21 plants to avoid in the aquarium

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Many new hobbyists have problems keeping plants in their tanks because they've been sold non-aquatic ones. Jeremy Gay explains more.

I can travel the length and breadth of the country and bet that most aquatic shops I visit will be selling non-aquatic plants for use in aquariums. You only have to look into the standard, tiered plant cascade to spot plants in among the Elodea that should actually be in a pot or on a windowsill, rather than under water.

Who’s to blame?

The sources of aquatic plants are mainly larger greenhouse enterprises on mainland Europe, like Holland and Germany, or outdoor plant farms in the Far East, like in Singapore and Malaysia. Such places produce many varieties of aquatic plants — as well as many non-aquatic ones.

The usual sales procedure for most stores is simply to order, say, 250 assorted bunches and within this mix will usually be non-aquatic species. However, these will not last long underwater. They drown, then disintegrate.

They are, however, available in a stunning variety of leaf forms, colours and textures, so that, given the choice, the uninformed aquarist will actually choose non-aquatics over true aquatics because they look more exotic and more colourful.

So where does the blame lie? Plant nurseries may have a legitimate business producing house plants for garden centres, although if they have we could do with them telling the wholesalers and retailers which are good underwater and which are not.

That’s the first problem. The second is that some retailers are either ignorant of plant names and varieties and cannot tell the difference — or they are blatantly aware of what they are selling and just take the money. Nurseries, of course, could be doing the same.

Either way, an aquatic shop which stocks and then sells non-aquatic plants from its plant tank, knowingly or otherwise, probably isn’t the best place to buy plants. If they are prone to the odd fib in the chase for a quick buck, what else aren’t they telling you?

…but most aquatic plants are grown out of the water!

Here lies another twist. Even many of our well-known aquatic plant species, like Amazon swords (Echinodorus spp.), Crypts, (Cryptocoryne spp.) Java ferns (Microsorum spp.) and Anubias (Anubias spp.) are grown out of the water  — known as emerse — in commercial nurseries.

In fact, all the stem, moss and carpeting plants are too, and the only ones that aren’t are true floating plants like Water hyacinth and Water lettuce and true aquatics like Vallisneria, Ceratophyllum and Elodea. So most of our "aquatic" plants only spend some time underwater in the wild, as in the rainy season. For most of the year they just grow on the water’s edge, either with their roots in water or moist soil.

It’s during the dry season that many grow and flower, and nurseries use this adaptive behavior to grow their aquatic plants out of the water where they will grow more quickly in abundant light and CO2 from the atmosphere. They won’t pick up algae or aquatic snails either — and are much easier to propagate that way.

Nurseries will grow plants without any soil, instead just having their roots in water, known as hydroponics. This way only fertilisers are added to the water and the plant has everything it needs.

This then translates to the difference between success and failure when you put plants in your aquarium. To keep them happy and growing underwater — submerse — you must also provide them with enough light, enough CO2 and a constant supply of fertilisers. Get this wrong and species like Glossostigma will last just a short a time underwater, as will the true house plant species mentioned earlier.

How do you identify house plants over aquatic plants? The giveaway is to avoid anything with a variegated leaf, like green and white (as pictured above) or red and green. Next feel them or pick them up. A house plant will stand up in the pot unassisted, but most aquatics will droop when out of water.

The leaves on a non-aquatic will feel shiny or waxy and the leaves themselves may come to a sharp point, as these are actually drip tips for channeling away rainwater! If it looks and feels wrong, it probably is.

Better education

So, all in all, we need better education into what will grow underwater and what won’t. Part of PFK’s job is to inform the consumer about what to buy and what not to buy, so we bought a load of the most commonly stocked non-aquatics and photographed them.

Hopefully you will be able to use the guide below as an ID reference and then make the necessary steps to avoid them.

With regard to better knowledge we can pressure some shops to make the facts clear, but ultimately the owners have to decide themselves to become better informed and therefore give the customer better, honest advice.

It’s a no-brainer that a shop that tells you not to buy a plant because it is non-aquatic will win your future custom, but one that takes your money and fails to be honest, won’t.

Should just anyone sell non-aquatic varieties?

This is the interesting bit and potentially when the stocking and selling of non-aquatics may come full circle, for as well as aquariums there are also growing pet/plant/other aquatic sectors where these plants really come into their own.

Do a quick Google search of the terms paludarium, terrarium, vivarium and even riparium, and your eyes will be opened to a world which caters for life both above and below the water line.

Paludariums, from the word meaning marsh, typically contain one third to one half of water volume and air above. This means you can then have terrestrial (dry land) areas above the water line, along with the flora and fauna that like to inhabit them, as in the picture above.

Many non-aquatics featured here would be perfect planted in soil or coconut fibre, either completely above the water or with their roots in the water below to obtain a constant supply of moisture.

Indeed, the paludarium can offer a whole host of opportunities for fishkeepers as, if they set up one large enough, they can happily keep fish in the bottom and then plants, amphibians and even reptiles in the space above.

Think about it. If you're going to set up an Amazon-themed aquarium what would be more natural than a living canopy growing above? Pretty cool eh? Then, by putting their roots in the water, all those terrestrial house plants will help to purify the water by using the nitrate and phosphates as fertiliser.

There are ever more glass terrariums available, so these are becoming really viable and fashionable as you can have not only the rainforest stream biotope but the rainforest biotope above it.

So, thanks to the growth of paludariums and terrariums and their move into the aquatics market, a switched-on retailer may be knowingly selling house plants but open about doing so because he or she has experienced, knowledgeable customers who own and run those sorts of enclosures.

If checking online, good sellers will label their goods as "terrarium plants" so that everyone is clear when they make a purchase.

21 house plants to watch out for

Dracaena deremensis

Hemigraphis repanda

Cordyline 'Red edge special'

Hemigraphis colorata

Dracaena deramensis var.

Dracaena godseffiana

Cordyline species 'Red Edge'

Acorus gramineus var. variegatus.

Ophiopogon jubaran

Chlorophytum bichetti

Dracaena sanderiana

Syngonium podophyllum

Ophiopogon japonica

Cordyline species 'Compacta'

Spathiphyllum wallisii

Acorus gramineus var. Ogon

Syngonium podophyllum 'Red Knight'

Trichomanes javanicum

Selaginella wildenowii

Cordyline sp.

Acorus gramineus var. pusillus

Good guys will identify and label their plants

We bought all our plants from plantedtanks.co.uk where Tony Newsom-Virr, the proprietor, is one of the good guys as he clearly labels his house plants as terrarium plants.

Incidentally, he says one of the biggest problems when advising customers how to grow plants is that they have inadvertently bought terrarium plants as true aquatics from their local shop.

So the practice of mis-selling is clearly still going on, creating a frustrating headache for new and unsuspecting aquarium owners.