The Pampas Grass – When And How To Use It In The Garden

There are a limited number of ornamental plants which are so spectacular in their appearance, that they can really transform a garden from being ordinary to being special. One of these is the Pampas grass, Cortaderia sellowiana, from Argentina. Unfortunately it can also be highly problematical to maintain, and even dangerous to those who use the garden. This is a pity, because as a massive ornamental grass, it is possibly unmatched in its capacity to provide drama and a sense of movement in the garden.

The danger comes from the leaves of the Pampas grass. They are serrated along the edge, making them as sharp as a carpenter’s saw. In fact the plant’s botanical name, Cortaderia, originates from the Spanish word cortar, “to cut”. For this reason Pampas grass should never be planted where children are likely to run about and play, nor close to paths and entrance ways. Bearing in mind that it can cover some 2 meters in width, it can only be considered as an option in the garden, when granted plenty of space.

Another serious problem associated with Cortaderia is its potential to spread as an uncontrollable weed, so much so that some plant nurseries in the US have stopped propagating the species altogether. The danger only arises though when male and female plants are to be found in each others proximity. In Israel, where I come from, we don’t have this problem, as the plants are propagated vegetatively, from female specimens only.

Design considerations

The Pampas grass, together with its massive plumes, can reach a height of 3-5 meters, spreading outwards from its base to form a large clump some 1-2 meters wide. The blooms, particularly the female ones, are particularly beautiful. Clearly, the role of the plant is that of a focal point. In this regard, general design knowledge and good taste come into play. As the dominant element in a composition, it should not have to compete for attention with other eye catching elements like flower beds, sculptural plants, or species with unusually colored foliage.

As a grass, it obviously associates well with other ornamental grass-like plants. Indeed a whole composition could be built around the Pampas as the centerpiece, supported by grasses that reach about a meter in height like varieties of Miscanthus and Pennisetum setaceum, while a carpet is made of low growing plants of similar form and habit, such as Carex, Festuca, Liriope, and Ophiopogon japonicum.

Cortaderia is highly suited to gardening in a dry climate where water is at a premium. It can get by pretty well with modest additions during the dry months, requiring perhaps some 300mm over the year. Planted in a large bed of ornamental pebbles, it can create a stunning focal point, while the total water consumption of the bed as a whole, could actually be less than 200mm per year. (200 liters per meter square)

Care and maintenance

The tendency of the Pampas grass to dry out at its base, coupled with the difficulties gardeners have in cutting out dead parts of the plant, is another factor behind the reluctance to use the plant. However, this is another stumbling block that can be dealt with relative ease. The clump should simply be cut down to the ground every 2-3 years, by way of a hedge trimmer, or mechanical strimmer. (Weed whacker) The work is best carried out towards the end of the winter.