off excess soil. Cut back the dead leaves to about 2 inches.
Let the rhizomes dry in a warm, airy place for a few days. This prevents rot during storage.
Store them in a box with peat moss or vermiculite. Keep them in a cool, dark place. Temperatures between 45°F and 55°F are ideal.
Check them monthly. Remove any that show signs of rot. Discard mushy or moldy rhizomes.
Replanting In Spring
In late May, take out your stored rhizomes. Inspect them for damage. Soak them in water for an hour before planting.
Plant them following the same steps as before. Your calla lilies will grow again from the same rhizomes.
Common Mistakes To Avoid
Colorado gardeners often make these errors. Avoid them for better results.
- Planting too early. Wait until late May or June. Cold soil kills rhizomes.
- Poor drainage. Calla lilies rot in wet soil. Amend clay soil or use raised beds.
- Overwatering. Too much water causes root rot. Water deeply but less often.
- Ignoring frost. Cover plants if frost is forecast. Use cloth or bring containers inside.
- Not digging up rhizomes. They won’t survive Colorado winters. Dig them up every fall.
Best Calla Lily Varieties For Colorado
Some varieties perform better in Colorado’s climate. Choose these for reliable blooms.
- Heritage – Large white blooms, very hardy
- Flame – Orange-yellow flowers, heat tolerant
- Picasso – Purple with white edges, compact size
- Captain Reno – Red blooms, good for containers
- Black Star – Deep purple, almost black, dramatic
These varieties handle Colorado’s temperature swings well. They also bloom within the short growing season.
Frequently Asked Questions
Can I Plant Calla Lilies In Colorado In April?
No, April is too early. The soil is still cold and frost is likely. Wait until late May or June for the best time to plant calla lily in Colorado.
How Deep Should I Plant Calla Lily Rhizomes In Colorado?
Plant them 4 to 6 inches deep. In sandy soil, plant a bit deeper. In clay soil, plant shallower to avoid rot.
Do Calla Lilies Need Full Sun In Colorado?
They need full sun to partial shade. Morning sun with afternoon shade is ideal in Colorado’s intense light. Too much afternoon sun can scorch the leaves.
How Often Should I Water Calla Lilies In Colorado?
Water deeply once or twice a week. Check the soil moisture regularly. Colorado’s dry air may require more frequent watering, especially in containers.
Can Calla Lilies Survive Winter In Colorado If Mulched?
No, even with heavy mulch, calla lily rhizomes will freeze in Colorado winters. You must dig them up and store them indoors.
Final Tips For Success
Planting calla lilies in Colorado requires careful timing. The best time to plant calla lily in Colorado is late May to mid-June, after frost danger passes.
Prepare your soil well. Choose a sunny spot with good drainage. Water consistently but don’t overdo it.
Dig up rhizomes each fall. Store them properly. Replant them next spring for another season of beautiful blooms.
With these steps, you can enjoy calla lilies even in Colorado’s challenging climate. They add elegance to any garden. Their unique flowers are worth the extra effort.
Start planning now. Check your local frost dates. Get your soil ready. Your calla lilies will thank you with stunning flowers all summer long.