Germinating Lobelia

Chilean Lobelia species are relatively easy to germinate. They do not need cold stratification, and germinate realtively quickly. Lobelia bridgesii, Lobelia excelsa, Lobelia polyphylla, Lobelia tupa are very similar in their germination behaviour.

In literature the following procedure is mentionned for Lobelia bridgesii: sow over humid humus surface, cover with 2 mm. of humus and 5 mm. of sand, and germination starts from 10 to 75 days after sowing.

We prefer to sow superficially, not covering the seeds, and we obtained good results, without exposing the seeds to direct sunlight, and keeping them initially at lower temperatures (10-15 C). Although cold stratification is not required, we have not run specific tests, but it is possible that higher temperatures may make germination more difficult, especially for the northern desert species (Lobelia excelsa, Lobelia polyphylla).

The substrate for Lobelia bridgesii and for Lobelia oligophylla should be rich (high humus content), somewhat acid, while the substrate for other Lobelias (Lobelia tupa, Lobelia excelsa, Lobelia polyphylla) should be relatively poor, with about 50% sand.

Lobelia oligophylla is somewhat different in the sense that it grows on very wet soil, on the borders of swamps or inundated areas. It germinates faster (after 7 days) than other Lobelia species, and it needs constant humidity.