Flowering Aquarium Plants Part 1

(Unedited version)
Originally appeared in the December 2007 issue of
Tropical Fish Hobbyist Magazine

Most of the plants we grow in our aquariums flower naturally in the wild but it can be a rare instance in your home aquarium. It can be very exciting to find your aquarium plants producing blossoms and some can even be propagated this way. There are a few tips to knowing what plants are most likely to flower and what they need to do so. And what to do with those that can reproduce to achieve the best results.

All flowering plants are called angiosperms. Not all the plants in the aquarium are angiosperms. Mosses, liverworts like riccia and pelia and aquatic ferns like Java fern, Bolbitus and Ceratopteris are more primitive plants and don't produce flowers or seeds but instead create spores giving them the name of sporophytes.

Of course any of the flowering plants that we keep in our aquariums has the potential to flower for us in our homes but some are much more likely to do so than others. There are several aquarium plants that are happy to surprise us with flowers while others may require more coxing. In the next 2 months I'll list a few of the aquatic plants most likely to bloom in the aquarium and the care they'll need in order to optimize the chance that they will.


One of the first aquatic plants to bloom in the aquarium for many people is an Aponogeton crispus. These plants have been very popular in the aquarium hobby for many years. The plants can be variable and crossed with other Aponogeton which has encouraged cultivated forms and hybrids. One of the reasons that Aponogeton have become so popular in the aquarium trade is the ability of the rhizome to withstand a dry period, making it easy to ship these plants. You may even see them hanging in small dry bags in pet sections of larger stores. I've personally had some problems with the bagged rhizomes surviving, but have had success with those I've purchased already sprouting in aquarium stores. The problems I've had with the bagged rhizomes is probably due to my location in the hot dry desert. It seems reasonable that they would easily dry out or get too hot during shipping here. I've heard of many other success stories with the dry bagged Aponogeton rhizomes in other parts of the country.

These plants will usually do better in soft to moderate water and may have troubles in harder water. They will appreciate a rich substrate. In a new aquarium or a tank with a very clean substrate, and no additional nutrients, Aponogeton will probably only last for a few months at best. They will do better with specially prepared aquarium plant substrates, or if you're a do-it-your-selfer, you can use a small layer of potting soil or compost under your gravel. There are many options available and most of them seem to do the job if your consistent in your approach. The addition of CO2 can also be helpful for growing Aponogeton, particularly if you have harder water. The plants will sometimes die down and don't seem to have the longevity of some aquarium plants but many can be kept alive for several years if they are well cared for.

When your Aponogeton flowers you may observe the slim stalk coming up between the leaves, though if you're not looking for it you might not notice. When it breaks the surface of the water you'll probably see it. Initially the flower spike, called an inflorescence is covered by a green spathe, but soon the spike will pop out covered with white, or violet tinted flowers. In A. crispus there is one flower spike, but depending on the species Aponogetons can also have 2 or 3. Some Aponogetons have violet or purple flowers. Sometimes seeds can be produced from Aponogeton flowers. The pollen most be carefully transferred between the flowers with a small brush or cotton swab. If your plant is self fertile then green “berries” will develop and drop into the water. These will float until they open and drop the seed to the bottom of the aquarium where they can grow in to new plants. Fish and other aquarium inhabitants may snack on your seeds. Removing the fish or the seeds to another tank will increase your chance of getting baby plants.

Sword Plants

The sword plants or Echinodorus are another favorite that blooms readily in the aquarium. In fact you can often buy large Amazon “mother” swords with several to many baby swords. These are called adventitious plants and they can sometimes occur while blooming. Like the Aponogetons swords can be hybridized and cultivated and have been.

I've had several sword plants bloom for me. Some of these plants turn brown and die, as soon as any part rises above the water. This is probably once again due to the extreme dry conditions in Arizona. Covered tanks can prevent dryness in plants that grow above the water surface and are generally recommended. I do have other swords seem to be a bit better suited to surviving in more arid climates and will bloom happily and with some regularity. I have one group in my living room that's been blooming regularly for years producing many adventitious babies that have found places to live in other aquariums both here and at the homes of others.

Sword plants require a good healthy substrate to preform their best. In addition to the prepared mixes, or adding special substrates or potting soil, I've also had very nice swords using compressed peat plates under the gravel. Most swords found for sale for the aquarium are very easy to care for in terms of lighting, water pH, and hardness. I've had quite a lot of luck growing many swords in my hard alkaline Arizona water with everything from strong florescent lighting to filtered sunlight.

Swords normally have moderate growth speed but with the addition of CO2 they can grow much more quickly. Most of them can also get quite large and should be placed in an appropriately sized aquarium. A moderate sized sword can easily fill most of a 20 gallon aquarium. A very large sword will have no problem filling a 50.

When your sword plant flowers it will generally send an inflorescence up out of the surface of your tank. If you have an open tank be sure to keep it from getting in to the light where it will be burned. Some sword plants can have a branching inflorescence. I've noticed that even when a plant doesn't generally branch it may if it's damaged in some way during growth, like getting in to the aforementioned aquarium lights. Blossoms develop into small white flowers.

Your sword plants can produce seeds but this can be a somewhat difficult process, fortunately they will often produce adventitious plantlets, or baby plants. I've read that these are more often encouraged if the inflorescence is kept under water. They certainly don't want to grow roots until placed back under the water and it will be best if your plantlets get used to life below the water early on since you'll probably want to move them to another aquarium when they get larger. After the plants have grown several leaves and a good root system than can be removed from the parent plant. I've found that the larger the plant is when removed, within reason, the better chance you have of it surviving and the quicker it will become acclimated to it's new life on it's own.

Sagittaria subulata

Another plant that likes to surprise you with blossoms is the moderately sized grassy Sagittaria subulata. Sometimes mistaken for Vallisneria, Sagittaria is usually smaller and for me at least, grows at a much more reasonable pace than Val which can seemingly take over an entire aquarium overnight. Val may also bloom in the aquarium but in my experience Sagittaria is much more likely too and does so regularly.

S. subulata is an undemanding plant. It usually stays at a medium height making it nice for the midground in smaller or the foreground in larger tanks. Sagittaria seem to do well in most tanks. I've had them grow wonderfully and bloom in aquariums with plain gravel and low light and in the soupy nutrient filled tubs I keep under shade cloth in the Arizona sun. They seem to be quite happy in either extreme. I've been surprised by blossoms in forgotten tanks in the corner of the fishroom.

When flowering, S. subulata sends a long stalk to the surface of the tanks. Small, delicate, white, 3 petal flowers float at the surface of the water. Though, of course, they do seed in the wild it's not practical in the aquarium. Fortunately S. subulata reproduce quite well through runners, so even without seeds you should end up with plenty of extra plants.

Aquarium plant blooms aren't as showy as those you can grow on your house plants or in your front yard garden but it is fun to experience this aspect of the hobby. And even in their small way the blossoms of aquarium plants have their own beauty and appeal.

This month we looked at 3 very easy to grow aquatic plants that will bloom freely in the aquarium. Next month we'll look at a few that take a little more planning in order to watch them bloom, the stemmed plants. And we'll look at a few that take a little more work, showing off their best blossoms in a high tech tank.

Welcome to the Jungle | Into The Forest | The Creepy Crawlies | A Clearing in the Thicket | Algae Eaters for the Planted Aquarium
North American Natives | Why things go wrong Pt 1 | Why things go wrong Pt 2 (Algae) | Algae Eating Shrimp | Lo-Tech Tanks
Welcome to the Fish Room | The Stemmed Plants | Mosses | A Livebearer Biotope | Planted Tank Social | The Genus Hygrophila | Cyanobacteria
Easy Plants | What I Did Last Summer | Decorations in the Planted Tank | Botany-An Introduction to Plant Biology | Botany-Anatomy of a plant
Botany-How Plants Work | Easy Rosettes | Going High-Tech | Floating Plants | Dealing with Success | Bringing the Outside In | Vallisneria
Hair Algae | Flowering Aquarium Plants Part 1 | Flowering Aquarium Plants Part 2 | Liverworts in the Aquarium | Elements of Design
Planted Aquarium Maintenance | More Mosses | Invaders | Ferns in the Aquarium | Setting up a Planted Aquarium
Seaweeds of the Pacific Northwest | Proserpinaca | Hardware for the Planted Aquarium | Rotala | Neocaridina Shrimp | Lo-tech Tank Tips

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