With their trumpet-shaped blooms and lush foliage, calla lilies are a showstopping addition to gardens and flower arrangements. To enjoy their beauty year after year, proper planting techniques for calla lily bulbs are key. This guide covers everything you need to successfully plant calla lily bulbs and keep them thriving.

Understanding Calla Lily Bulbs

Calla lily bulbs consist of a rounded basal plate from which the roots and shoots emerge. Varieties come in white, pink, yellow, purple, and bi-color blooms. Dwarf calla lilies reach 12-18 inches tall, while standard-sized varieties can grow 24-48 inches tall on stems rising above arrow-shaped leaves.

Look for plump, blemish-free bulbs. Avoid any mold, rot, or desiccation damage. Bulb size depends on the variety, but standard callas are often 2-3 inches in diameter. Larger 7/8 size bulbs are established quicker than smaller bulbs.

Selecting a Planting Site

Calla lilies flourish in moist but well-drained soil. Choose a site that gets at least 6 hours of sun per day with some afternoon shade in hotter climates. Morning sun helps dry excess moisture from leaves and prevents disease.

Soil pH between 6.0-7.5 is ideal, enriched with compost or organic matter to retain some moisture. However, soggy sites lead to bulb rot and should be avoided or amended with sand or perlite to improve drainage.

Preparing for Planting

Plant calla lily bulbs in late spring after the last frost date. Bulbs can be stored in a cool place over winter after the growing season ends.

Before planting, loosen and amend the soil if needed. Mix in compost, peat moss or other organic matter to improve moisture retention and nutrition.

Soak bulbs in lukewarm water for 1-2 hours before planting. This rehydrates them from storage and primes them for rooting. Gently remove any loose outer skin or scales on the bulbs.

Planting Process

Dig holes or trenches for planting based on bulb spacing recommendations. Place bulbs 4-6 inches deep and 8-12 inches apart to allow for mature growth.

Set each bulb with the flat basal plate side down. Planting right-side up is critical for proper orientation and growth. Backfill soil and pack gently but firmly around bulbs.

Water newly planted bulbs well to saturate the soil. Allow the soil to dry slightly between waterings. Add 2-3 inches of mulch around planted bulbs to retain moisture.

Aftercare and Maintenance

Keep soil moist but not saturated while bulbs establish a root system and grow foliage, about 4-6 weeks after planting. Water 1-2 times per week if rain is lacking.

Once plants are established, water when the top few inches of soil become dry. Give plants a monthly feeding with balanced soluble fertilizer during the growing season.

Remove faded flowers and leaf tips regularly to keep plants looking tidy. Mulch annually to conserve moisture and insulate roots from temperature extremes.

Potential Challenges and Troubleshooting

Pests: Slugs and snails can eat leaves and flowers. Use barriers and traps to protect plants.

Diseases: Blight, root rot, and viruses may occur if conditions are too wet. Improve drainage and airflow.

Environmental issues: Extreme heat or drought causes foliage to fade and brown. Provide ample water and some shade.

Poor growth: Insufficient nutrients, overcrowding, or improper planting depth can inhibit plants. Fertilize properly, space bulbs well, and plant at the correct depth.

No flowers: Exposure to too much sun can prevent flowering. Give plants some shade, especially in hot climates.

Propagation and Division  

Mature calla lily clumps can be divided every 2-3 years. Carefully dig up bulbs in early spring and use a sterilized knife to separate and replant individual propagules with shoots and roots intact.

Small newly planted bulbs may not bloom the first year. But propagation from mature plants yields mature bulbs that should provide flowers the following growing season after dividing.

What month do you plant calla lily bulbs?

The ideal time to plant calla lily bulbs is in late spring after the threat of frost has passed. Some good target months include:

- April in warmer climates like USDA Zones 9-11

- May in cooler areas like Zones 4-8

Bulbs can be successfully planted through early summer as long as the soil has thoroughly warmed. Prepare soil and site ahead of time so bulbs can establish roots before the peak of summer heat.

Planting in the fall is not recommended. Bulbs need time to root and sprout leaves before winter dormancy. Plant only in spring or early summer to allow enough growing time before frost returns.

How deep should calla lily bulbs be planted?

Proper planting depth is key for calla lily bulbs to sprout and grow successfully. Recommended planting depths are:

- 4-6 inches deep for large bulbs

- 3-4 inches deep for small bulbs

Measure the depth from the top of the bulb to the soil surface. Setting bulbs too shallow leads to inadequate anchoring as plants grow taller. Burying too deep prevents sprouting due to lack of warmth and light.

Aim for the depth recommended based on bulb size. Loosening the soil and amending it with compost or peat moss prior to planting makes achieving the ideal depth easier.

Do calla lilies grow better in pots or in the ground?

Calla lilies can grow well in both garden beds and containers. In-ground planting allows bulbs to spread naturally. But potted callas provide mobility and good drainage control.

For the best growth:

- In beds, amend soil to improve drainage and nourishment

- In pots, use soilless potting mix and fertilize regularly

- Ensure adequate water and light either way

- Bring potted plants indoors before the first frost

With proper care, calla lilies can thrive and flower abundantly when grown in-ground or containerized. Choose the option that best fits your environment and gardening preferences.

Which side is up on a calla lily bulb?

The bottom or basal plate side of the bulb should be facing down when planting calla lilies. This side is flattened or slightly indented compared to the rounded top of the bulb.

Setting bulbs right-side up properly orients the emerging roots downward and leaves upward. It also ensures the sprouts emerge facing skyward for optimal access to light and warmth needed to grow.

Check for a pointed shoot emerging from the top of the bulb. This indicates the upward-facing side. If in doubt, plant on its side to allow the shoot to orient itself upward as it emerges.

Do calla lilies need full sun or shade?

Calla lilies grow best with about 6 hours of direct sunlight daily. More sun causes foliage burn, while too much shade leads to sparse blooms.

Some tips for ideal light conditions:

- Provide morning sun, and afternoon shade in hot climates

- Give more sunlight in cooler northern regions  

- Plant in partly shaded beds under tall trees/shrubs

- Filter harsh sunlight with sheer curtains for potted plants

Adjust sunlight based on your climate and monitor plant health. Leaves yellowing or browning likely indicate too much intense sun exposure.

Conclusion

With proper planting and care, calla lily bulbs will reward you with gorgeous blooms and lush foliage. Follow these tips for ideal planting conditions, moisture, sunlight, and more to help your calla lilies thrive for years of beauty. Pay close attention to planting depth, drainage, and orientation when first planting bulbs to get them off to a healthy start. Callas are a joy in gardens and vases when their needs are met.

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References:

1. University of Minnesota Extension: Growing Calla Lilies

https://extension.umn.edu/flowers/growing-calla-lilies

2. Missouri Botanical Garden: Calla Lily Care

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/calla-lily-care.aspx

3. Royal Horticultural Society: Calla Lily Growing Guide

https://www.rhs.org.uk/plants/calla/growing-guide

4.Clemson University Home & Garden Information Center: Calla Lilies

https://hgic.clemson.edu/factsheet/calla-lilies/

5. North Carolina State University Extension: Calla Lily Production

https://content.ces.ncsu.edu/calla-lily-production

6. The Spruce: How to Grow and Care for Calla Lilies

https://www.thespruce.com/grow-calla-lilies-1902767