Trailing Lobelia

Trailing lobelia (Lobelia erinus), also known as Blue Lobelia or Lobelia for short, belongs to the bellflower family (Campanulaceae) and is originally native to the Cape region of South Africa.

The growth pattern of the Trailing Lobelia is very compact and dense. Both upright and hanging varieties are available, which we usually cultivate as an annual. The upright Lobelia varieties reach heights between 5.90 and 13.77 inches, the hanging variety develop shoots that can be up to a 3.28 feet long.

The leaves of the Lobelia are arranged alternately, lanceolate and about 0.78 to 1.18 inches long. Their color ranges from green to dark green.

Trailing lobelia forms a multitude of small flowers and blooms from May to September. The flowers are zygomorphic, so they consist of two perfectly symmetrical halves. They are usually found in a pronounced shade of blue, but they are also available in purple and with or without a white eye in the middle.

After flowering, small capsule fruits are formed which release seeds as soon as they open.

Although Trailing Lobelia also thrives in partial shade. More sun means more flowers. Hanging Lobelia varieties are best kept in hanging baskets, but can also be used as understory plants. Trailing Labelia that grow upright are better off in the balcony box, in the pot or in the bowl.

You can use commercially available humus-rich potting soil as a substrate for your Lobelia.

The frequent bloomers have a high nutritional requirement, therefore, regular fertilization is a must. Fertilize the Trailing Lobelia every two weeks with a little low-dose composite fertilizer after watering it. Important: Use only fertilizers with a low nitrogen content. Nitrogen promotes plant growth, but at the same time inhibits flower formation.

To have the flowering period last until fall, the Trailing Lobelia is pruned by a third after the first main flowering at the end of July.

Wintering is only possible in very few Trailing Lobelia varieties. The ‘Richardii’ variety, for example, can be placed in a bright winter quarters between 50 and 59 degrees Fahrenheit before the first frosts. When placed there, water it moderately and put it back outside after ice saints. As a rule, however, it makes more sense to collect the seeds in fall and sow the lobelia again next spring.

Numerous cultivars and varieties of the Trailing Lobelia are available in stores. They differ in leaf and flower shape as well as in their growth. Upright and rather small, at a height of around 3.93 inches, are for example:

• “Blue pearl”: bright blue flowers
• “Cambridge Blue”: light blue flowers
• ‘Kaiser Wilhelm’: light green foliage and cornflower blue flowers.
• “Rosamunde”: intense red flowers with white eyes
• “Snowball” and “Regatta White”: pure white
• “Pumila Splendens”: dark blue with white eye

Trailing Lobalia are propagated by sowing. From March, sow the seeds under glass at 60.8 to 64.4 degrees Fahrenheit. Since they are light-dependent germinators, the seeds are only covered with a thin layer of substrate. The seedlings are then picked out in individual groups so that small, compact plants emerge. From May - as soon as the ice saints are over — the plants can move outdoors and to their final place on the balcony, terrace or in the garden.

The above-mentioned lobelia variety “Richardii” can only be propagated using cuttings. Prune it in November.

Note: Trailing lobelia is prone to mold (gray rot). With the right choice of location (nice and airy) and a suitable substrate (low in nitrogen and permeable) you can prevent the fungal disease — however, hundred percent protection cannot be guaranteed. You should therefore regularly check for infestation and remove the affected parts of the plant immediately. There is a high risk of infection, especially in balcony boxes.