Plants that can survive with their roots immersed are called hydrophytes. They can be grown indoors in a vase of water or used to purify the water in freshwater aquariums. A number of common houseplants will grow successfully in pure water without the need for any substrate. These include the popular tropical golden pothos vine and lucky bamboo, as well as more surprising species such as succulent jade plants.
Golden pothos (Scindapsis aureus) will grow roots if a cut stem is placed in tap water. A drop of liquid houseplant fertiliser once a month keeps the leaves dark green and encourages fresh growth. Golden pothos stems rooted in water can be planted in potting compost once they have developed a strong root system.
Lucky bamboo (Dracaena sanderiana) is among the easiest indoor plants to grow in water. Place canes of lucky bamboo in fluoride-free tap water and keep them on a bright windowsill that does not receive direct sunlight. The canes will grow indefinitely without the need for soil or gravel. Add a single drop of liquid houseplant fertiliser once a month and change the water a couple of days later. This allows the roots to absorb nutrients without being damaged by salts.
The umbrella plant (Cyperus alternifolius) is a swamp species from Madagascar that grows well with its roots immersed completely in water. It can reach 1.5 m (5 feet) in height if grown in a large aquarium. Umbrella plants grow best when they are grown in a pot of peaty soil that is sunk into a larger pot full of water.
While they are succulents and prone to root rot if grown in wet soil, jade plants (Crassula ovata) are able to grow in pure water for long periods. A jade plant branch placed in a jar of water grows roots and even new leaves and stems, provided the water does not dry out. Jade plants can be propagated by taking these stems out of water once they have developed roots and potting them up in normal compost.
English ivy (Hedera helix), the dumb cane (Dieffenbachia Spp.) and the Chinese evergreen (Aglaonema modestum) will all grow in a vase of water provided their leaves and shots are not underwater. The wandering Jew (Tradescantia Spp.) and many philodendrons are also hydrophytes.
- Texas A&M University Extension: Plants that will grow in water
- North Dakota State University: Questions on jade plants
- University of Oklahoma Department of Botany & Microbiology: Cyperus alternifolius -- Umbrella plant Cyperaceae
- "Hort.net": Indoor house plants in water
- Tunkalik: ndoor plants for water purification and nitrate reduction in aquariums