Trillium (T. grandiflora) is one of the most popular wildflowers in North America. It grows from coast to coast and is found throughout much of Canada, Mexico, Central America and South America. The species name means “grandmother’s flower” because it was first described in 1825 by William Henry Harrison, a botanist at Harvard University who lived near Mount Desert Island in Massachusetts.
Trillium is native to the northern United States, but it has been introduced into many other countries including Australia, New Zealand and Europe. Its range extends northward along the Atlantic Coast from Maine south through Canada and eastward across Pennsylvania, Maryland and Virginia. It is common in open areas such as fields, pastures and woodlands where light levels are low.
Trillium prefers moist soil with a pH between 6.0–7.5. Trillium prefers full sun and will grow well even if kept indoors during winter months. It is not frost tender, though it may become dormant in cold weather.
The flowers of trillium are white or pale pink, up to three inches long and have five petals each. They are arranged in a cluster on short stalks called racemes. The leaves are broad and shaped like a spade with rough edges.
The size of the flowers and leaves varies among the different species and varieties of trillium.
Trilliums grow from a large, fleshy underground tuber or rhizome, which produces new clumps or bulblets that can be separated and replanted. All trilliums have 3 leaves and 3 flowers, hence the name.
There are 15 species of trilliums in the U.S. and Canada, some of which are hard to tell apart.
In addition, various subspecies and color variations have been given their own names. There are over 20 varieties and subspecies of trilliums known to grow in the wild in the U.S. and Canada. That does not count the many cultivated varieties that have been hybridized or developed in gardens.
Trilliums prefer a humus-rich, well-drained soil and partial shade to full sun. Large clumps of trillium can be divided, and individual bulblets separated from the parent tuber. In moist areas, they also grow well in dry, wooded areas with partial shade.
Trilliums can be grown underneath trees that allow some light through but too much sun will dry out the soil too much. Trilliums also look nice when grown in a grove of redwoods or other conifers. The soil needs to be kept consistently moist but not soggy.
Trilliums love shaded areas underneath deciduous trees such as oak or beech but will also tolerate full sun if the soil is kept consistently moist. They grow best in humus-rich soil with a pH between 5.5 and 7.0.
Trilliums need consistent moisture throughout the growing season. During hot, dry spells, they should be watered once a week or they will wilt and die. They can be planted in groups or clusters of three to five bulbs three to six inches apart in shaded areas with fertile, moist soil that has been enriched with leaf mold and other organic matter.