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Hardiness: Easy
Light Needs: Medium
Plant Structure: Stem
Family: Lobeliaceae
Genus: Lobelia
Region: North America
Location: Temperate and Subtropical North America
Size: Stem width: 7-15cm (3-6in)
Growth Rate: Medium
Can Be Grown Emersed: Yes


Lobelia cardinalis, sometimes known as 'Cardinal Flower', is a native of the eastern and central United States where it can be found growing in moist soils along streams, ponds, and ditches. In its emersed state, it produces green leaves with purplish undersides and bears attractive scarlet, bell-shaped flowers which make it highly popular among terrestrial gardeners. Submersed growth, in contrast, is bright green. Long popularized by the Dutch, L. cardinalis is a fairly common plant in the trade.

L. cardinalis is fairly easy to grow. Lighting should be at least moderate, although higher lighting will result in more compact, lusher growth. CO2 injection is not necessary, but highly recommended for vigorous growth. Water column fertilization is a large factor in how large this plant can ultimately get. Higher nitrate (10-20ppm), phosphate (1-2ppm), and micronutrient dosing will result in the fastest, lushest growth and the greatest number of side shoots.

This unusual stem plant grows upward at a moderate pace, producing side shoots at a rate that highly depends on growing conditions. It also tends to produce many white roots at the nodes, which will have to be concealed with careful pruning. Pruning should be done by topping and replanting the tops. If a street of this plant is desired, the tops should be cut at progressively shorter intervals.

L. cardinalis has long been used in Dutch planted aquariums in so called Leiden streets because of its moderate growth rate and adjustable height. Its considerable size and unique leaf texture make it an excellent choice for the would be aquarist trying to create a more formal layout.

Photo #1: US and International Copyright 2004 by Svennovitch All Rights Reserved.

Photo #2: US and International Copyright 2004 by Svennovitch All Rights Reserved.