Understanding Arum Lilies (Zantedeschia)
Arum lilies, botanically classified under the Zantedeschia genus and often referred to as Calla lilies, are a popular choice for gardeners seeking elegance and visual impact. Despite the common name, they are not true lilies but are renowned for their distinctive spathes, which are often mistaken for petals, surrounding a central spadix. These plants thrive in a variety of conditions, provided their specific requirements are met, making them a rewarding addition to many garden styles, from formal beds to contemporary designs. Their lush, arrow-shaped leaves add a tropical feel even before the characteristic blooms appear.
These striking plants typically present their flowers from late spring through summer, though this can vary based on variety and local climate. While white is the most iconic colour, modern cultivars boast an impressive spectrum including deep purples, vibrant yellows, soft pinks, and rich reds. They are often grown from rhizomes, which are thick, fleshy underground stems that store nutrients, enabling the plant to regrow year after year. Proper planting and care of these rhizomes are fundamental to achieving abundant flowering and healthy growth.
- Arum lilies (Zantedeschia) have trumpet-shaped spathes, not true petals.
- They offer a range of colours beyond white.
- Rhizomes are the primary method of propagation and overwintering.
- Lush foliage adds ornamental value.
- Flowering typically occurs from late spring through summer.
Rhizome Planting Guide
When planting arum lily rhizomes, select a location that receives ample sunlight – ideally 6-8 hours per day. While they can tolerate partial shade, flowering may be reduced. The soil should be fertile, well-draining, and consistently moist. Prepare the planting site by incorporating compost or other organic matter to enrich the soil and improve its structure.
Plant the rhizomes about 10-15 cm deep, with the growing points (where shoots will emerge) facing upwards. If unsure, plant them horizontally or slightly angled with the growing points up. Space rhizomes approximately 30-45 cm apart to allow for full growth and air circulation, which helps prevent fungal diseases. Water thoroughly after planting. If planting in containers, use a good quality potting mix and ensure the pot has adequate drainage holes.
Essential Care for Arum Lilies
The key to thriving arum lilies lies in managing their water and feeding regimes. These plants, particularly when grown in warmer climates or during dry spells, appreciate consistent moisture. Aim to keep the soil damp but not waterlogged. Overwatering can lead to root rot, especially in poorly draining soil, while severe underwatering can cause the leaves to wilt and yellow.
During the growing season, from spring through to late summer, a regular feeding schedule can significantly boost flowering. A balanced, water-soluble fertiliser applied every 2-4 weeks will provide the necessary nutrients. Alternatively, incorporating a slow-release fertiliser at the start of the season can offer sustained feeding. As the plant enters dormancy, typically in autumn, reduce watering and cease feeding to allow the rhizomes to prepare for rest.
Winter Care and Dormancy
In regions with mild winters, arum lilies may remain evergreen and can be left in the ground. However, they benefit from a layer of mulch to protect the rhizomes from extreme cold. For gardeners in colder climates where frosts are common, it is advisable to lift the rhizomes before the first hard frost. Dig them up carefully, trim off any dead foliage, and allow them to dry in a cool, well-ventilated area for a few days. Store the dry rhizomes in a frost-free location, such as a shed or garage, packed in peat, sand, or vermiculite, until spring planting time.
Protect new growth in spring by covering emerging shoots with fleece if late frosts are predicted, as young leaves are particularly susceptible to damage.
Pest and Disease Management
Arum lilies are generally robust, but can occasionally be affected by pests such as aphids or slugs. Regular inspection of the foliage and stems can help catch infestations early. Slugs and snails can be deterred using barriers or specific treatments. Fungal diseases, like leaf spot or root rot, are usually a consequence of poor air circulation or overwatering. Ensuring adequate spacing between plants and avoiding waterlogged soil are the best preventative measures.
Exploring Arum Lily Varieties and Alternatives
The Zantedeschia genus offers a diverse range of colours and sizes, moving beyond the classic white Calla lily. Varieties like 'Black Star' offer deep, almost black-red blooms, while 'Picasso' displays a striking white edge on its purple flowers. 'Mango' and 'Crystal Clear' showcase vibrant oranges and pale pinks respectively, providing ample choice for various garden palettes and design schemes. Each cultivar has slightly different growth habits and flowering times, so it's worth researching specific types before purchasing.
The true beauty of selecting arum lilies lies in their adaptable elegance, fitting seamlessly into both dramatic statements and subtle garden compositions.
Choosing Complementary Plants
When planning a planting scheme, consider companions that complement the arum lily's form and colour. For a lush, tropical feel, plants such as hostas, ferns, and ornamental grasses pair well. Their varied textures and shades of green can create a rich tapestry. For a more formal look, consider pairing them with plants that share a similar colour palette or structure, such as certain types of lilies, irises, or even neatly clipped boxwood.
Considering Other Bulbs and Rhizomes
If you admire the impact of arum lilies but wish to explore other striking bulbous or rhizomatous plants, several excellent alternatives exist. For vibrant spring colour, consider tulip bulbs, which come in an astonishing array of shapes and hues. Daffodils offer cheerful yellow and white displays, while the architectural elegance of allium species provides unique spherical flower heads. For summer interest, gladioli offer tall spikes of colour, and other varieties of true lilies provide diverse forms and fragrances. Even smaller bulbs like bluebells and snowdrops create enchanting displays in different seasons and settings, offering a wide spectrum of floral beauty.
When planting a mix of bulbs and rhizomes for sequential flowering, always check the individual planting depth and spacing requirements for each species to ensure optimal growth for all.
Evaluating Flower Forms
The unique funnel shape of arum lilies stands out. If you appreciate this form but are looking for different seasonal interest or colour, consider plants with similar architectural qualities. For example, the bell-shaped flowers of campanulas or the trumpet-like blooms of some digitalis (foxgloves) offer comparable visual impact, though they grow from different plant types and require distinct care. Exploring different flower shapes can significantly broaden your garden's aesthetic appeal throughout the year.