Curly Pondweed (Crispus)

The Curly Pondweed (Crispus) is generally described as a perennial forb/herb. This is not native to the U.S. (United States) and has its most active growth period in the spring and summer and fall . The greatest bloom is usually observed in the mid spring, with fruit and seed production starting in the spring and continuing until summer. Leaves are not retained year to year. The Curly Pondweed (Crispus) has a short life span relative to most other plant species and a rapid growth rate.

The Curly Pondweed (Crispus) is not commonly available from nurseries, garden stores and other plant dealers and distributors. It can be propagated by bare root, seed, sprigs. It has a moderate ability to spread through seed production and the seedlings have medium vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -33°F. has none tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Wildlife: Curly pondweed tends to increase oxygen levels and produce substantial organic material in aquatic environments (Guard 1995). This pondweed shelters small fish and aquatic insects that provide food for larger fish and amphibians (Ibid.).

General Characteristics

General: Pondweed family (Potamogetonaceae). Curly pondweed is an introduced, fast growing perennial. The stems are flattened and somewhat branching, forty to eighty centimeters long and mostly one to two millimeters wide (Guard 1995). The leaves are simple, long, narrow and attached directly to the stem. The flowers are brownish and inconspicuous and usually occur from May to October.

Required Growing Conditions

Curly pondweed has been introduced from Massachusetts to Minnesota, south to Virginia and Missouri (Tiner 1987). For current distribution, please consult the Plant profile page for this species on the PLANTS Web site.

Adaptation This species has invasive qualities. Curly pondweed is commonly found in ponds, lakes, canals, pools and slow moving water of rivers and streams. This plant grows well in sandy, loamy and clay soils. It prefers acid, neutral and basic soil and can grow in very alkaline and saline soils. This species is not shade tolerant.

Cultivation and Care

Propagation by Seed: Curly pondweed seeds should be sown as soon as they are ripe, in summer or early autumn (Heuser 1997). The seeds lose viability quickly if they are allowed to dry out (Ibid). Prick out the seedlings when they are large enough to handle and increase the depth of water around the pot until the plants are covered by a few centimeters of water. Grow the plants in a sunny position in the greenhouse for their first winter, increasing the depth of water, as the plants grow larger. Plant them out into their permanent positions in early summer.


Introduced into the U.S. Considered a pest by several sources.

General Upkeep and Control

Curly pondweed is an aquatic plant that can be used as an oxygenator of ponds. This species sometimes becomes a pest in waterways lakes and reservoirs (Guard 1995). It is a fast growing plant in need of constant checking to make sure it does not overrun ponds, pools or canals.

Plant Basics
Growth Rate Rapid
General Type Forb/herb
Growth Period Spring, Summer, Fall
Growth Duration Perennial
Lifespan Short
Plant Nativity Introduced to U.S.
Commercial Availability No Known Source
Physical Characteristics
Bloom Period Mid Spring
Displays Fall Colors No
Shape/Growth Form Single Crown
Drought Tolerance None
Shade Tolerance Intolerant
Vegetative Spread Slow
Flower Color Green
Flower Conspicuousness No
Fruit/Seed Abundance Medium
Fruit/Seed Seasonality Spring Summer
Seed Spread Rate Moderate
Gardening Characteristics
Propagations (Ways to Grow) Bare Root, Seed, Sprigs
Moisture Requirements High
Cold Stratification Required No
Minimum Temperature -33
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate None
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 6.4–8.5 pH
Precipitation Range 12–12 inches/yr
Planting Density 1700–4800 indiv./acre
Minimum Frost-Free Days 100 day(s)
Salinity Tolerance None
CaCO3 Tolerance Low
Sustainability & Use
Leaf Retention No
Fire Resistant No

Source: USDA, NRCS, PLANTS Database,
National Plant Data Center, Baton Rouge, LA 70874-4490 USA