How to Grow Hao
Hao
Limnophila aromatica
herbHao is an aromatic aquatic herb native to Southeast Asia, commonly used in Vietnamese and Southeast Asian cuisines. It features delicate, feathery green foliage and produces tiny purple or pink flowers. The plant has a distinctive lemon-mint aroma and is typically grown in water or wet conditions.
When should you plant Hao in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Hao timeline · Pittsburgh, PA (Zone 6b)
-
Plant Hao
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
Harvest Hao
Around May 17≈ 30 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Hao dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in tropical and subtropical zones 10-11; can be grown as annual in cooler zones
Sign up free to see if Hao grows in your zone — and get a personalized planting timeline.
Get my Hao timeline →Growth Stages
Propagation/Rooting
1-2 weeksTender stem cuttings or seeds begin developing roots; minimal leaf development initially
Keep water temperature 70-78°F; use rooting hormone for cuttings; maintain high humidity and consistent moisture
Vegetative Growth
2-4 weeksPlant develops dense, feathery green foliage; stems elongate and new shoots emerge; plant becomes fuller
Provide bright light and balanced aquatic fertilizer; thin stems if overcrowded; maintain 72-80°F water temperature
Leaf Development
2-3 weeksFoliage becomes denser and more aromatic; plant reaches harvestable size with well-developed leaves
Begin light harvesting of outer stems; continue fertilizing; remove any yellowing leaves
Flowering
4-8 weeksDelicate purple, pink, or white flowers appear on stem tips; plant continues to produce new leaves
Flowering is optional for culinary use; pinch off flowers to encourage leaf production or allow to flower for ornamental value
Harvest
Ongoing, 2-3 weeks between harvestsPlant is fully developed with abundant harvestable leaves and stems; plant continues to regrow after cutting
Harvest regularly from top to encourage bushier growth; can harvest 30-40% of plant at once without harming growth
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
Remove by hand; limit population with snail traps or careful aquatic management; introduce snail-eating fish if in aquarium
-
Reduce excess nutrients; maintain water circulation; provide shaded periods; use algae scrapers; introduce algae-eating fish or shrimp
-
Spray with neem oil or insecticidal soap; quarantine affected plants; remove with soft cloth and water spray
-
Ensure adequate water circulation and aeration; use well-draining substrate; treat with fungicide if severe; improve drainage
Uses
Vietnamese Cuisine & Fresh Herbs
CulinaryHao is essential in Vietnamese cooking, used fresh in summer rolls, pho, salads, and herb platters. The lemon-mint flavor adds aromatic complexity to soups, curries, and stir-fries across Southeast Asian cuisines. [source]
Traditional Digestive & Aromatic Remedy
MedicinalUsed in traditional Southeast Asian folk medicine to support digestion and reduce bloating. The aromatic compounds are believed to have antiseptic and anti-inflammatory properties. [source]
Aquarium & Water Garden Decoration
HouseholdPrized ornamental aquatic plant in freshwater aquariums and water gardens, valued for its delicate feathery green foliage and aesthetic appeal. Easy to maintain and propagates readily. [source]
Fragrant Herb Bundles & Aromatics
CraftDried or fresh hao stems can be bundled and used as natural air fresheners or added to potpourri for its distinctive lemon-mint scent. [source]
Aquatic Ecosystem Support
WildlifeProvides habitat and oxygen production in aquariums and water gardens while serving as food source for aquatic insects and small fish. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Begin harvesting once plant reaches 4-6 inches tall (typically 4-6 weeks after planting). Pinch or cut the top 2-3 inches of stems and leaves regularly to encourage branching and bushier growth. Harvest in morning for best flavor and aroma. Can be harvested continuously throughout growing season. Use fresh leaves immediately after cutting for strongest flavor.
Fun Facts
- 🌱 Hao is also known as 'red stem plant' or 'marsh plant' and is sometimes called 'Vietnamese herb' in English-speaking regions, though this is less common in Southeast Asia where it's simply known as hao (红草).
- 🌱 The plant's name 'hao' (蒿) in Chinese refers to several aromatic mugwort species, and Limnophila aromatica is sometimes called 'water hao' to distinguish it from terrestrial varieties.
- 🌱 Hao propagates so easily from cuttings that a single plant can supply an entire season's worth of fresh herb harvests; it's one of the easiest aquatic herbs to grow for home gardens.
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Hao planting timeline
Tell us your zip code and we'll calculate exactly when to start Hao seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Hao timeline →