Dwarf Hygro
Dwarf hygro is one of the easiest, fastest stem plants there is - which is exactly the problem.
🗓️ Last reviewed: July 2026
Overview
Dwarf hygro is one of the easiest, fastest stem plants there is - which is exactly the problem. It is so vigorous that it is a US federal noxious weed, banned to buy, sell or transport in the United States. Elsewhere it is a great beginner plant; in the US, choose a legal alternative and never release it. (Hygrophila polysperma.)
Origin & Natural Habitat
Streams and wetlands of the Indian subcontinent and Southeast Asia; now an invasive weed in warm US waterways.
Appearance
Slender stems with pale-green oval leaves; grows fast and roots readily, including from broken fragments.
Why People Grow It - Qualities & Benefits
- Extremely fast and easy (where legal)
- Strong nutrient uptake
- Roots from fragments
- Tolerates low light
Care
Light: Low to high - it grows in almost anything.
Water: 18-30°C, pH 6.0-8.0; very tolerant.
Substrate: Any; roots easily. Grows rooted or floating.
CO₂ & feeding: Not needed; already fast.
Placement: Background (where legally kept).
Extra: ⚠️ In the United States Hygrophila polysperma is a federally listed noxious weed - it is illegal to buy, sell, or move across state lines, because fragments establish and choke waterways. If you are in the US, do not keep it; pick water wisteria or another legal stem plant instead.
Propagation
From any cutting or fragment - which is precisely why it is invasive. Bag and bin trimmings; never flush or dump.
Common Problems & Pests
Its own vigour; legal status in the US. Otherwise nearly unkillable.
Toxicity & Safety
Non-toxic to livestock, but an aggressive invasive - never release aquarium plants into the wild anywhere. Dispose of trimmings in the household bin, sealed and dry.
Best Suited For
- Beginners in regions where it is legal
- Fast nutrient export
- NOT for US keepers (banned)
FAQ
Why can't I buy this plant in the US?
It is a federal noxious weed - too invasive. Fragments regrow and clog waterways. Buying, selling or moving it across state lines is illegal in the United States.
How should I dispose of aquarium plant trimmings?
Never flush them or put them in a pond or waterway. Bag them dry and put them in the household bin - any fragment of a vigorous plant can start an infestation.