Stachytarpheta spp.

porterweeds

Verbenaceae Tropical and subtropical Americas

Attracts Pollinators Attracts Butterflies Attracts Hummingbirds Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterMedium

HardinessZones 9–11

Overview

Stachytarpheta spp. is a genus of about 130 herbs, subshrubs, and shrubs in the family Verbenaceae, known as porterweeds, native to tropical and subtropical America. Plants grow 2-6 feet (0.6-1.8 m) tall with branching stems and coarse, toothed, dark green leaves 1-5 inches (2.5-13 cm) long. The flowers are small, about 0.3-0.6 inch (8-15 mm) wide, and set into slender erect or arching spikes 6-20 inches (15-50 cm) long, opening a few at a time along the spike from the base upward. Flower color ranges across blue, purple, red, pink, and white depending on species. Several species are grown in warm-climate gardens and draw butterflies, bees, and hummingbirds to the nectar-rich flowers. The genus grows as a tender evergreen in frost-free climates and is treated as an annual or container plant in regions with cold winters. Plants bloom over a long season in heat but stop in cool weather and die at frost. Some species, such as S. cayennensis, have naturalized and become weedy in tropical regions outside their native range.

Native Range

Stachytarpheta spp. is native to tropical and subtropical parts of the Americas, from the southern United States and Mexico through Central America, the Caribbean, and South America. Several species have naturalized across tropical Africa, Asia, the Pacific, and Australia, where they grow on roadsides and disturbed land.

Suggested Uses

Grown in pollinator and butterfly gardens, mixed borders, and large containers in warm climates. Taller species are used as informal flowering screens, and trailing types suit hanging baskets. The genus is grown for a long warm-season nectar source.

How to Identify

Identify Stachytarpheta spp. by the long, slender flower spike in which small tubular flowers sit partly embedded in the thickened stalk, opening a few at a time in a ring that moves up the spike. Leaves are opposite, toothed, and rough-textured. The blue or purple flowers of S. jamaicensis are a common identifying feature among cultivated species.

Appearance

Size & Dimensions

Height2' - 6'

Width/Spread2' - 4'

Colors

Flower Colors

red

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~20 weeks

Summer Fall

Flowering continues over a long warm season, in frost-free climates nearly year-round and elsewhere from late spring until frost. A small number of flowers open each day along each spike, so a plant carries many spikes in different stages at once. Bloom stops in cool weather.

Detailed Descriptions

Flower Description

blue, purple, red, pink, or white

Foliage Description

dark green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

Reaches flowering size in one season

Care & Maintenance

Care Guide

Stachytarpheta spp. species grow in full sun to light shade in moist, well-drained soil with a pH near 6.0-7.5. The genus needs warmth and steady moisture for continuous bloom and stops flowering in cool conditions. Plants tolerate heat and humidity and recover quickly after cutting back. In frost-free zones 9b-11 they grow as evergreen perennials, while in colder areas they are grown as annuals or overwintered indoors. Light feeding during the growing season supports the long bloom period. Drought slows flowering and causes leaf drop.

Pruning

Stems are cut back by a third during the growing season to keep plants bushy and to renew the flowering spikes. Clearing old spikes brings on new ones. In frost-free climates a hard cutback in early spring controls size and shape.