Alstroemeria, commonly known as the Peruvian Lily or Lily of the Incas, is a popular perennial valued for its vibrant flowers and exceptional vase life. These tuberous-rooted perennials offer a continuous display of color from late spring until the first frost, making them a favored choice for garden borders and containers. The lily-like flowers display a wide spectrum of colors, often adorned with unique speckles and stripes. Successful cultivation relies on understanding its specific environmental needs and implementing targeted care practices.
Establishing the Plant: Location and Soil Requirements
Selecting the correct planting location is the first step toward a thriving Peruvian Lily, as it needs a balance of sun and shelter. The plant performs best in full sun, though in hot regions, afternoon shade prevents scorching and the production of “blind stems” (foliage without flowers). Taller varieties should be placed in a sheltered area, as strong winds can easily damage their flower-laden stems.
The soil must be fertile, rich in organic matter, and possess excellent drainage. Alstroemeria grows from fleshy, tuberous roots, which are highly susceptible to rot if the soil remains waterlogged, especially during winter. Incorporating materials like compost or grit will significantly improve both fertility and drainage. Peruvian Lilies prefer a neutral to slightly acidic pH (6.0 to 7.0), but they can tolerate a range if the drainage is adequate.
When planting, handle the tuberous roots with care and space individual plants one to two feet apart, depending on the variety’s mature width. Planting the tubers relatively deeply, about 7 inches down, helps protect them from frost and aids establishment. For container-grown plants, use a high-quality, free-draining potting mix, often amended with grit, and select a pot with a depth of at least 30-40 centimeters.
Routine Care: Watering and Feeding Schedules
Consistent moisture is necessary for the Peruvian Lily during active growth, but overwatering must be avoided to protect the sensitive tuberous roots. Newly planted specimens require regular watering until they establish. Once settled, they can handle short periods of drought, but during extended dry periods, deep watering once or twice a week is a good guideline.
Watering should be directed at the base of the plant to keep the foliage dry, minimizing the risk of fungal diseases. Container plants dry out faster than those in the ground and require more frequent hydration, often needing water whenever the top inch of soil feels dry. Applying a layer of organic mulch around the root zone helps conserve soil moisture and maintain a cooler temperature for the rhizomes.
Fertilization encourages continuous flowering throughout the growing season. Apply a balanced, slow-release fertilizer in the spring as new growth begins. Following this, feed monthly with a water-soluble fertilizer formulated for flowering plants, which typically has lower nitrogen and higher potassium content. Avoid excessive nitrogen, as it promotes lush foliage growth at the expense of flowers.
Seasonal Maintenance: Deadheading and Winter Preparation
The unique deadheading technique for Alstroemeria directly impacts subsequent flower production. Unlike many perennials where spent blooms are clipped off, the entire flowering stem should be removed. Grasp the stem low near the base and gently pull it with a quick, firm tug. This method severs the stem below ground, stimulating the plant to produce a new flowering shoot.
Cutting the stem instead of pulling leaves behind a stub that can rot and does not encourage new blooms from the base. This pulling action mimics the natural harvesting process used by commercial growers to ensure a steady crop and reinvigorate the clump. Removing spent stems regularly keeps the plant tidy and prevents it from expending energy on setting seed, extending the flowering period until frost.
In colder regions, particularly below USDA Zone 7, winter preparation is necessary to protect the rhizomes from freezing. Once the foliage dies back in autumn, apply a substantial layer of organic mulch, such as straw or shredded leaves, over the planting area. This protective layer insulates the roots and helps the plant successfully overwinter. Container-grown plants should be moved to a cool, frost-free location for the winter, watering them sparingly to prevent the soil from completely drying out.
Addressing Common Pests and Diseases
Alstroemeria is generally a robust plant, but it can be affected by several common garden pests. Pests such as aphids, spider mites, and thrips feed by sucking juices from the leaves and stems, leading to distorted growth or a speckled appearance. Slugs and snails also pose a threat, particularly to tender new shoots emerging in the spring.
Infestations of aphids and spider mites can be managed by introducing natural predators or by washing the foliage with a strong spray of water or insecticidal soap. For slugs and snails, protective barriers or commercial baits can deter them from reaching young growth. Vigilance and early detection are beneficial for controlling these populations.
The primary disease concern for Peruvian Lilies is fungal root rot, which is almost always a result of overly wet or poorly draining soil. Symptoms include wilting and yellowing leaves and weak stems, even when the plant has been watered sufficiently. To mitigate this, ensure the soil is highly porous and avoid excessive watering, especially in cooler weather. Fungal issues like Botrytis, or gray mold, can also occur in overly wet or crowded conditions where air circulation is poor, appearing as a gray, fuzzy growth on the plant. Adequate spacing between plants helps promote air flow, and removing affected plant parts can limit the spread of the disease.