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How to Grow Marjoram

Origanum majorana

Tender Warm Season Continuous Harvest

When to Start

Start seeds indoors 4 weeks before your last frost date. Transplant outdoors once night temperatures stay above 8°C and soil has warmed to at least 10°C.

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Growth Stages

Germination ~12d
Harvest ~75d

Approximate days from start

Care Essentials

  • Rarely needed. Prefers poor to moderate, well-drained soil.
  • Sweet marjoram has the best flavour but is frost-tender. Pot marjoram (oregano) is hardier but coarser.

Companion Planting

Growing Conditions

Min. soil temperature: 10°C+
Germination temperature: 18–22°C

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Spacing & Planting

Plant spacing 25 cm
Row spacing 30 cm
Sow depth 0 cm
Mature height 30 cm
Mature spread 30 cm

Sweet marjoram is frost-tender in the UK; grow as a summer annual.

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Care Guide

Feeding
Rarely needed. Prefers poor to moderate, well-drained soil.
Watch for
  • Aphids
  • Spider mites

Pests & Diseases

Pest Aphids

Identification: Clusters of small green insects on growing tips, sticky honeydew, distorted new growth

Organic treatment:
  • Blast off with a jet of water
  • Encourage ladybirds and hoverflies
  • Soft soap spray
Chemical treatment:
  • Pyrethrum-based contact insecticide
Pest Red Spider Mite

Identification: Fine webbing on shoot tips, tiny red-brown mites on leaf undersides, leaves become speckled and bronzed

Organic treatment:
  • Increase humidity by misting regularly
  • Biological control with Phytoseiulus persimilis predatory mites under glass
  • Remove badly affected shoots
Chemical treatment:
  • Fatty acid or plant oil-based sprays
Disease Root Rot Phytophthora spp. / Pythium spp.

Symptoms: Wilting despite moist soil, yellowing leaves, soft brown roots, plant collapses

Treatment: Remove affected plants. Improve drainage before replanting.

Prevention: Plant in well-drained soil or add grit to heavy ground. Use terracotta pots with good drainage. Water sparingly.

Disease Powdery Mildew Erysiphe spp.

Symptoms: White powdery coating on leaves and stems, affected leaves yellow and drop

Treatment: Remove affected growth. Improve air circulation.

Prevention: Space plants well. Avoid overhead watering. Grow in full sun with good airflow.

Growing Conditions

Min. soil temperature10°C
Germination temperature18–22°C
Base growth temperature8°C
Min. daylength to start10.5h
Photoperiod sensitivityday neutral

Frequently Asked Questions

How far apart should I plant Marjoram?
Plant Marjoram 25cm apart with 30cm between rows.
When can I harvest Marjoram?
Marjoram is ready to harvest approximately 45 days after transplanting.
Is Marjoram frost hardy?
Marjoram is classified as Tender.

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