Cryptocoryne cordata var. blassii originates from swamplands in southern Thailand, Malaysia and on the island of Borneo. It is the most popular variety of C. cordata and very easy in cultivation.
This Cryptocoryne is an undemanding slow grower. It needs low to medium light (0.25-0.5 watts per litre), as its natural habitat is in shaded rivers. It does not require additional CO2, however, CO2 fertilisation may have a positive effect on growth. It can be kept in hard water very well. In order to reach its full height it needs a substrate rich in nutrients.
The emersed cultivation of C. cordata var. blassii is easy. It only needs low light and should be sprayed with water from time to time in order to increase the humidity. It also needs a nutrient-rich substrate when cultivated above the waterline.
In the aquarium, this plant can reach a height of about 20 cm in time, given that it grows in a nutrient-rich substrate. Cut off yellowish or decomposing leaves with a sharp pair of scissors.
Its singular leaf form and greenish red coloured leaves as well as the dark red leaf undersides make it an excellent choice for the middleground of an aquarium. In Dutch aquaria this plant lends itself to making "streets".
<a href="http://www.flowgrow.de/db/aquaticplants/cryptocoryne-cordata-var-siamensis" target="_blank"><img alt="Cryptocoryne cordata var. siamensis" title="Cryptocoryne cordata var. siamensis" src="http://www.flowgrow.de/db/widget/aquaticplants/cryptocoryne-cordata-var-siamensis" /></a>
[widget=aquaticplants/cryptocoryne-cordata-var-siamensis]Cryptocoryne cordata var. siamensis[/widget]