Water lobelia
Lobelia dortmanna · Campanulaceae
The gardener's calendar
Ideal time to plant water lobelia: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Family
- Campanulaceae
- Form
- Submerged aquatic plant
- Foliage
- Persistent, fine and linear
- Flowering
- Summer (July-August)
- Adult size
- 10-30 cm in height
- Hardiness
- Moderate (down to -5°C)
- Origin
- Temperate regions of Northern Europe
- Growth
- Slow to moderate
Care
Watering and submersion
Lobelia dortmanna is an entirely aquatic plant that must remain permanently submerged. Maintain a water depth of 20 to 60 cm depending on lighting conditions. In ponds or aquariums, regularly check that the water remains clear and oxygenated to promote good growth.
Light exposure
This plant thrives in bright conditions, ideally in semi-shaded to partially sunny areas. It will tolerate partial shade but prefers at least a few hours of direct light daily. In aquariums, appropriate lighting (10-12 hours per day) will stimulate its growth and flowering.
Substrate and soil
Plant the lobelia in a rich substrate composed of a mixture of nutritious potting soil and fine sand. Adding nutrients to the soil will promote rooting and stability. Avoid overly compact substrates that would hinder water circulation and root absorption.
Fertilization
Apply a liquid fertilizer specific to aquatic plants once a month during the growing season (spring-summer). A supplement of micronutrient iron can improve foliage color. Reduce applications in autumn and suspend them in winter.
Pruning and trimming
Pruning is generally not necessary. Simply remove dead or damaged leaves over time. In aquariums, lightly trim the stems if they become too invasive to maintain harmony in your aquascape composition.
Pests and diseases
This aquatic plant is generally robust. Watch for filamentous algae that could compete with it. Good water quality and adequate filtration prevent most problems. Occasional aquatic snails do not pose a major threat.
Did you know?
Lobelia dortmanna takes its common name from the Dortmund region in Germany, where it was discovered and studied in the nineteenth century. This rare aquatic plant is adapted to fully submerged life and produces its delicate blue or violet flowers only during periods of active growth, making it a discreet yet remarkable star among passionate aquascapers.
Where to buy it
Best planted in spring or autumn, away from frost and heatwaves. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September, October.
Add this plant to my garden →Plants from the same family
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Tips generated and checked by Viridia — adapt them to your local climate.