How to Grow Spike Rush
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Spike Rush
Eleocharis dulcis
grassSpike Rush, also known as Chinese water chestnut, is an aquatic or semi-aquatic sedge native to Asia. It produces edible tubers beneath the soil and small, inconspicuous brown flower spikes. This plant thrives in wetland environments and shallow water conditions.
When should you plant Spike Rush in your zone?
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Example Spike Rush timeline · Pittsburgh, PA (Zone 6b)
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Plant Spike Rush
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Spike Rush
Around Aug 15≈ 120 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Spike Rush dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Zones 9-11; best in warm climates with extended growing seasons
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Get my Spike Rush timeline →Growth Stages
Sprouting
2-4 weeksSmall green shoots emerge from planted tubers; very slow initial growth in cool conditions
Maintain warm water temperatures (70-85°F); keep soil consistently saturated. Ensure good drainage around growing area.
Vegetative Growth
6-10 weeksThin, upright grass-like stems grow 12-24 inches tall; roots and runners spread through moist soil
Provide consistent water and warmth; fertilize monthly with aquatic plant or diluted fertilizer. Monitor for pest activity.
Runner Development
6-12 weeksUnderground stolons (runners) extend from the base plant, producing small tubers at their tips
Maintain warm temperatures and saturated soil. This stage is critical for tuber formation; ensure nutrients are available.
Tuber Formation & Maturation
8-12 weeksSmall, round, chestnut-brown tubers develop at the ends of runners beneath the soil; plant foliage remains green
Do not disturb soil; maintain consistently wet conditions and warmth. Avoid major disturbances to allow tuber development.
Harvest & Storage
Variable; harvest 4-6 months after plantingTubers reach 0.5-1 inch diameter and develop firm skin; foliage may begin to yellow as season progresses
Harvest when tubers are firm; carefully dig and separate from runners. Store in cool, moist conditions.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Remove infested leaves; use neem oil spray on emerged foliage; maintain healthy water conditions
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and
Hand-pick from foliage; maintain predatory fish in water features; remove decaying vegetation
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Ensure good water circulation; avoid stagnant, foul-smelling water; treat with fungicide if necessary
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Improve water circulation; remove excess organic debris; use biological controls if severe
Uses
Water Chestnut Culinary Use
CulinaryThe tubers are eaten as a vegetable in Asian cuisine, commonly used in stir-fries, soups, and salads. They have a crisp, slightly sweet texture and are valued for their crunch even after cooking. [source]
Raw Consumption
CulinaryTubers can be eaten raw after peeling, offering a refreshing snack with a texture similar to jicama or apple. They are low in calories and contain dietary fiber. [source]
Aquatic Gardening & Water Feature Plant
HouseholdThe plant is used to beautify ponds, water gardens, and wetland landscapes. It helps oxygenate water and provides natural filtration in aquatic ecosystems. [source]
Traditional Medicine
MedicinalIn Traditional Chinese Medicine, Eleocharis dulcis tubers are used to support digestive health and are believed to have cooling properties. They are used in herbal soups and remedies. [source]
Waterfowl & Aquatic Habitat
WildlifeThe plant provides food and shelter for ducks, geese, and other aquatic birds. It creates a naturalized wetland environment supporting biodiversity. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Harvest tubers 4-6 months after planting when they reach 0.5-1 inch diameter and have firm, brown skin. Carefully dig or wade into the soil and gently separate tubers from the runner system without breaking them. Handle tubers gently to avoid bruising. Store in cool, humid conditions (50-60°F) for 1-2 weeks, or refrigerate for longer storage. Can be eaten raw or cooked; peel off the brown skin before use.
Fun Facts
- 🌱 Eleocharis dulcis tubers are commercially canned and exported globally, particularly from China and Southeast Asia, making them a significant agricultural crop in warm regions.
- 🌱 The plant is sometimes called 'Chinese water chestnut' or 'water chestnut' in English, though true water chestnuts belong to a different genus (Trapa); despite the name confusion, Eleocharis dulcis is the most commonly cultivated 'water chestnut' in commerce.
- 🌱 Spike Rush is incredibly productive in ideal conditions—a single plant can produce dozens of tubers in a single season through its spreading runner system, making it an excellent choice for home aquatic gardeners seeking food production.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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