Dwarf Hygro

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 on the US Federal Noxious Weed List: importing it or moving it across state lines without a USDA APHIS permit is prohibited, and many states ban it outright, so it is effectively off the US market. Elsewhere, check your local invasive-species rules first, where it is legal it is a great beginner plant; in the US, choose a legal alternative, and never release it anywhere. (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: Hygrophila polysperma is on the US Federal Noxious Weed List: under 7 CFR 360 it may not be imported or moved interstate without a USDA APHIS permit, and states including California, Florida, Massachusetts, Minnesota, North Carolina, South Carolina and Wisconsin ban it outright. 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 (restricted)

FAQ

Why can't I buy this plant in the US?

It is a federal noxious weed - too invasive. Fragments regrow and clog waterways. Importing it or moving it across state lines without a USDA APHIS permit is illegal, and many states ban sale as well, so US shops cannot stock it.

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.