Purple heart

About Purple heart

Purple heart is a trailing Mexican spiderwort with fleshy purple stems and long, deep-purple leaves, grown as a houseplant, a hanging basket or a summer bedding plant (NC State, Wisconsin Horticulture). It colors best in sun, turns greenish in shade, and roots from any piece of stem, so one plant is easy to keep going for years. It is a cousin of the garden spiderwort and the inch plant.

Hardy outdoors only in zones 10-11 (NC State; Wisconsin Horticulture says zone 10), where it can spread through beds; it is grown indoors everywhere and can summer outdoors once nights stay above 50 F, the coldest it tolerates (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.

Usually bought as a nursery plant or started from a stem cutting, which roots in water or moist mix (Wisconsin Horticulture, NC State).

Growing it indoors

• Light: Give it a sunny window for the deepest purple; it grows in less light, but the leaves turn greenish and the stems stretch (NC State, Wisconsin Horticulture).
• Water: It is drought tolerant but also takes regular watering, so water when the top of the mix is dry and let the pot drain (Wisconsin Horticulture, NC State). Water less over winter indoors.
• Temperature: It does not tolerate temperatures below 50 F (NC State), so keep it off cold winter glass; MU Extension gives about 55 F nights for its tradescantia cousins.
• Feeding: Feed monthly while it is actively growing; for plants wintered indoors, hold off until growth starts again in spring (Wisconsin Horticulture).
• Repotting: The pages we opened give no schedule; MU Extension's general rule is to repot when roots fill the pot, and old leggy plants are easy to replace from cuttings.

Soil

A well-drained potting mix rich in organic matter (NC State).

Pot in a well-drained potting mix rich in organic matter (NC State).

Feeding

• Spring through fall, during active growth: complete houseplant fertilizer. Monthly (Wisconsin Horticulture).
• Winter indoors: none. Hold off until growth starts again in spring (Wisconsin Horticulture).

Don't feed or water heavily over winter indoors, when growth is slow (Wisconsin Horticulture).

Pests to watch for

Scale insects, Mealybugs, Aphids

In the kitchen

Safety: Low-severity poison (NC State): the sap and leaves can give a red, itchy skin rash, and chewing it irritates the mouth and stomach; Wisconsin Horticulture says the rash is uncommon. Wear gloves when cutting it back if your skin is sensitive.

Pets: Not listed by the ASPCA (no purple heart, purple queen or Setcreasea entry); the ASPCA does list its close relative inch plant (Tradescantia fluminensis) as toxic to dogs and cats, and NC State lists purple heart as a problem for dogs and cats, irritating the mouth and stomach and sometimes the skin.