Water Lobelia

lobelia dortmanna

Also known as: ["Water Lobelia","Cornish Lobelia"]

Family: Campanulaceae Genus: Lobelia Category: Flowers

Overview

A perennial aquatic or semi-aquatic herb native to Europe, characterized by its blue or violet flowers and adaptation to acidic, nutrient-poor waters.

Benefits & Perks

["wildlife attractant (bees, butterflies, birds)","rare/collector’s item"]

Botanical Classification

Phylum: Magnoliophyta
Class: Magnoliopsida
Order: Asterales
Family: Campanulaceae
Genus: Lobelia
Botanical Name: Lobelia dortmanna

Plant Characteristics

Basic Information
  • Category: Flowers
  • Suitable Location: moist, shaded garden bed or container near water features
  • Suitable For:
    Collectors & Enthusiasts Wildlife Supporters
  • Is Weed: No
  • Allergenicity: low
Environmental Needs
  • Climate: {"temperatureRange":"5–25°C"}
  • Hardiness: {"zones":"6–8"}
  • Misting: rarely required, only if ambient humidity is very low
  • Drainage: Well-draining but moisture-retentive.
  • Soil Type: Moist, acidic, well-draining soil with high organic matter, such as a peat-based mix.
Maintenance Level
  • Maintenance Level: very high
  • Toughness Level: very low
  • Pruning Frequency: After flowering or every 2–3 months to keep the plant tidy.
  • Pruning Intensity: Light to moderate, focusing on deadheading and shaping.
Care Details

Ideal Sunlight Coverage:
Bright indirect light for 6–8 hours daily. Tolerates partial shade, especially in hot climates.

Sunlight Tolerance Tips:
Acclimate gradually to brighter light; protect from direct sun to prevent leaf burn; adjust placement based on seasonal light intensity.

Warning Signs: Yellowing leaves (often due to alkaline soil or overwatering); wilting despite moist soil (root rot).

Care Requirements

Care Difficulty
expert only

moderate

Sunlight

partial shade to full shade

Avoid direct sunlight; rotate plant for even growth; provide dappled light in summer.

Watering

every 7–10 days, allowing soil to dry slightly between waterings

Maintain consistent moisture; avoid waterlogging; use distilled or rainwater due to sensitivity to hard water.

Soil

acidic, peaty, well-drained soil

pH: Acidic, ideally between 5.0 and 6.5.

Use acidic soil mix; ensure good drainage; maintain consistent moisture.

Temperature

Prefers cool temperatures, ideally 50–65°F (10–18°C). Avoids extreme heat and frost.

Keep away from drafts; maintain stable cool temperatures; protect from sudden temperature drops.

Fertilizing

every 4–6 weeks during active growth with a balanced liquid fertilizer diluted to half strength

Dilute fertilizer to half strength; fertilize only when actively growing; flush soil occasionally to prevent salt buildup.

Propagation

Methods

Stem cuttings or division of clumps.

Step-by-Step Propagation Guide
  1. Take 3–4 inch cuttings.
  2. Remove lower leaves.
  3. Dip in rooting hormone (optional).
  4. Plant in medium.
  5. Maintain humidity.

Best Time: Spring or early summer when the plant is actively growing.

Environment

High humidity, indirect light, and consistent temperatures around 60–65°F (15–18°C).

Medium

Peat-based mix with perlite for good drainage and moisture retention.

Hormone

Optional, but can help with root initiation.

Timeline

Roots develop in 3–6 weeks; new growth appears in 2–3 months.

Tools Needed

Pruning shears, rooting hormone, peat-based mix, plastic bag or propagator.

Quick Tips

Use healthy, non-flowering stems; keep consistently moist; provide bottom heat if possible.

Pruning & Repotting

Pruning Guide
Method

Snip off faded flowers just above a leaf node; trim leggy stems to encourage bushiness.

Pruning Plan

Remove spent flowers to encourage reblooming and maintain a compact shape.

Tools

Clean, sharp pruning shears or scissors.

Checklist

Remove dead flowers; trim leggy growth; sanitize tools after use.

Repotting Guide
Best Season

Early spring before the active growing season begins.

Pot Size

One size up from the current pot; ensure good drainage holes.

Method

Gently remove the plant; trim any dead roots; repot in fresh, well-draining soil with a slightly larger pot.

Suggestions

Repot every 2–3 years or when the plant becomes root-bound. Lobelia prefers slightly crowded roots.

Checklist

Check root health; use fresh soil; ensure proper drainage; avoid overpotting.

Advanced Care Tips

Watering Mastery
Watering Checklist

Check soil moisture; use soft water; water early morning; ensure drainage.

How to Apply Water Properly

Water thoroughly until it drains from the bottom, ensuring even moisture distribution without saturating the soil. Water in the morning to allow foliage to dry.

Pro Tip: Use a watering can with a fine nozzle to avoid disturbing delicate roots.
Watering Schedule Tips

Water consistently, allowing the top inch of soil to dry out between waterings. Reduce frequency in winter to prevent root rot.

Soil Improvement

Add peat moss or compost for acidity and moisture retention; mix in perlite for drainage.

Temperature Stress Management
Signs of Temperature Issues

Wilting, yellowing leaves, or stunted growth in excessive heat; leaf drop or browning in cold stress.

Cold Stress

Slows growth, may cause root damage, and can lead to fungal infections in cold, damp conditions.

Solution: Move to a warmer location; insulate pots; avoid overwatering in cold conditions.

Hot Stress

Leaves may scorch, wilt, or drop; growth may cease in excessive heat.

Solution: Provide shade; increase humidity; water more frequently but avoid waterlogging.

Fertilizing Guide
Fertilizing Checklist

Use diluted fertilizer; fertilize during growing season; avoid winter feeding.

Fertilizing Method

Use a balanced, diluted liquid fertilizer every 4–6 weeks during active growth (spring and summer). Avoid fertilizing in winter.

Common Problems & Solutions

Yellowing of leaves in Lobelia dortmanna may indicate nutrient deficiencies, particularly nitrogen, or water stress due to improper moisture levels in the boggy or aquatic habitat where it typically grows.

Wilting in Lobelia dortmanna is often a sign of water stress, either due to insufficient water in its aquatic or boggy environment or excessive water causing root suffocation.

Leaf spots in Lobelia dortmanna are not commonly reported, but they could be caused by fungal or bacterial pathogens if the plant is exposed to unsuitable conditions or pathogens.

Rotting, particularly root rot, can occur in Lobelia dortmanna if the soil or water conditions become too stagnant or if there is an overabundance of organic matter leading to anaerobic conditions.

Toxicity Warning

Cats
Toxic

Cats are also susceptible to the toxic effects of Lobelia dortmanna, with ingestion leading to gastrointestinal and neurological disturbances. The plant's alkaloids can cause severe symptoms, particularly in smaller animals.

⚠️ Symptoms:
vomiting diarrhea lethargy difficulty breathing tremors seizures collapse
🌿 Toxic Parts:
entire plant
⚡ Toxic If:

if eaten

Keep cats away from the plant. Seek veterinary care immediately if poisoning is suspected.
Dogs
Toxic

The alkaloids in Lobelia dortmanna can be harmful to dogs, leading to gastrointestinal upset, respiratory distress, and neurological symptoms. The plant's effects on dogs are similar to those in humans, with potential for severe toxicity if ingested.

⚠️ Symptoms:
vomiting diarrhea lethargy difficulty breathing tremors seizures collapse
🌿 Toxic Parts:
entire plant
⚡ Toxic If:

if eaten

Keep pets away from the plant. Contact a veterinarian immediately if ingestion is suspected.
Humans
Toxic

Lobelia dortmanna contains lobeline and other alkaloids that can cause significant physiological effects, including respiratory depression and central nervous system stimulation. The plant's toxicity is due to its ability to interfere with neuromuscular transmission and affect cardiovascular function.

⚠️ Symptoms:
nausea vomiting diarrhea dizziness weakness difficulty breathing convulsions hypotension
🌿 Toxic Parts:
entire plant
⚡ Toxic If:

if eaten

Keep out of reach of children and avoid ingestion. Seek immediate medical attention if poisoning is suspected.
Important: Keep this plant out of reach of children and pets. If ingestion occurs, contact poison control or veterinary services immediately.

Frequently Asked Questions

Q: Is Lobelia dortmanna suitable for beginners?

A: No, it requires specialized aquatic or semi-aquatic conditions and is best suited for expert growers.

Q: Does Lobelia dortmanna attract wildlife?

A: Yes, it is known to attract bees and other pollinators.

Q: Can Lobelia dortmanna be grown in a typical garden?

A: No, it requires acidic, nutrient-poor water conditions and is not suitable for standard garden soil.

Quick Reference
Family: Campanulaceae
Care: expert only
Light: partial shade to full shade
Water: every 7–10 days, allowing so
Suitable For: ["collectors/enthusiasts","wildlife supporters (attracts bees, butterflies, birds)"]
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