Water plants are an interesting and unique addition to any indoor or outdoor setting. They are hugely beneficial to their aquatic environments, they help to purify the surrounding air, they are generally low-maintenance, and they are simply beautiful to look at.
If you fancy trying your hand at some underwater gardening, our ultimate guide to 19 of the best indoor and outdoor aquatic plants will certainly wet your appetite for water-loving flora!
What are Aquatic Plants?
Aquatic plants, also known as hydrophytes, are plants that have adapted to growing and flourishing in either freshwater or saltwater. They can grow fully or partially submerged in a body of water, or in a substrate that is consistently saturated with water.
Aside from looking pretty, water plants offer many benefits to aquatic ecosystems, they help to oxygenate the water through the process of photosynthesis, they provide food and shelter for aquatic creatures, and some aquatic plants even help to keep the water clean by absorbing pollutants.
Types of Aquatic Plant
There are three main types of aquatic plants;
- Submerged – Submerged aquatic plants are completely immersed within the body of water. Their root system can be attached to the substrate at the bottom, or they may not have any root system at all. Submerged plants are generally the best oxygenators.
- Emergent – Emergent aquatic plants are usually rooted to the substrate and are mostly submerged underwater, with just a few parts of the plant piercing the surface to access oxygen.
- Free-Floating – Floating aquatic plants have leaves or flowers which always remain above the water’s surface. Beneath the surface, their root systems are usually completely unattached to any substrate.
Indoors – Aquariums
The most impressive way to display water plants indoors is in an aquarium, creating a living, breathing showpiece where plants are used to replicate the enchanting natural habitats of tropical fish.
Aquariums have been found to have numerous benefits for the people who interact with them. Building and maintaining an aquarium is a therapeutic, relaxing, and creative hobby. Gazing at an aquarium is proven to reduce stress levels since its occupants induce a sense of calm as they travel around the tank.
Scientific studies have even found that subjects who spent time watching a fish tank experienced reductions in their heart rate and blood pressure!
The plants and fish have an intricate, symbiotic relationship known as aquaponics, with both playing an important role in maintaining a stable and thriving underwater ecosystem. Aquatic plants reduce your maintenance workload since they help to clean and purify the water and prevent algal growth, helping stabilise pH levels in the water.
The plants provide food and shelter for the fish and also generate oxygen for fish to breathe, whilst the fish exhale carbon dioxide and produce debris which the plants need for healthy growth nutrition. It can take several weeks to achieve this precise biological balance when first setting up an aquarium, so be patient, and be prepared for a little trial and error.
You should allow the plants to establish themselves in the tank for at least six weeks before adding any fish. With thorough research, mindful planning, and appropriate maintenance, aquarium plants can thrive for many years.
If keeping fish doesn’t sound like your thing, you can still create a stunning planted aquarium. Many aquarists create aquascapes purely for the beauty of the plants, and it’s a hobby that has gained increasing popularity since the 1930s.
Aquascaping involves crafting underwater gardens using plants, substrate, and other decorative features, without the introduction of fish. There are even aquascaping contests that showcase the most flamboyant, intricate, and enchanting underwater designs.
Fish-less aquariums are slightly more high-maintenance though. Algae can accumulate quickly if there are no fish to feed on it and keep it at bay, and it can be trickier to stabilise and maintain a balanced ecosystem without the symbiotic relationship between plants and fish.
Caring for Aquarium Plants
If keeping fish with your water plants, you should research which plants are best suited to your fish to ensure a harmonious habitat for all of the occupants of the aquarium.
Aquarium plants can be purchased in pots, but these are unsightly and can restrict growth, so it’s best to remove them from the pot and plant them directly into the substrate. You will need to select a specialist aquarium-safe substrate for any rooted plants.
Before planting anything, consider the size and growth habits of each plant. Aquarium plants are generally split into three categories; foreground; mid-ground; and background. You should place smaller carpeting plants in the foreground where they will be clearly visible.
Position plants by size incrementally, with medium-sized plants in the mid-ground and the largest, most vigorous plants in the background to create a sense of natural depth. Unruly plants will need regular pruning to stop them from taking over the aquarium.
Water plants receive much less sunlight than their terrestrial counterparts so you should invest in a good quality LED light to sit above the water. Aquatic plants usually require between eight and twelve hours of light per day to thrive.
Aquarium plants gain many of the nutrients they need from the substrate and the bacterial balance created by the fish, however, you may need to add extra fertiliser periodically to promote healthy growth. These are available in either liquid or tablet form and are specially formulated to be safe for the fish.
Depending on your water source, you may need to use a water conditioner to achieve an appropriate pH level in the water. A pH level of between 6.5 & 7.5 should be sufficient for both fish and plants to exist happily. The pH level should be monitored regularly.
Best Indoor Aquarium Plants
Amazon Sword is one of the most popular aquarium plants because of its tolerance of a variety of water temperatures and substrates. Its tall sword-like leaves stretch upwards, often reaching the top of the tank, so they are best positioned in the background.
Dwarf Baby Tears is a low-maintenance, carpeting plant with tiny densely packed leaves which provide an excellent home for young fish. They can be rooted in driftwood decorations or directly into the substrate.
Hornwort is a low-maintenance aquarium plant with fine, wispy green foliage of a bright, almost lime green hue. It can be rooted in the substrate or left to float, meaning it’s a versatile choice for creative aquascape designs. Hornwort is fast-growing, so may need an occasional prune.
Java Fern is a great mid-ground leafy plant, which grows best when attached to rocks, gravel, or driftwood. Java fern has a slow growth habit, making it very low maintenance.
Java Moss is a sprawling, carpet-like water plant that provides plenty of ground cover, so is best positioned in the foreground. It’s an excellent food source for juvenile fish and helps to replicate a lush natural aquatic environment.
Marimo Balls are a truly unique water plant that will rest on the bottom of your tank. They look like small green fuzz-covered balls and their distinctive appearance will add a touch of playfulness to any aquarium.
Water Wisteria is a lush, bushy plant that is best suited to the background of an aquarium. It is a great oxygenator and also provides plenty of shelter for fish. It is hardy and requires very little maintenance aside from an occasional prune to keep it from becoming overgrown.
Outdoors – Ponds
Ponds are the natural choice when it comes to incorporating aquatic plants in your outdoor space. Water not only brings a sense of peace and tranquility to the garden, but it also brings immense ecological benefits.
These benefits are further maximised with the growth of aquatic plants, which provide food, shelter, and breeding grounds, not only for fish but many other aquatic and semi-aquatic animals too. Pond plants can encourage wildlife such as frogs, dragonflies, and even newts to visit your garden, whilst enhancing the natural beauty of your outdoor space.
Pond maintenance is also greatly reduced with the introduction of aquatic plants since they remove excess nutrients and impurities from the water, keeping algae at bay, essentially doing most of the dirty work for you!
When planting out your pond, opt for a mix of submerged, marginal, and floating plants to create a diverse habitat. Surface-dwelling pond plants float atop the water creating shade for the fishes and helping to keep algae by minimising light levels.
Submerged plants are great oxygenators and offer a safe habitat for fish and other aquatic creatures to live and breed. Marginal plants are semi-aquatic, flourishing in the consistently wet soil at the edges of a pond, and providing shelter for mammals and insects.
Remember to opt for native plants in and around your pond, so as not to disrupt the existing ecosystem. Our native aquatic wildlife has evolved for millennia to live symbiotically with our native aquatic plants.
Caring for Pond Plants
Pond plants tend to be rather low-maintenance compared to terrestrial garden plants. You should remove any decaying plant matter from the water periodically using a net. During the summer, when the plants are growing most vigorously, you may need to prune any unruly plants to stop the pond become overgrown.
The type of pond plants you choose will dictate their planting method. Some plants can be positioned directly into the substrate at the bottom of the pond, whilst others will need to be planted in baskets that float or are fixed in the water. Marginal plants can be positioned in the same way as terrestrial plants in the wet soil around the edges of the pond.
As with all outdoor plants, temperature considerations will need to be made during extreme weather. Hardier plants can be sunk to the bottom of the pond over winter to protect them from the frost, whilst more fragile plants may need to be stored indoors in tubs of distilled water.
Native perennial water plants should withstand the winter by becoming dormant and returning to bloom as normal in the spring.
Best Outdoor Pond Plants
Duckweed is a free-floating cover plant that provides plenty of shade with its delicate green foliage, preventing algal blooms. It also provides plenty of nutrients for fish to feed on, but can spread quickly if left unchecked. Opinion on Duckweed is divided among pond enthusiasts, but there’s no denying it has a beautiful, naturalistic look.
Horsetail Reed is one of the oldest lifeforms on planet Earth. This prehistoric water plant has dramatic, architectural spiked stems that are adorned with protruding foliage. It can be positioned in a basket or as a marginal plant.
Purple Loosestrife is a marginal plant with dramatic, spear-shaped purple blooms. Being a native wildflower, it is very low maintenance and attracts plenty of native insects and pollinators.
Water Lilies are possibly the best known and most beloved of all pond plants. Also known as ‘aquatic jewels’, they are instantly recognisable for their broad lily-pad foliage and distinctive, showy blooms, bringing an essence of elegance to any garden pond. There are many varieties of Water Lily to choose from, ranging in colour, size, and hardiness.
Water Mint is a marginal aquatic herb plant whose foliage can be used to flavour food and drink. In the summer it displays attractive lilac blooms which attract plenty of wildlife.
Water Violet is a submerged pond plant with cheerful white and yellow blooms which emerge proudly from the water’s surface. Dragonflies and Damselflies love to lay their eggs in the emergent flowers of Water Violet.
Water Soldiers make a fascinating, animated addition to any pond. They are floating plants that travel from the bottom to the surface of the water in spring so that their flowers can take in oxygen. After flowering, they return to the bottom of the pond.
Indoors – Houseplants
If you want to have a go at some aquatic gardening but aren’t ready to commit to something as large as a pond or as demanding as an aquarium, many houseplants can successfully adapt to being grown hydroponically and are surprisingly low maintenance!
Growing houseplants in water is often used as a method of propagation, but some plants will thrive if left in the water, creating a unique and beautiful feature, as the usually concealed roots are exposed in the container. Water-grown houseplants also have the added benefit of helping to purify the air inside your home, just as terrestrial plants do.
When keeping plants in water, you should refresh the water every two to three weeks to keep it clean. You may also need to feed them more regularly using liquid fertiliser to substitute the nutrients they would normally receive from the soil.
Best Indoor Water Plants
Begonias are a diverse genus of flowering plants, often with thick, woody stems and ornate foliage. Many of the varieties that we grow in soil in our homes will flourish when grown in water.
Lucky Bamboo will easily adapt to being grown in water, although you may need to add some gravel to balance the heavy stems. It is thought to attract positive energy and good fortune into your home, and its elegant spiral-shaped stems make it simply stunning to look at.
Philodendron can adapt brilliantly to being grown in water. They will need plenty of bright, indirect light, but are known for their extremely forgiving temperament, making them the perfect choice for beginners.
Pothos are a firm favourite amongst houseplant enthusiasts with their glossy, heart-shaped foliage and trailing vines. They can survive just as happily in water as they can in soil, and are a great air purifier too!
Spider Plants are well known for their fast-growing long, spindly, foliage which is striped with slivers of green and white. They often produce baby plants, known as ‘spiderettes’ which can be removed from the mother plant with the juvenile roots intact and submerged in water.
How easy are water plants to care for?
Water plant care levels vary depending on the plant and its environment. In general, water plants are lower maintenance than terrestrial plants, since they maintain a more self-sufficient and stable ecosystem. They tend to be slower growing than terrestrial plants so are a great choice if you don’t want to spend lots of time pruning.
Is it easy to set up a pond or aquarium?
Setting up an aquarium can be as simple or as difficult as you like. If it’s your first time working with water plants, opt for low-maintenance plants and a simple setup. As you become more skilled at maintaining your plants, you will be able to incorporate more intricate features and more demanding plants.
Ponds can be physically demanding to set up since they often require significant groundwork. However, once plants are established, they are fairly self-sustaining and self-cleaning, minimising your workload.
Where can I buy water plants?
Most garden centres and nurseries will have water plants available, as will aquatic specialist pet stores. There are also many online retailers which specialise in aquatic plant supplies.
Water plants are a great way to add a whole new dimension to your home and garden. Caring for water plants improves our mental health, reduces stress, and offers more scope for creativity than terrestrial planting.
Underwater gardening is something everyone can try their hand at, whether you opt for a simple floating houseplant or a dramatic underwater aquascape, aquatic plants are sure to saturate your home and garden with their unique beauty!