What Are Calla Lilies and Why Plant Them Outdoors?
Planting calla lilies outdoors transforms gardens with their striking, elegant trumpet-shaped flowers and lush foliage. Often mistaken for true lilies, calla lilies (Zantedeschia) are herbaceous perennials originating from southern Africa. They are prized for their sophisticated appearance, available in a spectrum of colours from pure white and sunny yellow to deep burgundy and vibrant pink. Growing them outside allows these architectural plants to create a dramatic focal point, whether planted in borders, containers, or massed for a bold statement.
The appeal of planting calla lilies outdoors lies in their ability to add a touch of exotic flair and refined beauty to any landscape. They thrive in warmer climates and can be grown as annuals or overwintered in cooler regions, offering flexibility for many gardeners. Their long, strong stems make them excellent for cut flowers, bringing their unique charm indoors. Understanding their specific needs ensures these showy plants will flourish, rewarding your efforts with impressive blooms throughout the summer and into autumn.
Understanding Calla Lily Rhizomes
Before you begin planting calla lilies outdoors, it is vital to understand what you are planting. Calla lilies grow from rhizomes, which are modified stems that grow horizontally underground. These rhizomes store nutrients and energy, enabling the plant to regrow each season. When purchasing rhizomes, look for plump, firm ones with at least one 'eye' or bud, indicating a healthy start. Avoid any that are soft, mouldy, or dried out, as these are less likely to germinate successfully. Proper identification and selection of healthy rhizomes are the foundational steps for successful outdoor cultivation.
Why Choose Outdoor Planting?
Opting to plant calla lilies outdoors offers distinct advantages over indoor cultivation. Outdoors, they receive ample sunlight, crucial for robust growth and prolific flowering. The natural environment also provides better air circulation, reducing the risk of fungal diseases. Furthermore, planting outdoors allows calla lilies to form substantial clumps over time, creating a more impactful display than is typically possible in pots. The freedom to integrate them into existing garden beds means they can complement other perennial plantings, adding vibrant colour and form to seasonal garden designs. For many, the goal is to replicate their naturalised, lush appearance in a garden setting, which is best achieved outdoors.
Preparing for Planting Calla Lilies Outdoors
Successful outdoor cultivation begins with meticulous preparation. This involves selecting the right location, amending the soil to suit the calla lily's preferences, and understanding the optimal planting times for your climate. Getting these fundamentals right significantly increases the chances of robust growth and abundant blooms.
Choosing the Ideal Planting Site
When planting calla lilies outdoors, the site selection is paramount. Calla lilies prefer a location that receives at least six hours of direct sunlight per day, though they can tolerate partial shade, especially in hotter climates where afternoon shade can be beneficial. The soil should be well-draining; calla lilies detest waterlogged conditions, which can lead to rhizome rot. If your garden soil is heavy clay, consider planting in raised beds or containers filled with a suitable potting mix to ensure adequate drainage. Protection from strong winds is also advisable, as tall stems can be damaged.
Soil Preparation and Fertilisation
Calla lilies thrive in rich, fertile soil. Before planting calla lilies outdoors, incorporate generous amounts of organic matter, such as compost or well-rotted manure, into the planting area. This improves soil structure, drainage, and nutrient content. A slightly acidic to neutral soil pH (between 6.0 and 7.0) is ideal. For containers or beds where soil is less than ideal, a good quality potting mix formulated for flowering plants, mixed with compost, works very well. Once planted, a balanced, slow-release fertiliser formulated for flowering plants can be applied according to package directions, typically starting a few weeks after new growth appears.
Amend your soil thoroughly with compost before planting, as this provides essential nutrients and improves drainage, which is critical for preventing rhizome rot.
When to Plant Calla Lilies Outdoors
The timing for planting calla lilies outdoors is crucial for their establishment. They are sensitive to frost and should only be planted after all danger of frost has passed in the spring. In most temperate climates, this means late spring or early summer. If you are in a very warm region, you might be able to plant earlier, but always wait until the soil has warmed sufficiently. Planting too early can expose the rhizomes to cold, damp conditions that can cause them to rot or fail to sprout. Conversely, planting too late in the season may not allow enough time for the plants to establish and bloom fully before cooler weather arrives.
The Process of Planting Calla Lilies Outdoors
With the site prepared and the timing right, the physical act of planting calla lilies outdoors is straightforward. Following the correct depth and orientation for the rhizomes will set them on the path to successful growth and a season of beautiful blooms.
Rhizome Orientation and Depth
When planting calla lily rhizomes, their orientation is important. Look for the small, knobby protrusions or 'eyes' on the rhizome – these are the growth points. Place the rhizome with the eyes facing upwards. If you cannot clearly distinguish the eyes, it is generally safe to plant them with the curved side up and the flatter side down, or simply lay them flat. The rhizomes should be planted at a depth of approximately 10-15 cm (4-6 inches) below the soil surface. This depth helps to protect them from temperature fluctuations and provides stability as the plant grows.
Spacing Your Plants
Proper spacing is key to allowing calla lilies to grow to their full potential and for good air circulation. When planting calla lilies outdoors in beds, space the rhizomes about 30-45 cm (12-18 inches) apart. This distance allows ample room for the plants to spread and for their foliage to develop without overcrowding, which can reduce flowering and increase the risk of disease. For container planting, you can plant them closer together, typically 15-20 cm (6-8 inches) apart, depending on the container size, but still ensure they are not excessively crowded.
Watering After Planting
After planting your calla lily rhizomes, water the soil thoroughly. This initial watering helps to settle the soil around the rhizomes and begins the process of hydration. For the first few weeks, keep the soil consistently moist but not waterlogged. Once the plants have established and are actively growing, they require regular watering, especially during dry spells. Aim to keep the soil evenly moist, allowing the top centimetre or so to dry out between waterings. Reducing watering slightly as the foliage begins to yellow in late summer or autumn can signal the plant to prepare for dormancy.
The subtle art of planting calla lilies outdoors lies in balancing their need for warmth and moisture with an absolute requirement for good drainage.
Caring for Outdoor Calla Lilies
Once your calla lilies are planted outdoors, ongoing care ensures they remain healthy and continue to produce their iconic blooms. This involves regular watering, feeding, and managing potential issues that might arise.
Ongoing Watering and Feeding Regimen
Consistent moisture is vital for calla lilies, particularly during their active growing season. Water deeply when the top layer of soil feels dry to the touch. Avoid letting the soil become completely parched or waterlogged. As the plants grow, a regular feeding schedule will promote vigorous flowering. Apply a balanced liquid fertiliser, diluted to half strength, every 2-4 weeks from when new growth appears until the flowers begin to fade. Over-fertilising can lead to excessive foliage growth at the expense of blooms, so adhere to recommended dosages.
Pest and Disease Management
While generally robust, calla lilies can be susceptible to certain pests and diseases. Aphids can sometimes infest new growth, and slugs or snails may nibble on leaves and flowers. Regularly inspect your plants for any signs of infestation. Minor aphid problems can often be treated with a strong jet of water or insecticidal soap. For slugs and snails, barriers or manual removal are effective. The most common disease is rhizome rot, caused by overwatering and poor drainage. Ensuring good soil aeration and avoiding soggy conditions are the best preventative measures. If a plant shows signs of wilting despite adequate watering, check the rhizome for rot.
Monitor your plants closely for early signs of pests or disease; prompt action is key to preventing minor issues from becoming significant problems.
Overwintering Calla Lilies in Cooler Climates
Calla lilies are not frost-hardy and will not survive freezing temperatures in the ground. In regions where winters are cold, it is necessary to lift the rhizomes before the first hard frost. Gently dig them up, brush off excess soil, and allow them to dry in a cool, airy place for a few days. Store the dormant rhizomes in a cool, dark, dry location, such as a paper bag or box filled with peat moss or sawdust, over the winter months. Ensure the storage temperature remains above freezing but not too warm, ideally around 7-10°C (45-50°F). Replant them outdoors after the last frost in the spring, initiating the cycle anew.