Growing plants in water, known as hydroculture or passive hydroponics, is an accessible way to cultivate houseplants indoors without the mess of soil. This technique involves submerging the plant’s roots in a water reservoir, allowing the plant to absorb what it needs directly. The resulting clean, elegant display can thrive indefinitely with the right initial setup and consistent care. Eliminating soil minimizes the risk of common issues like fungus gnats and overwatering, making indoor gardening simpler for many enthusiasts.
Plants That Thrive in Water
Many popular houseplants are excellent candidates for long-term water growth, thriving by developing specialized “water roots” that differ structurally from soil roots. The vining aroids, such as Pothos (Epipremnum aureum) and Heartleaf Philodendron (Philodendron hederaceum), are arguably the easiest to transition and maintain in a water-only environment. Larger-leafed tropicals like Monstera deliciosa and Chinese Evergreen (Aglaonema) also adapt well, offering lush foliage with minimal effort. The popular Lucky Bamboo (Dracaena sanderiana) is one of the few plants naturally suited to a permanent water environment.
Culinary herbs with soft stems, like Mint, Basil, and Oregano, root quickly in water, providing a convenient, small-scale kitchen harvest. They are often best maintained by consistently harvesting the new growth, though they may require more frequent nutrient replenishment than slower-growing houseplants. Woody herbs such as Rosemary and Sage can also be rooted in water, but they develop stronger, healthier plants when transferred to soil after roots are established.
Kitchen vegetable scraps offer a simple, short-term project, though they rarely produce a full harvest in water. Green onions and leek bases, placed root-side down in a shallow glass, will rapidly regrow their green tops for multiple small harvests. Similarly, the base of a head of Romaine lettuce or celery, submerged slightly, will sprout new leaves, making a decorative centerpiece that provides a temporary yield of fresh greens.
Initial Setup for Hydroculture
The first step in setting up a water-grown plant is selecting the appropriate vessel, which plays a large role in preventing common problems. While clear glass containers allow for easy visual monitoring of root growth and water level, they also permit light penetration, which encourages algae growth. Using an opaque container, or covering a clear container with dark material like foil or paint, is highly recommended for long-term setups to block light from reaching the water and roots. Roots are naturally negatively phototropic, meaning they prefer to grow away from light, which promotes healthier development.
Preparing the water is as important as preparing the cutting itself. Tap water often contains chlorine or chloramine, which can be detrimental to delicate new roots, so it should be allowed to sit out in an open container for 24 hours to dissipate. When taking a cutting, use a clean, sharp blade to make a cut just below a node, which is the small bump on the stem where a leaf or aerial root emerges. Removing all leaves that would sit below the water line is necessary to prevent them from rotting and fouling the water before new roots can form.
Once the cutting is prepared and placed in the vessel, the setup should be positioned in an area that receives bright, indirect light. Direct, intense sunlight can overheat the water, which reduces the dissolved oxygen content and stresses the new roots, potentially leading to rot. The water level should be high enough to fully submerge the nodes but should not cover any remaining foliage.
Maintaining Water-Grown Plants
Long-term survival in hydroculture requires regular water changes to maintain a healthy environment for the roots. The frequency of a full water change is ideally every two to three weeks, though smaller vessels may require it more often. This process is necessary because plants constantly consume dissolved oxygen for root respiration, and stagnant water quickly becomes deoxygenated and toxic. A full flush also removes metabolic waste products and accumulated mineral salts.
Water alone lacks the necessary macro and micronutrients for sustained plant growth, so a complete liquid fertilizer must be added for long-term health. A standard hydroponic nutrient solution is best, but a highly diluted version of a regular houseplant fertilizer can also work. The dosage should be significantly lower than the manufacturer’s recommendation for soil, often reduced to one-quarter or one-eighth strength, and should only be added when the water is changed.
Two common issues in hydroculture are algae growth and root rot. Algae, which appears as a green film, is primarily caused by light exposure and consumes nutrients meant for the plant. If algae appears, the vessel must be thoroughly scrubbed, the water changed immediately, and light penetration reduced. Root rot is characterized by roots becoming brown, slimy, and foul-smelling, often due to low oxygen levels. If root rot is severe, the infected roots should be trimmed with sterilized scissors and the remaining healthy roots can be briefly soaked in a diluted hydrogen peroxide solution (a 1:1 mixture of 3% hydrogen peroxide and water) before being placed into fresh, clean water.