Purple Ice Plant

There are a number of different "ice plants." However, plant taxonomy places the types with which I deal here in the genus Delosperma. That genus contains a number of species; in this article I use purple ice plant (Delosperma cooperi) as an example. Delosperma cooperi (sometimes given as Mesembryanthemum cooperi) is also called "hardy ice plant."

Delosperma cooperi is a flowering, succulent perennial.

The book, Hardy Succulents, by Gwen Moore Kelaidis, was useful in my research into hardy ice plants. Purple ice plants, as their name suggests, have light purple flowers, which are daisy-like. The flowers bloom all summer.

Kelaidis remarks that Delosperma cooperi can spread to as much as 3-4 feet across. Delosperma cooperi stays relatively short (about 3 inches tall) and is procumbent in habit. The rounded, fleshy fingers of the foliage are about an inch long; the green summer color of the leaves may morph into darker colors as temperatures drop.

This succulent is indigenous to South Africa, where it is an evergreen. Belying its origin, a hardy ice plant can be grown in planting zones 5-9. At the northern end of this range, however, note 2 things:

1. Winter hardiness isn't a given. Purple ice plant may not survive a difficult winter in zone 5.
2. Its leaves won't be evergreen, even if it does survive; treat it as an herbaceous perennial.

Planting Delosperma cooperi in full sun and in a superbly well-drained soil are critical steps to growing this succulents successfully. Avoid planting in clayey soils unless you are willing to improve percolation with soil amendments. Purple ice plants are drought-resistant plants and don't require rich soils, but they hate to be sitting in water!

Despite its resistance to drought and dislike of wet feet, Delosperma cooperi will profit from an occasional watering in the heat of summer, as long as the drainage is excellent.

The drought tolerance of Delosperma cooperi makes it useful for xeriscaping. Naturals for rock gardens, these succulents can also be planted between the stones in a dry-wall stone retaining wall. Purple ice plants, which spread more vigorously than some types, make good groundcovers.

It isn't so much cold weather in zone 5 that will kill Delosperma cooperi as it is freezing temperatures combined with wet conditions. Thus a Delosperma cooperi is more likely to survive in a zone 5 region with an arid climate. Kelaidis recommends "a winter blanket of woven row cover (like Reemay)" to help over-winter it in wetter zone 5 climates.

Reduce watering in fall to help harden off Delosperma cooperi for winter. Cold will be less likely to damage their succulent leaves if they aren't quite so full of water.

As a side note, the water-retentive quality of this succulent's foliage makes it a fire retardant!

Certain types are considered invasive plants in California; e.g., Carpobrotus.

According to the New Mexico State University extension, the common name derives from the fact that "they have bladder-like hairs on the leaf surface that reflect and refract light in a manner to make it appear that they sparkle like ice crystals."

Kelaidis mentions a number of other varieties besides Delosperma cooperi; for example"

• Delosperma basuticum 'White Nugget' has white flowers
• Delosperma 'Gold Nugget' bears yellow flowers
• Delosperma 'Kelaidis' has the most unusual flower color, a salmon-pink

In addition to flower color, such features as size and growing requirements distinguish one variety from another. For example, Kelaidis calls 'White Nugget' "more of a clump-former than a ground cover" (i.e., it doesn't spread vigorously enough to be considered as effective a ground cover as Delosperma cooperi). She also indicates that Delosperma nubigenum, a variety with yellow flowers, tolerates clayey soils better than does purple ice plant.