Even if you only have room for a few Gasterias in your collection, Gasteria armstrongii is one you must surely grow. It was first described by Schönland in 1912, reassigned as a variety of G. nitida by van Jaarsveld in 1992, and then reverted to species level on the basis of DNA studies (Zonneveld and van Jaarsveld) in 2005.
As with many Gasterias, the juvenile form of the plant can look quite different to the mature adult. A young G. armstrongii is distichous (= alternate leaves grow at 180 degrees to each other) and the leaves are often quite rough, whilst an adult plant remains distichous but the leaves become glossy and smooth. Contrast this with G. nitida where the adult plant forms a rosette.
Gasteria armstrongii is easy to grow; use a well draining compost (e.g. John Innes: coarse grit, 1:1) to avoid loss of the quite tuberous roots, and water from March to September (northern hemisphere) keeping dry and frost-free at all other times. Be careful with the first watering of the season that you don’t give it too much water as the leaves sometimes have a propensity to split, and partial shading is advised to avoid any scorching. Mature plants have a typical Gasteria inflorescence of many stomach-shaped orange/green flowers on a single stem in summer.
Plants in habitat (occurring only between Humansdorp and the Gamtoos River in the Eastern Cape of South Africa) grow level with the ground making them very difficult to spot. In contrast, those grown in pots develop into plants with chunky, succulent leaves sitting well proud of the soil level.
Whilst you see old clumps of large-headed plants of this species from time to time, particularly say at National and Zone Shows, mature single-headed plants are equally rewarding. A given plant may only grow one new leaf each year, hence it won’t outgrow the space available on your bench very quickly (so even a cactophile or Haworthia lover should find room for one of these!).
Tony Roberts
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