Ornamental · Lamiaceae
Bells of Ireland
Moluccella laevis
Tall green spires of bell-shaped calyces that thrive in cool weather and dry beautifully for the vase.
Full sun
39–81°F · 4–27°C
USDA 2–11
24–35 in · 60–90 cm
Overview
Bells of Ireland earns its name from the stack of green, bell-shaped calyces marching up each tall stem, with the tiny true flowers tucked inside. Despite the name, it springs from the eastern Mediterranean to western Asia rather than Ireland. Gardeners grow it as a cool-season annual for its unusual color and striking shape, first out in the bed and then again in a vase.
This plant chases cool growing weather and balks at heat and humidity. It rockets upward, throwing spikes of 2 to 3 feet (60 to 90 cm) in a single season before bursting into bloom from mid-summer into fall. Grab gloves before you cut, though, since pairs of small, sharp spines lurk under each green bell.
Florists chase it just as keenly as gardeners do. The green calyces keep their color once cut and dry well for lasting arrangements, which is why the stems keep showing up in bouquets long after the garden winds down for the year.
Care
The short version: full sun and cool growing weather, soil kept evenly moist but never soggy, a balanced feed through the season, and a stake for the tall spikes wherever the wind whips up.
Light
Hand it full sun for the strongest, straightest spikes, though it will take a little partial shade. Pile on too much shade and you end up with weak, leaning stems and far fewer of those green bells.
Water
Keep the soil evenly moist at all times, and water through any dry spell so it never bakes. This plant hates heat, so steady summer moisture is one of the best tricks for keeping it powering along.
Soil
Drop it into loose, moderately fertile, well-drained ground that holds even moisture. It shrugs off poorer soil as long as drainage stays sharp, and a pH anywhere from 6.0 to 7.5 keeps it happy.
Temperature
This cool-weather plant performs best between roughly 39°F and 81°F (4°C to 27°C). Crank up the heat and humidity of high summer and it starts to slow down and fade.
Humidity
Plain outdoor air does the job, so skip chasing any number. Humid, muggy heat is the real enemy, so give the plants room and keep air moving around them.
Feeding
A balanced general-purpose fertilizer once a month through the growing season covers it. Hold back, though, since soft, overfed growth flops far more easily.
Pruning
Cut the flower spikes for fresh or dried use, and deadhead before the seed sets to keep the self-sowing in line. In windy spots the tall spikes usually want a stake to stand tall.
Size & spacing
Count on plants hitting 2 to 3 feet (60 to 90 cm) tall. Set them about 12 to 18 inches (30 to 46 cm) apart, close enough that neighboring stems prop each other up.
When to plant
Bells of Ireland runs on cool weather and stalls in the heat, so nailing the timing makes the whole thing sing. Start seed indoors in late winter, move plants out a few weeks before the last frost once nights hold above 40°F (4°C), and the spikes blaze from mid-summer into fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 8 to 10 weeks before the last spring frost; barely cover seed as light aids germination, which can be slow (up to a month).
- Plant: A few weeks before the last frost, or transplant once night temperatures stay above 40°F (4°C).
- Harvest: Blooms mid-summer to fall (July to September); cut stems for fresh use, or before seed ripens for drying.
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Almost every hiccup with this plant comes down to two things: summer heat and the sheer height of its spikes. Spot the early signs below and you can jump in before a small setback dents the display.
Spikes fizzling out just as summer heats up
Bells of Ireland thrives as a cool-season plant, so when heat teams up with humidity it runs out of steam and the spikes start to fade and bloom slows right down. Plant it in full sun where breezes sweep through, keep the soil evenly moist, and sow early to push the whole flower show ahead of the summer peak. Time it well and the planting hits its stride while the weather still suits it.
Fix:
- Site in full sun with good air circulation
- Keep soil evenly moist during heat
- Sow early so plants bloom before peak summer heat
Barely a seedling showing a month after the seed went in
Slow germination almost always traces back to seed buried too deep or sitting at the wrong temperature. This seed sprouts in response to light, so leave it barely covered and feed it warm days around 80°F to 86°F (27°C to 30°C) with cooler nights near 60°F (16°C). Then hold steady, because even when everything lines up the seedlings can take up to a month to break through.
Fix:
- Barely cover seed as light aids germination
- Provide warm day temperatures around 80 to 86°F and cooler nights near 60°F
- Be patient; germination can take up to a month
Wind and rain knocking the tall spikes sideways
These spikes shoot up tall and top-heavy, so one strong gust or a heavy downpour sends them tipping, with the tallest leaning first. Drive a stake in early wherever the wind reaches, and tuck the planting into a sheltered corner whenever you can. Space the plants about a foot apart so they brace each other, and ease off the rich soil that pumps out soft, weak growth.
Fix:
- Stake taller spikes
- Provide a sheltered, less windy location
- Space plants about a foot apart for mutual support
Toxicity
Great news for homes with pets and kids, because this plant is not considered poisonous to animals or people. The one real hazard is physical, not chemical: pairs of sharp little thorns hide beneath each green bell, so pull on gloves whenever you handle or cut the stems.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats can prowl right past it without trouble, since no reports tie the plant to poisoning and it carries no toxic listing. Just watch the small stem spines, which might prick a curious cat's mouth.
Dogs None
Dogs romp around it perfectly safely, because nothing in the plant counts as poisonous. Chew a stem and the worst they get is a sting from the hidden thorns, nothing serious.
Horses Safe
Horses run no toxic risk here at all. The sharp spines under each calyx tend to make it a thoroughly unappealing mouthful anyway.
Rabbits Safe
Rabbits stay safe, since nothing in it will poison them. The prickly stems usually send them off before they nibble much.
Livestock Safe
Grazers like cattle, goats, and sheep meet no toxin in this plant. Most steer clear of the spiny spikes on their own anyway.
Birds Safe
Backyard birds can flit around it safely, since no part of the plant is known to harm them.
People Safe
People face no poisoning risk from it either. Pull on gloves before cutting stems, though, because the thorns hiding under the green bells are sharp enough to draw blood.
Pairs of small thorns or spines hide below each calyx along the stems and are sharp to the touch; wear gloves when handling or harvesting.
Varieties
Only a couple of named selections run alongside the wild species, each picked for one standout trait. These are the two worth chasing down.
Pixie Bells
A compact charmer with shorter, sturdier stems that hold up far better and rarely flop the way the species does.
Long Spike
Bred for its extra-long flower spikes, it is exactly what cut-flower arrangers go hunting for.
How to propagate
Bells of Ireland grows from seed, and the seed packs a few quirks worth nailing before you sow.
SeedModerate
Sow indoors 8 to 10 weeks before last frost, or outdoors a few weeks before last frost; often self-seeds in the garden. · Germination can take up to a month; plants bloom the same season from mid-summer to fall.
Kick it off from seed indoors 8 to 10 weeks before your last frost, or sow it straight outdoors a few weeks before. Leave the seed barely covered, since light helps it sprout, and give it warm days around 80°F to 86°F (27°C to 30°C) with cooler nights near 60°F (16°C). Hold your nerve, because germination can take up to a month, but then the plants race into bloom that same season from mid-summer into fall, and they often drop seed and bounce back on their own the next year.
Myths
Bells of Ireland comes from Ireland.
The name throws everyone off. This plant is native from the eastern Mediterranean across to western Asia and India, nowhere near Ireland, and the common name almost certainly just plays on the green color of its bell-shaped calyces.
The seed stays dormant until it gets a proper cold snap.
Plenty of guides tell you to chill the seed first, but the research simply does not back it. Surface sowing with light and the right temperatures is what really drives germination, not a stint in the cold.