Members of the Mesembryanthemum Plant Genus are half hardy annuals and perennial succulents. They are often known as Ice Plants and they are useful in the garden as coverage, they are also well known for having very long lasting flowers.
Mesembryanthemum eurystigmatum photograph by Dr. Alexey Yakovlev; Creative Commons.
These flowers are daisy like and usually have rays of pink, white, red, or yellow, and a central disc of yellow. They bloom from spring to the end of summer (dependent upon species).
Plants reach heights from 10 to 30 cm (4 to 12 inches), making them ideal for use in rock gardens or at the front of borders.
As a succulent they are able to grow in harsh conditions, such as saline soils found at salt marshes and in Coastal regions that have sand dunes and flats.
Some common names for Mesembryanthemum plants include Fig Marigold, Sea fig, Ice plant, heartleaf ice plant, baby sun rose and Hottentot fig.
Crystalline Ice Plant photograph by Judy Gallagher; CC.
As a halophyte (salt loving plant) it has become the focus of scientific research for land areas that need to have salt removed to lower the concentrations.
The plant gets its common name “Ice Plant” is because the stems, leaves, and even fruit are covered in globular cells. These glisten in sunlight and are said to resemble ice crystals.
It is difficult to estimate how many species this plant genus contains as there are many synonyms, with the plant list suggesting that there may be as few as five true species in this genus. Numerous members of this genus have now been transferred to different plant genera following genetic sequencing.
Commonly listed species in the genus include the following:
Mesembryanthemum cordifolium - the Heartleaf iceplant. NB. Reclassified as Aptenia cordifolia This succulent is named after its heart-shaped (cordate) leaves. It is a carpet growing plant and so can prove useful for ground coverage in smaller gardens. It only opens its flowers when the sun is shining. It is often grown as an hybrid form in the garden known as Aptenia 'Red Apple'. This hybrid has bright green flowers and blooms with red flowers.
Mesembryanthemum crystallinum - Ice Plant. This is a short-lived prostrate growing succulent. It has large bladder cells that retain water. mesembryanthemum crystallinum plants grows well on sandy soils that have good drainage. Crushed leaves can be used as a replacement for soap.
Mesembryanthemum nodiflorum - Slenderleaf iceplant. Succulent annual plant that is invasive in many areas including the Western USA and Australia; it thrives and can grow out of control in moist soils. It grows in clumps and is mat-forming. Leaves are slender, knobbly, and green to bright red. The stems are relatively long at 20 cm (8 inches) and carry solitary flowers.
Ice Plant and Fig Marigold (Mesembryanthemum) seeds should be sown outdoors sequentially from just after the last frost of spring until the end of May; this will result in a long blooming period.
It is best to sow the seeds on the surface into a sunny part of the garden that has good drainage.
Plants prefer a soil that is sandy and dry, ideally the soil should also be poor in nature.
If growing Mesembryanthemum indoors first, then start the process about three months in advance.
The seeds will take about three weeks to germinate in the dark, at a temperature of about 18 to 24° C (64 to 75°F).
Once growing strong, smaller species can be put out into the garden following the last frost of spring, space at about 15 cm (6 inches) apart, while larger varieties should be spaced at about 20 to 30 cm (8 to 12 inches).
Once growing, it is best to water Mesembryanthemum regularly, and apply a liquid fertiliser once the first round of flowering has occurred.
Common Names: Ice plant, Fig Marigold, Icicle Plant, Pebble Plant, Heartleaf ice plant, Sea Marigold, Dumpling, Sea Fig, Baby sun rose, or Australian midday flower.
Life Cycle: Half hardy annual. Half hardy perennial.
Height: 4 to 8 inches (10 to 20 cm). Stems are prostrate and can reach about 2 feet (60 cm).
Native: Southern Africa.
Garden Usage Bedding plant, Ground cover, Rock gardens.
Growing Region: Frost tender. Zones 3 to 10 as an annual. Perennial in zones 8 to 11. UK zone: H3.
Blooms: Spring, summer, and autumn.
Flower Details: Pink, white, yellow, red. Open up on sunny days only. Daisy-like ray and disc florets. Solitary or loose flower clusters. Massed blooms. Long lasting flowers.
Foliage: Green through red. Succulent. Fleshy leaves.
Sow Outside: Surface. Sow out at two to three week intervals from just after the last frost until the middle of spring. Spacing 6 to 10 inches (15 to 25 cm).
Sow Inside: Germination time: two to three weeks. Temperature 70°F (21°C). Two months before expected last frost. Transplant outdoors following the last frost.
Propagate: Cuttings in spring.
Requirements: Full sunlight. Good drainage. Sandy soil. Grit. Poor soils. Can survive in dry soils once established. Occasional watering during prolonged dry spells. Supply a feed to perennials after flowering has finished.
Miscellaneous Medicinal use. Leaves possibly used as a traditional substitute for soap.
References / Further Reading: Awkward Botany; The Plant List.