How to Grow Bells of Ireland
(Moluccella laevis) from Seed
The florist's essential green — architectural spikes of apple-green bells running up 60–75cm stems, carrying tiny fragrant white flowers within each bell, and equally spectacular fresh or dried in arrangements
In the professional floristry trade, Bells of Ireland holds a position of particular importance — it is considered a primary green, the plant that provides vertical architectural structure and fresh apple-green colour in arrangements in a way that no other annual quite replicates. The stems carry large, cup-shaped calyxes — the technical term for the "bells" — running from top to bottom in a spiral that gives the spike a rhythmic, architectural quality. Nestled inside each bell is a tiny white flower of intense fragrance that the casual observer often misses entirely, but which fills any room where cut stems are placed with a sweet, spicy scent.
Despite the name, Bells of Ireland is not Irish — Moluccella laevis is native to the Mediterranean and Middle East, where it grows in open, sunny, well-drained habitats from Syria to Turkey. The name may derive from an early association between green flowers and Ireland, or possibly from a misidentification with the Molucca Islands, though neither theory is well-supported. Whatever the etymology, the common name has stuck and the plant has become one of the most recognised and most used green cut flowers in the world, holding the RHS Award of Garden Merit as recognition of its exceptional garden and cutting value.
Quick Facts at a Glance
Plant Type
Hardy to Half-Hardy Annual
Sowing Time
Feb–Apr (stratify first · individual modules)
Flowering Months
July – September
Position
Full sun; well-drained
Height & Spread
60–75cm · 25cm
Difficulty Rating
3 out of 5 — Moderate
Understanding the Plant
Moluccella laevis belongs to the Lamiaceae family — the same mint family as lavender, salvia and basil — which explains the square stems and aromatic quality of the small white flowers within each bell. The "bells" themselves are not the flowers but the calyxes — the protective structures that surround the base of each flower and in this plant are dramatically enlarged into the cup-shaped structures that give the plant its common name. As the flowers fade and fall, the calyxes remain and gradually harden and bleach to a pale parchment colour — which is why dried stems of Bells of Ireland are so long-lasting.
The plant produces a taproot that is easily damaged at transplanting, which is the most important practical characteristic to understand. Bells of Ireland transplants very poorly when the taproot is disturbed — plants that have been grown in standard seed trays and then tipped out and separated often stunt or die. Sowing into individual deep modules, or biodegradable pots that can be planted out intact, is the correct approach.
The Bells Are Calyxes, Not Petals
Understanding the botany of Bells of Ireland helps explain why they look and behave differently from most cut flowers. The large, cup-shaped structures that run up the stem are not petals — they are calyxes, which are normally the small green sepals at the base of a flower. In Moluccella, these calyxes are dramatically enlarged and form the ornamental part of the plant. The actual flowers are the tiny, intensely fragrant white blooms inside each bell. This is why Bells of Ireland maintain their form as they age (the structural calyxes are robust) and why they dry so well (the hard calyx persists long after the flower falls).
⚠️ Hidden Thorns — Wear Gloves When Stripping
Bells of Ireland stems carry small, sharp thorns hidden beneath the foliage along the length of the stem. These are not obvious until handling, and they can cause painful scratches when stripping the lower leaves before arranging. Always wear gloves when handling and preparing stems for the vase. Once stripped, the clean, architectural stems are entirely safe to handle without protection.
When & How to Sow
Bells of Ireland seed has a hard coating and requires cold stratification to break dormancy reliably. Without it, germination is slow, erratic and often poor. With it, germination is significantly improved. The seed is also photoblastic — it needs light to germinate, so surface sowing is essential. The taproot sensitivity means individual modules or biodegradable pots are non-negotiable.
The 14-Day Cold Trick
Before sowing, place the sealed seed packet in the salad drawer of the fridge for 14 days. This cold stratification mimics the Mediterranean winter the seed would experience naturally and breaks the dormancy of the hard seed coat, producing significantly faster and more uniform germination. Surface sow immediately after removing from cold storage — don't allow the seed to warm for days before sowing.
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Cold-stratify the seed for 14 days in the fridge. Place the sealed packet in the salad drawer. After 14 days, remove and sow within a few days. Some growers additionally soak the stratified seed in water for 12–24 hours to further soften the seed coat before sowing — this can improve germination further.
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Sow into individual deep modules or biodegradable pots. This is the most important practical step. Bells of Ireland has a taproot that cannot be disturbed at transplanting without causing permanent damage. Surface sow — press the seed gently onto moist compost without covering. Light is needed for germination.
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Maintain 15–18°C until germination. Cooler than most annuals — Bells of Ireland germinates better at moderate temperatures than at the higher end used for half-hardy annuals. Germination takes 21–28 days. Be patient and do not disturb the modules.
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Grow on in cool, bright conditions. Once germinated, Bells of Ireland grows steadily. Do not pot on — grow in the module until planting out, to avoid any taproot disturbance. Plants grown in biodegradable pots can be planted pot and all, eliminating all root disturbance.
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Harden off and plant out from late April. Bells of Ireland is reasonably cold-tolerant and can go out before the last frost date. Space 25–30cm apart in full sun and well-drained soil. Handle the root ball with the greatest possible care — any taproot damage at transplanting stunts or kills the plant.
Growing On Tips
Full Sun
Full sun produces the strongest, most upright stems and the most vivid apple-green colour. In partial shade, stems become drawn and the colour paler. Bells of Ireland is native to open, sunny Mediterranean habitats and performs best in conditions that reflect this origin.
Drainage
Well-drained to freely draining soil is preferred — Bells of Ireland tolerates drought far better than waterlogging. In heavy clay, improve drainage before planting with grit or raised beds. Waterlogged conditions cause root problems and poor stem quality even in plants that survive.
Staking Tall Stems
At 60–75cm, Bells of Ireland can become top-heavy and may need support in exposed or windy positions. Place bamboo canes or twiggy pea-sticks before stems reach 30cm. In sheltered, sunny positions with well-drained soil, stems are often adequately self-supporting.
Cutting Fresh
Cut when the bells on the lower half of the stem are fully formed and the tiny white flowers inside are visible — this is when fragrance is strongest and vase life is longest. Cut with long stems. Strip the lower leaves wearing gloves (hidden thorns). Remove any leaves below the water line. Condition in deep cool water before arranging. Vase life is 10–14 days.
Drying for Arrangements
Bells of Ireland dried stems are outstanding and can last for years. Cut when the bells are fully formed but the tiny flowers are still present — before the flowers fall and the bells begin to bleach. Hang upside down in small bunches in a dark, dry, well-ventilated space for two to three weeks. The dried stems are pale parchment in colour and retain their architectural form perfectly.
Self-Seeding
Bells of Ireland self-seeds reliably in warm, sheltered conditions with bare or disturbed soil nearby. Allow some stems to set seed in late summer — the seedlings that appear in autumn or early spring have the advantage of natural cold stratification and often germinate far more reliably than indoor-sown seed. In mild gardens, a self-seeding colony can establish itself with minimal ongoing effort.
Common Problems & How to Fix Them
| Problem | Likely Cause | What to Do |
|---|---|---|
| No or very poor germination | Seed not stratified; seed covered; old seed | Stratify for 14 days in the fridge before sowing. Surface sow without covering — Moluccella is photoblastic and covered seed rarely germinates. Use fresh seed; germination rates decline markedly in seed more than one year old. Alternatively, sow in autumn and allow natural winter stratification outdoors. |
| Plants stunt or die after transplanting | Taproot damaged at transplanting | This is the most common cause of failure with Bells of Ireland. Always sow into individual deep modules or biodegradable pots. Never prick out from seed trays. At planting out, disturb the root ball as little as possible. Plants with damaged taproots rarely recover; prevention is the only solution. |
| Stems collapsing in wind | Tall plants without support in exposed position | Install support before stems reach 30cm. Use bamboo canes and soft ties, or twiggy pea-sticks placed early enough for stems to grow naturally through and around them. In sheltered positions, well-grown plants on free-draining soil are usually self-supporting. |
| Pale, washed-out green colour | Insufficient sun, overwatering, or overfeeding | Ensure full sun. Avoid overwatering — free drainage produces the deepest green. Minimal feeding is needed; Bells of Ireland does not need rich soil and an overfed plant produces pale, lush growth with poor stem quality. Lean conditions produce the best colour. |
| Scratches when handling | Hidden thorns on stems | Always wear gloves when stripping lower leaves from cut stems. The thorns are present on all plants and are not obvious until handling. Once the leaves are stripped and stems are clean, they can be handled safely without gloves. |
When to Expect Flowers
The term "flowers" is slightly misleading for Bells of Ireland — the tiny white flowers inside the bells are not the ornamental feature, and the stems are cut for the bells themselves, which develop through summer and are at their most useful from July onwards. From a February or March sowing with proper stratification, stems reach cutting quality from July. The display continues until September, or until the first heavy frosts. Seeds sown directly in autumn — left outside over winter for natural stratification — often produce earlier, stronger stems from May or June the following year.
Stratify for 14 days, sow into individual modules — architectural green bell-spikes appear from July, lasting 10–14 days fresh or indefinitely when dried. Direct autumn sowing produces earlier, stronger stems.
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| 🌱 Sow Indoors |
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| 🪴 Plant Out |
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| 🔔 Bells Ready |
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Plant Specifications
The florist's green that transforms any arrangement it enters
Bells of Ireland is the plant that professional florists reach for when they want vertical architectural structure and that clean, vivid apple-green that makes every other flower in the vase look more saturated and more alive. The cold stratification, the individual modules, the taproot care — these are the small investments of attention that unlock a genuinely exceptional cutting garden plant. Stratify for 14 days, sow into deep modules, plant out carefully, strip with gloves — and then stand back and discover why this RHS Award of Garden Merit holder has been a professional floristry staple for generations.
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