While the saying "Leaves of three, let it be," warrants attention in woodlands to help identify poison ivy, the three diamond-shaped leaves of trillium and their springtime flowers make them worthy of a saying, "Leaves and petals of three, I want to see." Native to North America or eastern Asia, trilliums also may be called wakerobins, wood lilies or trinity flowers. They make rewarding slow-growing yet delicate perennials for woodland gardens and shady borders and rockeries in temperate climate regions.
Trilliums are most readily purchased from native plant nurseries or specially garden centers with extensive shade plant inventories. Usually grown in plastic containers that are ready to plant, sometimes a plant enthusiast may provide you fresh trillium seed to sow, tiny seedlings or bare-rooted root divisions for immediate transplanting in late summer or early autumn. There are 30 species of trilliums, and in general they are slow-growing, taking seven years before producing their first flowers after germinating from seed, according to Growing Wisdom's online interview with staff at the New England Wildflower Society's Garden in the Woods in Massachusetts. Purchasing nursery-propagated, container-grown plants, although more expensive, provides immediate results in the garden setting.
Locate an area in your garden that is protected from direct sunlight, such as under a tall shade tree or on the perpetually shaded side of a building foundation. Early morning or dusk sunlight is weak enough not to cause any damage to the foliage. Check to make sure the soil is moist but well-draining, not remaining soggy or waterlogged after rainfall or irrigation. Deep soils, those that extend downward to at least eight to 10 inches are best; shallower soils dry out more quickly or do not allow for full root expansion.
Trilliums grow considerably better in crumbly soils that are rich in organic matter like leaf mold, compost or well-cured manure.Test the pH of the soil. Plant trilliums in nonalkaline soils with a reading of less than 7.2. Some species tolerate pH as high as 8.0, but organic matter helps these plants grow well in more alkaline conditions. Each summer and autumn, after the trilliums' foliage disappears into dormancy, cast decomposed leaf compost or other organic matter across the bed. The constant renewal of compost and seasonally falling leaves from trees sustains the trilliums with nutrients, so man-made fertilizers are not necessary.
Trilliums require a consistently moist and cool soil across the growing season. Mulching with organic matter helps the soil reach both these conditions. Across summer, 1 inch of rainfall or irrigation weekly sustains plants; keep in mind clay soils retain moisture better and sandier soils dry out more quickly. Increase or decrease supplemental watering as needed based on how quickly the soils dry out in your garden.
Trillium foliage appears in very early spring, followed by flowers, and by early summer the leaves and stems already may die back to the ground. Deer tend to browse upon trilliums, so a fence or chicken wire cage over a cluster of trilliums in spring may deter hungry animals from destroying new foliage or opening flower buds. If you choose to dig up, divide or relocate trillium plants, the ideal time is late summer to early fall, when the plants are dormant underground. Mark the plants in late spring with a wire utility flag or other stick so you know where to properly dig when no plant leaves remain. Slice into the soil with a garden shovel away from the perceived center of the clump so you lessen chances of destroying healthy root rhizomes in the process. Once dug up, retain as much soil on the roots themselves during the transplanting process. Plant them the same depth in the new planting hole as they were growing in the original location.