Wisteria frutescens aka American Wisteria

Wisteria frutescens, or American wisteria, belongs to the pea family. This woody vine grows in the central and eastern United States. Its range runs from Virginia and Illinois to Florida and Texas. It grows along streams, ponds, and rivers, and in wet woods. The vine sheds its leaves each year and grows fast. Its stems wind around supports in a counterclockwise direction.

Garden height reaches about 26–39 feet [8–12 metres]. Some vines reach 40 feet [12.2 metres] or more. Spread reaches about 5–8 feet [1.5–2.5 metres]. Slender stems range from red-brown to gray-brown. Young bark feels smooth, while older bark may flake and peel. The glossy, dark green leaves have a pinnate form. Each leaf has nine to fifteen narrow, pointed leaflets. Young leaves have soft hairs, which disappear as they age.

Fragrant, pea-shaped flowers hang in short, dense racemes. Their shades range from lilac and pale violet to blue. Some flowers have yellow marks. The clusters reach 0.5 feet [0.15 metres] long. Bloom starts as leaves emerge in April or May. Other sources place flowering in May–June or summer. A few more flowers may follow later in summer. Smooth, flat pods ripen toward the end of summer. They reach about 0.42 feet [0.13 metres] long. The pods split in fall, exposing shiny brown seeds.

Give this vine a strong support and a sheltered site. It grows best in moist soil that drains well. Rich soil and full sun help it flower well. It accepts some shade, but not deep shade. It tolerates heat, drought, and compacted soil. Sources list USDA zones 5–9 and UK hardiness H5. Prune twice each year to shape it and aid flowering. Choose its site with care, as it dislikes being moved. Seed-grown vines may take years to bloom.

Train it over an arbor, fence, pergola, or wall. It can also form a screen or a trained tree. Butterflies drink nectar, and several kinds feed on its leaves. It attracts birds, while deer tend to leave it alone. Its roots can add nitrogen to the soil. Aphids, mites, scale, and leaf-chewing insects may attack it. Root rot, leaf spots, mildew, and other diseases can occur. Frost, shade, poor pruning, or excess fertilizer can prevent bloom. PFAF reports food use of flowers, but other sources warn against eating any part. Seeds and pods can cause vomiting, stomach pain, and diarrhea. The plant can harm both people and pets.