Ornamental · Pontederiaceae
Pickerelweed
Pontederia cordata
A tough native pond marginal that throws up blue flower spikes all summer, asking only for full sun and wet feet.
Full sun
USDA 3–10
2–4 ft · 0.6–1.2 m
Overview
Pickerelweed is a native aquatic that lines the edges of ponds, ditches, and slow streams across much of North America. It roots in mud at the water's edge and stands its leaves and flower spikes up above the surface, which is what gardeners mean by an emergent marginal. Glossy, heart-shaped leaves form the base, and from early summer into fall it sends up soft spikes of violet-blue flowers.
It earns its keep as a wildlife plant. The flowers feed bees and other pollinators, and ducks and waterfowl eat the seeds and foliage. As a hardy perennial it shrugs off winters from zone 3 all the way to zone 10, dying back in fall and returning from the rhizome each spring.
Two things make or break it. The roots must stay constantly wet to shallowly submerged, since this is a wetland plant that cannot dry out, and the same vigor that fills a pond edge with bloom will run if you let it. Grow it in a basket where space is tight and it stays a generous, well-mannered clump.
Care
The short version: give it full sun and keep its feet wet, rooted in rich mud or loam with the crown under just a few inches of water, and contain the rhizomes in a basket so they don't take over.
Light
Pickerelweed flowers best in full sun, which is where you'll get the most spikes and the strongest growth. It will take partial shade, but expect fewer flowers and a looser, leggier plant in return.
Water
This is a true wetland plant, so the roots must stay constantly wet to shallowly submerged and never dry out. Grow it in mud or rich loam with about 2 to 12 inches (5 to 30 cm) of water over the crown, or in boggy soil right at the water's edge. Plant it any deeper than roughly 12 inches (30 cm) and the extra water over the crown can kill it.
Soil
Root it in rich organic loam or mud that stays constantly wet to submerged. It is easygoing about pH, settling in anywhere from 6.0 to 8.0, so most pond mud suits it without fuss.
Temperature
Pickerelweed is remarkably hardy, taking everything from -40°F (-40°C) in winter dormancy up to about 100°F (38°C) in summer. That range covers zones 3 through 10, so it overwinters in place across most of the country.
Humidity
Growing in or beside water, it never wants for moisture in the air, so humidity is one less thing to manage. The high humidity at a pond edge is exactly where it thrives.
Feeding
It needs little feeding and is largely self-sufficient. If you want to push growth, work an aquatic plant tablet into the soil during the spring-through-summer season, but keep it light, since this plant does fine on its own.
Pruning
Upkeep is minimal. Snap off spent flower spikes through the season, then cut back and clear away the old, dead foliage in late fall or early spring before the new growth starts.
Repotting
Every 2 to 3 years, lift the plant to divide and refresh a crowded clump. The signs it's due are rhizomes bulging the basket, smaller leaves with fewer flowers, and the plant heaving up out of its pot.
Size & spacing
Plants reach 2 to 4 feet (61 to 122 cm) tall and spread 18 to 24 inches (46 to 61 cm) across. Give each clump room to widen, and remember the rhizomes will keep pushing outward past that spread unless a basket holds them in.
When to plant
Pickerelweed follows the warm season. Set divisions or potted plants out in spring once the frost has passed, into mud at the pond margin or a submerged basket, and it rewards you with blue spikes from early summer until fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring; seed germinates best under water and may need cold stratification
- Plant: Spring, after frost, into mud at pond margins or in submerged baskets
- Harvest: Early summer into fall (about June to October)
Hardiness
USDA hardiness zones: 3–10
Temperature: down to -40°C
Troubleshooting
Pickerelweed has no serious pests or diseases, so nearly all of its trouble comes down to two things: it spreads, and it must never dry out. Match what you see below and you can set it right before it spreads too far or declines.
Wilting and browning from drying out or wrong planting depth
This is a wetland plant, and it cannot take drying out even once. If the soil goes dry or merely damp, or the crown sits under more than about a foot of water, the plant browns and stalls. Keep the soil constantly wet to shallowly submerged, and reset the depth so only 2 to 12 inches (5 to 30 cm) of water covers the crown.
Fix:
- Keep the soil constantly wet to shallowly submerged at all times
- Reset the planting depth so only about 2-12 in (5-30 cm) of water covers the crown
- Move container plants to a shallower shelf or raise them on bricks
Spreading rhizomes that crowd a small pond or container
Pickerelweed runs on thick rhizomes, and in open mud it forms dense colonies that push into open water and over its neighbors. Plant it in a submerged aquatic basket from the start so the roots stay where you want them. Lift and divide the clump every 2 to 3 years, and cut back any outlying shoots before they get away from you.
Fix:
- Grow in a submerged aquatic basket or container rather than open mud to confine the rhizomes
- Lift and divide clumps every 2-3 years, discarding excess rhizome
- Pull or cut back outlying shoots to keep the colony in bounds
Minor leaf feeding from aphids, mites, or caterpillars
Pickerelweed has no serious pests or diseases, so any trouble is usually light. Watch for clusters of aphids, the fine webbing and stippling of spider mites, or chewed leaf margins from caterpillars. Hose the small pests off with a strong jet of water, pick off caterpillars by hand, and let the plant shrug off the rest, which it usually does.
Fix:
- Hose pests off with a strong jet of water
- Hand-pick caterpillars
- Tolerate minor damage, since this plant has no serious insect or disease problems and usually outgrows it
Toxicity
Good news for pet owners and gardeners alike: pickerelweed is non-toxic to people and animals, and parts of it are actually edible. The young leaves and ripe seeds have long been eaten, and the plant is a valued food for ducks and other wildlife. Since it grows in standing water, the only real caution is the usual supervision around a pond.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Safe for cats. A curious nibble at the leaves won't cause any poisoning, though pond water is reason enough for normal supervision.
Dogs None
No toxic compounds here, so a dog that grabs a mouthful of foliage is in no danger from the plant itself.
Horses Safe
Horses can graze the leaves at a pond edge without harm, since nothing in the plant is poisonous to them.
Rabbits Safe
The tender leaves are fine for rabbits and carry no toxins, making this a worry-free marginal around a hutch or pond.
Livestock Safe
Cattle, goats, and sheep can browse it safely. The plant is non-toxic and actually feeds a range of grazing and wild animals.
Birds Safe
Far from a hazard, the seeds and foliage are a prized food for ducks and other waterfowl, with no risk to backyard or wild birds.
People Safe
Safe for people, and the young leaves and seeds are edible. Cook young leaves like a green and eat the ripe seeds raw or roasted.
No special handling precautions; the plant is safe and even edible. It lives in standing water, so normal supervision around ponds applies.
Varieties
Most pickerelweed sold is the straight blue-flowered species, but a couple of selections turn up worth knowing.
'Alba'
A white-flowered selection that sends up tall spikes of white blooms from summer into fall in place of the usual blue.
var. lancifolia
A narrow-leaved form whose foliage is more lance-shaped than the heart-shaped leaves of the typical plant.
Companions
Pickerelweed plays well with other native marginals and pond plants that share its taste for full sun and wet ground, layering the pond edge with different heights and leaf shapes.
Plant near
Water lily (Nymphaea): A classic pond pairing: pickerelweed's vertical blue spikes at the margin complement floating-leaved water lilies in deeper water.
Arrowhead (Sagittaria latifolia): Another native marginal sharing the same shallow-water, full-sun habitat for a layered pond-edge planting.
How to propagate
You can multiply pickerelweed two ways, and one is far quicker than the other.
DivisionEasy
Spring · One growing season
Division is the easiest and most reliable way to multiply pickerelweed. In spring, dig an established clump and cut the thick rhizomes apart, making sure each piece has roots and a shoot. The new divisions settle in and fill out over a single growing season.
SeedModerate
Late winter to spring · One to two growing seasons
Seed takes more patience and works best sown from late winter into spring. Germination is strongest under water, even after dry storage, and a spell of cold stratification helps. Give seed-grown plants one to two growing seasons to reach a good size.
Myths
Pickerelweed is the same plant as water hyacinth and just as invasive.
They are two different plants. Native pickerelweed is a rooted emergent that anchors in pond mud and stays put, while water hyacinth is a free-floating weed notorious for choking waterways. Both sit in the family Pontederiaceae, but pickerelweed is a well-behaved native, not the invasive floater.