Ornamental · Lamiaceae
Bells of Ireland
Moluccella laevis
Tall green spires of bell-shaped calyces that love 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 takes its name from the ring of green, bell-shaped calyces stacked up each tall stem, with the tiny true flowers resting quietly inside. The name can fool you, since it actually comes from the eastern Mediterranean to western Asia and not from Ireland at all. Most gardeners grow it as a cool-season annual for its unusual color and graceful shape, both in the bed and later in a vase, and it is a forgiving plant to learn on.
What this plant asks for is cool growing weather, and it would rather skip the heat and humidity of high summer. It grows up quickly and willingly, sending up spikes of 2 to 3 feet (60 to 90 cm) in a single season before blooming from mid-summer into fall. Just remember that pairs of small, sharp spines hide under each green bell, so slip on gloves before you cut a stem and you will be glad you did.
Florists are every bit as fond of it as gardeners are. The green calyces keep their color once cut, and they dry well for lasting arrangements, which is why the stems keep showing up in bouquets long after the garden itself has settled down for the year.
Care
The short version: give it full sun and cool growing weather, soil kept gently moist but never waterlogged, a balanced feed through the season, and a friendly stake for the tall spikes wherever the wind picks up.
Light
Treat it to full sun for the strongest, straightest spikes, though a little partial shade is perfectly fine too. Too much shade tends to give you weaker, leaning stems and fewer of those lovely green bells, so brighter is better.
Water
Aim to keep the soil evenly moist at all times, and offer a drink through any dry spell so the roots never bake. Since this plant dislikes heat, steady summer moisture is one of the kindest ways to keep it happy and going.
Soil
Settle it into loose, moderately fertile, well-drained ground that stays evenly moist. It will put up with poorer soil as long as drainage stays sharp, and a pH anywhere from 6.0 to 7.5 suits it just fine.
Temperature
This is a cool-weather plant that does best between roughly 39°F and 81°F (4°C to 27°C). When the heat and humidity of high summer arrive, it begins to slow and fade, and that is simply its nature.
Humidity
Ordinary outdoor air is all it needs, so there is no number to chase. Humid, muggy heat is the real challenge, so give the plants a little room and keep the air moving gently around them.
Feeding
A balanced general-purpose fertilizer once a month through the growing season is plenty for this plant. Resist the urge to feed heavily, since soft, overfed growth tends to flop more easily.
Pruning
Cut the flower spikes freely for fresh or dried use, and deadhead before the seed sets if you would like to keep the self-sowing in check. In breezy spots the tall spikes often appreciate a stake to stay upright.
Size & spacing
You can expect plants to reach 2 to 3 feet (60 to 90 cm) tall. Set them about 12 to 18 inches (30 to 46 cm) apart, which is close enough that neighboring stems gently help hold one another up.
When to plant
Bells of Ireland is happiest in cool weather and tires in the heat, so good timing makes all the difference and is easy to get right. 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 will bloom 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 friendly culprits: summer heat and the sheer height of its spikes. Catch the early signs below and you can step in gently, well before any small setback dims the display.
Growth slows and blooms fade when hot weather arrives
Take heart, because this is normal behavior rather than a mistake you made. Bells of Ireland is a cool-season plant at heart, and a stretch of hot, muggy weather is simply more than it enjoys, so the spikes soften and the blooms slow as summer peaks. Give it full sun where the air can move freely, keep the soil gently moist, and sow on the early side, and you will see most of the show finish before the heat arrives.
Fix:
- Site in full sun with good air circulation
- Keep soil evenly moist during heat
- Sow early so plants bloom before peak summer heat
Hardly any seedlings showing, even a month past sowing
If the seed tray still looks bare, you have likely done nothing wrong, since slow germination usually points to seed buried a touch too deep or sitting at the wrong temperature. The seed wants light to wake up, so rest it right at the surface and offer warm days around 80°F to 86°F (27°C to 30°C) with cooler nights near 60°F (16°C). Then give it time, because even when everything is right the seedlings can take up to a month to appear.
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
Stems bending over after a gusty or rainy spell
Don't be discouraged if your tallest spikes tip over, because their top-heavy shape simply catches the wind and a heavy rain can press them down. A little support set in place early solves it, so add a stake in any breezy corner and choose a spot that is tucked out of the wind. Planting them about a foot apart lets neighboring stems lean on each other, and an easy hand with rich feed keeps the growth firm instead of soft.
Fix:
- Stake taller spikes
- Provide a sheltered, less windy location
- Space plants about a foot apart for mutual support
Toxicity
Here is the reassuring part for homes with pets and little ones, because this plant is not considered poisonous to animals or people. The only real hazard is a physical one rather than a chemical one: pairs of sharp little thorns hide beneath each green bell, so reach for gloves whenever you handle or cut the stems.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
You can relax about cats, since nothing here is known to poison them and the plant carries no toxic listing. The only thing worth a gentle watch is the small spines on the stems, which could give a curious cat a little prick on the mouth.
Dogs None
Dogs are welcome to share the garden, because nothing in the plant counts as poisonous. Should one nibble a stem, the worst it might feel is the sting of a hidden thorn rather than any true harm.
Horses Safe
There is no toxic worry for horses with this plant. The sharp spines beneath each calyx tend to make it an uninviting bite all on their own.
Rabbits Safe
Rabbits stay safe, as the plant holds no poison for them. The prickly stems usually discourage them long before they manage much of a meal.
Livestock Safe
Grazing animals like cattle, goats, and sheep have nothing toxic to fear here. Most simply leave the spiny spikes be without any prompting.
Birds Safe
Garden birds can happily share the space, since no part of the plant is known to do them harm.
People Safe
There is no poisoning risk for people to worry about. A simple pair of gloves at cutting time is all you need, because the thorns tucked under the green bells are sharp enough to nick a finger.
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
Just a couple of named selections turn up alongside the wild species, and each one was chosen for a single helpful trait. These are the two worth getting to know.
Pixie Bells
A neat, compact pick whose shorter, sturdier stems stand up far more reliably and rarely tip over the way the plain species tends to.
Long Spike
Prized for its extra-long flower spikes, it is the kind that cut-flower arrangers happily reach for.
How to propagate
Bells of Ireland is grown from seed, and the seed itself has a few small quirks that are easy to get right once you know them.
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.
Growing this one from seed is well within reach, so start it indoors 8 to 10 weeks before your last frost, or settle it straight into the ground a few weeks beforehand. Rest the seed near the surface since light helps it sprout, and keep warm days around 80°F to 86°F (27°C to 30°C) with cooler nights near 60°F (16°C). Patience is the main thing, because germination can take up to a month, yet the plants reward you with blooms that same season from mid-summer into fall, and they often drop their own seed and return the following year.
Myths
Bells of Ireland comes from Ireland.
The name leads you astray here. This plant is native from the eastern Mediterranean across to western Asia and India, far from Ireland, and the common name most likely just celebrates the green color of its bell-shaped calyces.
You must chill the seed in the cold before it can sprout.
You may have read that the seed needs chilling first, yet the research simply doesn't support it. The things that truly count are surface sowing with light and the right temperatures, not a stint in the cold.