Onion Plant

Message Board / Forum Goldfish Plants Aprils Plants Of The Month Are...

Posted by: emmahj Apr 6 2004, 01:42 PM
Well, despite the computer losing the original version of this article and me having to re-write the whole thing again - hence the slight delay, grrrr - here are Aprils Plants of the Month.

This month, were looking at real specimen plants for the tank rather than the usual fill a gap type plants Both of the below species need lots of room to really show what they can do, so if you only have a teeny 10-gallon, sorry about that But well be looking at the little guys of the aquatic plant world in May.

Here are the stars of the show:

Onion Plant (Crinum)

Good old Onion Plant, the mainstay of many a goldfish owner's tank Despite its name, Onion Plant actually belongs to the Lily family and in an open-topped tank it will eventually produce a beautiful, aromatic lily flower on the surface. Keen gardeners will also recognise the Latin name as many species of Crinum grace our flower beds. In Thailand, its country of origin, the bulb is used in a cream to soften the skin and the flower as a perfume. Mm

Generally undemanding and distasteful to herbivorous fish due to its tough leaves, Onion Plant only needs one thing: plenty of space This is definitely not a plant for tiny tanks, as it can grow over 2m tall. 1 metre is more usual however.

There are three varieties: Crinum thiainum, Crinum natans and Crinum calamistrum. Of these, thiainum and natans are the easiest to grow, requiring very little in the way of light, water conditions or maintenance. Thiainum has long, smooth, rich green leaves, whereas natans has shorter, darker green and slightly rippled leaves. Calamistrum however needs high to very high light, but repays this extra need with very narrow, dark green and spectacularly rippled leaves, which almost look as if they were made from corrugated green paper, so deeply are they crimped. Calamistrum can also be grown in brackish tanks, though in fact none of the Crinum family mind a low level of salt.

Summary of care:

Care Level: very easy (medium for calamistrum)
Availability: thiainum and natans are commonly available but calamistrum is harder to find.
Cost: varies depending on availability but usually not expensive.
Max height: 200 cm (calamistrum only grows to 120 cm)
Max width: 20-30 cm
Growth: slow to medium
Goldfish Edibility Rating: highly distasteful, rarely even nibbled at.


Light level: low, medium or high for natans, medium to high for thiainum and high to very high for calamistrum.
Temperature: 18-28 C (no cooler than 18 C though)
pH: 5.5 - 8
Hardness: very soft - hard
Nutrients: not required, but will certainly appreciate some added fertiliser
CO2: not required but does respond to added CO2
Water movement: does not mind current or splashing (in fact leaves look very striking swaying in a current)
Planting: Onion plant grows from a bulb which must be planted in the substrate so that the top 2/3rds of the bulb is visible, otherwise it will rot.
Maintenance: none, except to prune back any leaves which get too long (remove from the bottom rather than cutting at the top).

Mexican Oak Leaf (Shinnersia rivularis)

This is truly a plant of many names It is variously called (and honestly I'm not making this up) Acorn Hygro, Water Oak, Sombrero Fern, Loop Leafed Rotala, Fajita Plant, Yucatan Hygro, Acapulco Rose or Acorn Val. Why? Because the plant really does look like it has oak leaves broad, lobed and a rich intense green - and of course its country of orig high. Growth may become leggy and weak in inadequate light.
Temperature: 18-30 C
pH: 5.5 - 8.5 (prefers acid to neutral)
Hardness: soft - hard (prefers soft)
Nutrients: not required, but will certainly appreciate some added fertiliser
CO2: not required but does respond very well to added CO2
Water movement: does not mind some current or splashing
Planting: plant directly into substrate in bunches; it will quickly take root.
Maintenance: pinch the tops out to encourage bushiness. Prune back if leaves become too dense and block out light to lower leaves.
Propagation: take cuttings and plant into substrate will root freely.
Ponds: Likes a rich pond environment but do not plant over 1m deep.

Other notes: leaves can sometimes become lanceolate (long and thin) rather than deeply lobed. There is nothing that can be done about this, but the effect is not unpleasant.

This is an especially good specimen of Onion Plant (thiainum).

Posted by: Black oranda Apr 8 2004, 02:18 PM
some one just made me want to get an onion plant.
You give so mutch great info emma,thank you
so mutch for the info.

I never knew that they grew to be 2 m long.Wow

Posted by: Ranchugirl Apr 9 2004, 06:19 PM
Emma, I like the Mexican Oak Leaf. Its a stunning plant to grow in a pond...Now, lets go on the hunt for one.
BTW, the "goldfish edibility rating is too cool.

Posted by: Sidekick and Slim Apr 15 2004, 10:00 PM
How does the onion plant reproduce? Will is sprout bulbs from its roots? How does that work?

Posted by: emmahj Apr 16 2004, 02:15 PM
Those pics are good Valkyrie. I like calamistrum best, I must admit. At the moment I have Thiainum growing... and boy, is it growing. lol

Yes, older plants will put forth new bulbs, which you can detach and plant. That's the easiest way of propagating them.