Spiderwort

About Spiderwort

Spiderworts are easygoing native perennials with grassy, arching leaves and clusters of three-petaled blue, purple, pink or white flowers that each open for just one morning, with new ones every day from late spring into summer (Penn State, NC State). Ohio spiderwort grows wild from Massachusetts to southeast Minnesota and south to Florida and east Texas, and Virginia spiderwort across the east-central and eastern U.S.; the garden Andersoniana hybrids are more compact (Wildflower Center, NC State, Penn State). They spread by creeping stems and seed and can take over a bed, so give them room or divide them often.

Hardy in zones 4-9 (NC State, Penn State). Not listed as invasive in the U.S., but garden spiderworts can spread aggressively by runners and seed (Penn State), and Virginia spiderwort has escaped in parts of California and Europe (NC State). Wild Virginia spiderwort is getting scarcer in the Carolinas, so buy nursery-propagated plants (NC State).

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Easiest from divisions or cuttings: divide clumps in early fall or very early spring into pieces with 4-6 shoots and roots, and replant right away (USDA NRCS, Wildflower Center). Seed needs about 120 days of cold, moist treatment, or sow it unstratified outdoors in fall (Wildflower Center). No sourced day count to first bloom.

Soil

Moist, fertile soil is best, but it adapts to average, sandy, clay or occasionally wet soil and short dry spells; good in rain gardens. Give it shelter from hot afternoon sun (Penn State, NC State).

Work some compost into the bed; spiderworts like moist, fertile soil but adapt to average garden soil (NC State, USDA NRCS).

Feeding

• Early spring, just before new shoots come up (only if a soil test or weak growth calls for it): complete slow-release fertilizer such as 12-6-6. Without a soil test, Clemson suggests 1-2 lb per 100 sq ft of bed for perennials; keep it off the leaves and water it in.

Most perennials need little fertilizer, and overfed plants grow soft with few flowers (Penn State). Divide every 2-4 years and pull stems that lie on the ground before they root, or the patch will spread (USDA NRCS).

Harvest

Blooms May into July, often with a second flush in late summer or fall (Penn State, NC State). Each flower lasts a day and opens in the morning. When the foliage flops after bloom (often early July), cut plants back to a few inches; fresh leaves and often more flowers follow (Penn State, USDA NRCS). Good for cutting (NC State).

Varieties (18)

Good neighbors

Milkweed, Bee balm

Penn State suggests butterfly weed, whorled milkweed and scarlet bee balm to hide spiderwort's untidy summer foliage; this is a design pairing, not a pest-control claim.

Pests to watch for

Brown garden snail, Rabbits

Diseases and problems

Tomato and tobacco ringspot

In the kitchen

Safety: NC State rates Virginia spiderwort as mildly toxic: eating it can upset the mouth and stomach, and the sap can redden and itch sensitive skin, so wear gloves. Some sources call the young leaves edible, but because sources disagree we don't suggest eating it.

Pets: Garden spiderworts are not listed by the ASPCA (no spiderwort entry on its dog, cat or horse lists). The ASPCA does list a related houseplant, inch plant (Tradescantia fluminensis), as toxic to dogs, cats and horses, causing skin irritation (dermatitis), and NC State lists Virginia spiderwort as mildly toxic to dogs and cats.