How to Grow Lisianthus
Eustoma grandiflorum
Lisianthus are premium cut flowers with rose-like blooms and outstanding vase life. They need an early start — sow seeds on the surface in January or February at 20-25C with good light. Germination takes 2-4 weeks and seedlings grow slowly. Transplant into fertile, well-drained soil in full sun after the last frost. Pinch tips to encourage branching. Feed fortnightly and keep well watered but not waterlogged. Patience is rewarded with elegant blooms from midsummer.
When to Start
Sow indoors 13 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 15°C.
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Growth Stages
Approximate days from start
Care Essentials
- Balanced liquid feed fortnightly once transplanted. Switch to high-potash feed when buds form.
- Lisianthus are notoriously slow to start — seeds are tiny and need light, warmth, and patience. Sow early (January to February) for summer flowers. Once established they are rewarding cut flowers with exceptional vase life.
Growing Conditions
- Min. soil temperature
- 15°C+
- Germination temperature
- 20–25°C
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
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Spacing & Planting
| Plant spacing | 20 cm |
| Row spacing | 30 cm |
| Sow depth | 0 cm |
| Mature height | 60 cm |
| Mature spread | 25 cm |
Space plants 15-20cm apart in rows 30cm apart. Lisianthus are slow-growing and compact, so close spacing helps stems stay upright and reduces the need for netting.
Pests & Diseases
Pest Aphids
Identification: Clusters of small green insects on shoot tips and flower buds, causing distorted growth and sticky honeydew.
- Squash by hand or blast off with a gentle water spray
- Spray with fatty acid-based insecticide
- Introduce biological controls such as Aphidius wasps under cover
- Spray with a contact insecticide containing deltamethrin
Pest Fungus Gnats
Identification: Tiny dark flies hovering around compost surface. Larvae are translucent white grubs in the top layer of compost that damage fine roots.
- Allow compost surface to dry between waterings
- Apply Steinernema feltiae nematodes as a biological drench
- Use yellow sticky traps to catch adults
- No effective chemical controls for home growers
Disease Grey Mould (Botrytis) Botrytis cinerea
Symptoms: Fuzzy grey mould on petals, stems, and leaves, especially in humid conditions. Buds may rot before opening.
Treatment: Remove and destroy affected parts promptly. Improve ventilation and reduce humidity.
Prevention: Space plants well for airflow. Avoid overhead watering. Remove spent flowers promptly.
Disease Fusarium Wilt Fusarium oxysporum
Symptoms: Yellowing and wilting of leaves on one side of the plant, progressing upwards. Stems may show brown discolouration when cut.
Treatment: Remove and destroy affected plants. Do not replant lisianthus in the same soil.
Prevention: Use fresh, sterile compost. Avoid overwatering. Rotate planting positions each year.
Disease Damping Off
Symptoms: Seedlings collapse at soil level, stems become thin and water-soaked. Patches of seedlings die suddenly.
Treatment: Remove affected seedlings and surrounding compost. Improve ventilation.
Prevention: Use clean pots and fresh compost. Water from below. Avoid overcrowding and overwatering. Maintain good air circulation.
Growing Conditions
| Min. soil temperature | 15°C |
| Germination temperature | 20–25°C |
| Base growth temperature | 10°C |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Lisianthus?
- Plant Lisianthus 20cm apart with 30cm between rows.
- When does Lisianthus flower?
- Lisianthus typically flowers approximately 90 days after transplanting.
- Is Lisianthus frost hardy?
- Lisianthus is classified as Half Hardy.
