Anubias Question

[Golden Rams]

Is it true you can grow anubias out of water as long as the rhizome is submerged?

[Cory]

Not really. It doesn't matter if the rhizome is submerged. It's the overall humidity. You can grow them in dirt if the air is humid enough in the enclosure.

[Expectorating_Aubergine]

Pretty much what Cory said. They make great terrarium plants if the humidity is high. I currently have a 90 gal cube stuffed to the gills with anubias. The tank is only 1/3 full, so the leaves are above water for the most part. They grow way faster in my experience emersed. You can also feed them heavier that way too. 

[gardenman]

Humidity is the key. If you poke around on YouTube you can find tours of the Tropica and Dennerle greenhouses where they grow their plants emersed. It's pretty impressive stuff. They have high humidity in the greenhouses and for plants that want even more they have plastic tents they'll put over those plants. If you've got enough humidity, you don't need much water.