Alstroemeria

Fundamental Facts

HARDINESS: Zones 6 to 9
PREFERRED SOIL pH: Slightly acid
PREFERRED SOIL TYPE: Well-drained
PREFERRED LIGHT: Sun to partial shade
ATTRIBUTES: Speckled lilylike blossoms in many colors; for beds, cutting, pots
SEASON OF INTEREST: Early summer
FAVORITES: Yellow-flowered 'Sweet Laura'; 'Compact Red'
QUIRKS: Foliage dies back after flowers fade
GOOD NEIGHBORS: Gypsophila, lavender, lilies
WHERE IT GROWS BEST: Widely adaptable to soils and sites with sun to partial shade
POTENTIAL PROBLEMS: Root injury in subfreezing winters
RENEWING PLANTS: Lives for years; dividing not recommended
CRITTER RESISTANCE: Good
PLANTING DEPTH: 6-8 in (15.2-20.3 cm)
SOURCE: Bare root plants
DIMENSIONS: 2-5 ft (0.6-1.5 m) tall, mature clumps often 3 ft (1 m wide)

Alstroemeria in the Landscape

Most gardeners meet alstroemeria for the first time in restaurants, where the cut flowers are frequently used as table ornaments. Because the freckled tubular blossoms can last more than 2 weeks in a vase, alstroemerias are often the flower of choice in public places and are included in many florists' bouquets. Also known as Peruvian lilies, these beauties have been grown little outside of very warm climates, as most older cultivars suffered badly from cold winters and were too tall and rangy to make good container plants. In the last few years, however, both of these limitations have been overcome. New varieties, such as the yellow-flowered 'Sweet Laura', are hardy enough to survive in Zone 6, and compact versions, such as Meyer's Hybrids and 'Compact Red' fit in roomy pots or small raised beds.

When planted in the garden, alstroemerias grow 30 in (76.2 cm) tall, with the bulk of the flowers rising on thin, sturdy stems in early summer. The alstroemerias that grow well in a wide range of climates have flowers that are either yellow or deep orange, though it is possible to find varieties with purple, white, lavender, or pink flowers. Alstroemeria leaves are narrow, slightly twisted, and usually medium green. When grown near perennials that like similar growing conditions, such as gypsophila or lavender, alstroemerias can become garden standouts.

Alstroemeria Basics

Alstroemeria is a member of the lily family, and its trumpetlike blossoms do resemble those of the lily. However, rather than growing from true bulbs, alstroemerias grow from thick, brittle roots. In the garden the roots spread outward, forming colonies. If left untended the plants can become weedy looking, but this is easily avoided by clipping off old flowers and foliage in midsummer. This grooming is really the only maintenance that alstroemerias require.

Like other lilies, alstroemerias need excellent drainage. Plant in deep, loamy soil that holds moisture well in spring and early summer and dries out almost completely in the fall. If your soil is heavy clay, it is best to grow these flowers in raised beds.

Growing Alstroemeria

Set out container-grown plants in fall, even though they may look ragged or dormant. Carefully set the fleshy roots in well-dug beds, covering them with 6 in (15.2 cm) of soil. The plants will not emerge until spring and may not bloom well until the following year. After alstromerias are planted, it is best to leave them alone, because digging and dividing always reduces flowering for at least a year, and the brittle roots are easily damaged.

In Zones 6 and 7, after the first hard freeze of autumn, pile a fluffy, insulating mulch, such as evergreen boughs or straw, over alstroemerias at least 4 in (10.2 cm) deep. As long as the soil does not freeze hard to the depth at which the roots are planted, the plants will endure a cold winter. Cold injury caused by shallow planting or prolonged freezing is the main problem you are likely to have with these durable plants. They are otherwise untroubled by pests or diseases.