How to Grow and Care for Bells of Ireland

Before green flowers became a hot trend among plant breeders, there were bells of Ireland (Moluccella laevis), an annual flowering plant in cultivation since the 1500s. These plants produce tiny, fragrant white flowers surrounded by apple-green calyxes clustered along vertical square green stalks. The green bell is the calyx—outer sepals surrounding the tiny white flower petals inside.

Florists love bells of Ireland for their availability and longevity, and you’ll see them used in wedding flower arrangements as often as in St. Patrick’s day bouquets. As a member of the Lamiaceae family, this plant is related to such ornamental and culinary plants as sage (Salvia), catmint (Nepeta), thyme (Thymus), and lavender (Lavandula).

Bells of Ireland is generally planted in the spring, from seeds either sown directly into the garden or from seeds started indoors at least two months before the last expected frost of spring. It can take 12 to 21 days for seeds to germinate and sprout and another two months before they mature into flowering plants.

Bells of Ireland Care

Native to regions of western Asia, such as Turkey, Syria, and the Caucasus, bells of Ireland is an annual that grows in all zones but fares poorly in areas with hot and humid summers. Shade cloth can go a long way towards prolonging the vigor of the plants when summer heat kicks in.

If you are lucky enough to find a well-stocked nursery with plugs or young plants, it's worth the extra money to start with these the first season. Doing this allows you to see if bells of Ireland grow well in your area without a significant investment of time or effort. If they take off, you can plant a more extensive patch the following season using seeds saved from plants. 

Bells of Ireland are top-heavy, and they may topple over after heavy rain or in areas exposed to wind. Plants growing in partial shade may also need staking, as they can become leggy. Stake the blooming stalks, grow the compact variety, or grow them in a sheltered area to keep the spires upright.

Bells of Ireland don't re-bloom, so that you can remove plants past their prime without guilt. However, you may want to leave them in place long enough for the seeds to mature and scatter, as these annuals are self-sowing. The flower stalks also look lovely in dried arrangements.

Light

Full sun is best for bells of Ireland. The plants need at least some morning sun to prevent them from growing too leggy, which makes them prone to flopping. Plants in shady locations will almost certainly need staking.

Soil

These plants like soil with a neutral pH (6.5–7.5) that drains well and is kept evenly moist. It's best to blend some compost into the planting area before sowing seeds.

Water

Keep bells of Ireland consistently moist during the vulnerable seedling and transplant stages. Soaker hoses are great for providing moisture without water-logging the plants. These plants will do well with about 1 inch of water per week. Mulch helps preserve moisture in the soil.

Fertilizer

Bells of Ireland plants require little, if any, feeding. Preparing the planting bed for them with compost should be enough. However, in very poor soil, you may need to fertilize. Follow the directions on the label.

Types of Bells of Ireland

A few cultivars of Moluccella laevis are available; one very popular variety is 'Pixie Bells'. It has shorter, sturdier stems that are much less likely to topple over when the plants get wet. Most gardeners prefer it over the origin species plant.

Propagating Bells of Ireland

The easiest way to propagate this plant is to collect seeds from the drying flower heads, saving them to plant the following spring (though they will need cold stratification for best results). You can also carefully transplant some of the self-seeded volunteers that sprout up in the garden. They will be plentiful if you leave flowers on the plant to mature and dry.

How to Grow Bells of Ireland From Seed

Plant bells of Ireland in the garden after the last frost date in your area in average garden soil. Leave seeds uncovered, as they require light to germinate. The seeds are slow to germinate, taking 12 to 21 days to sprout, so for earlier blooms, start them indoors two months before the average last frost date. In mild climates, you can also sow seeds in the garden in the fall.

Stratification increases the germination rate of bells of Ireland seeds. You can expose them to cold by sowing them outdoors in the fall or refrigerating them for a week before starting them indoors. Don't just place the seed packet in the refrigerator; combine moist conditions with cold temperatures to mimic an outdoor experience for the best results. Sandwich the seeds between moist coffee filters or paper towels in the refrigerator, then plant them in the soil. Moist stratification results in a higher germination rate than simply exposing dry seeds to cold temperatures. 

Biodegradable pots are a good option for starting bells of Ireland seeds. When starting seeds indoors, it's best to plant seeds in 3-inch pots filled with seed starter mix or ordinary potting soil and wait until the plant is of good size before planting it outdoors. These plants have a taproot that doesn't like to be disturbed, so try to avoid transplanting twice—from seed trays into pots, then from pots into the ground. While waiting for the seeds to germinate and sprout, keep the potting mix moist by misting it with a spray bottle.

Harvesting

Bells of Ireland flowers are easy to dry and add interest to fresh-cut flower arrangements. The lime green calyxes make an attractive foil for wine or magenta-colored flowers, like Red Velvet celosia (Celosia argentea 'Red Velvet'), globe amaranth (Gomphrena globosa), or Purple Prince zinnia (Zinnia 'Purple Prince'). 

Cut the flowers when the bells are about half open for fresh flower arrangements. For dried flower arrangements, wait until the fully open bells have become firm to the touch.

The stiff calyxes of bells of Ireland last up to two weeks in fresh arrangements, but the flowers don’t maintain their green tint as dried specimens. The bells will gradually turn tan as they dry. For a fun bouquet twist, spray paint dried stems gold or silver and pair them with fresh green stems. 

Potting and Repotting Bells of Ireland

Like most annuals, bells of Ireland make excellent container plants. As a tall, upright spire, it's best planted in the center of a large container (any material will do) surrounded by colorful mounding and trailing annuals (purple and crimson flowering plants provide a lovely contrast) that will provide support for the spiky bells. Use a potting mix with fertilizer included to give the plants a good start. Water the container regularly. Check the soil using your finger. If the top inch is dry, it's time to water.

Bells of Ireland don't like to be transplanted, so repotting this annual isn't advised. It's also not a good candidate for a houseplant.

Common Pests & Diseases

Bells of Ireland can be subject to cerospora leaf blight, a disease that causes small flecks with yellowish halos to appear on the leaves. Crown rot can also cause the plants to wilt from the soil line up, eventually dying. Diseased plants should be removed and discarded.

Few serious garden pests threaten bells of Ireland plants, though aphids and spider mites are occasional problems.