Pampas grass (Cortaderia selloana) is one of the most conspicuous ornamental grasses, and in summer it is a delight with its large, white flower panicles. The complete German name of this species is actually American pampas grass, but since it is the most common of all species of pampas grass and the others are not available from us at all, it is usually simply called pampas grass, rarely also called silver pampas grass. Like the other 14 species of pampas grass, it comes from the tropical and temperate zones of South America and New Zealand, where it occurs on sand and alluvial soils. It belongs to the family of sweet grasses (Poaceae). In our latitudes it is not completely hardy and needs winter protection.
Appearance and growth
The leaves of the horst-forming grass are only about 80 centimetres high, but the flower panicles can reach heights of up to 250 centimetres. The individual leaves are grey-green, narrow, sharp-edged and wintergreen. They are quite stiff, but overhang in the upper part. Pampas grass reaches its peak during its flowering season in August and then well into the winter, when the magnificent flower panicles, which are visually reminiscent of feather duster, rise above the foliage. They can also be cut and dried are a beautiful ornament in tall vases and vessels. The best time to do this is before the flowers have completely opened. You should then dry the stalks in a shady place for two days before placing them in the vase.
Location and soil
The ideal location for a pampas grass is sunny and sheltered from the wind, as the long stalks fold slightly. Pampas grasses also prefer a nutrient-rich, deep and humus soil that does not dry out completely in summer and is permeable. Under no circumstances should the soil be too damp, as this will lead to rotting and sooner or later to the certain death of the grass. For this reason, you should not place the pampas grass in a place in the garden where moisture can easily collect, for example directly at the foot of a slope or slope.
Because of its stately appearance the pampas grass is an eye-catcher in every garden and its beauty is best shown off in its individual position. However, it can also be integrated into perennial plantations, although you should bear in mind the extent to which the ornamental grass will grow over the years. Diameters of well over one meter are not uncommon here. A particularly beautiful contrast is provided by perennials with filigree growth such as the magnificent candle (Gaura) or Patagonian verbena (Verbena bonariensis). Otherwise, when looking for suitable partners, you should pay particular attention to the fact that they have a similarly high nutrient requirement and the same site requirements as the pampas grass. These include many perennials that also prefer the living areas of bedding and open spaces.
Planting and care
The best planting time for pampas grasses is late spring, as they need warmth to grow and react very sensitively to low temperatures, especially in the first winter. Perfect is therefore a time after the ice saints. As the ornamental grass needs a nutrient-rich soil, you should work in some compost directly when planting if the soil is a bit leaner.
The pampas grass loves nutrient-rich soils and is one of the few ornamental grasses that – if the soil is too lean – must also be supplied with fertilizer. Only then can they develop their striking flowers in full splendour. Organic fertilizers such as compost, which is applied thinly every year at the beginning of the shoot, are best suited for this purpose. You can continue to fertilise the plant regularly until it flowers. Make sure, however, that it is not oversupplied, as this can lead to massive growth.
If your pampas grass is part of a perennial plantation, you can fertilize it together with the other plants. As a guideline, about 50 to 80 grams of organic fertiliser per square metre should be used and there should be several weeks between the individual fertilisations. An exception here are specimens planted in pots. They must be supplied with fertilizer every two weeks to balance the nutrients washed out by the irrigation water. In general, pampas grasses should only be watered sparingly, as they cope better with dryness than with wetness.
Since the Cortaderia’s own foliage serves as winter protection, you should only cut your pampas grass in late spring, as soon as no more severe frosts are to be expected. Wear working gloves for this work because of the sharp-edged leaves.
During pruning, all stalks are removed about 15 to 20 centimetres above the ground. In mild locations, the mop of leaves is wintergreen – it is therefore only cleaned with the fingers. Take care not to injure the new shoot.
In addition to the species, some varieties are also available on the market, which may differ significantly in height and flowering. Almost exclusively female plants are offered, since only they form the conspicuous blooms. The variety ‘Pumila’, which grows very compactly and whose flowers are only 150 centimetres high, is particularly common. Pumila’ is also the most robust pampas grass, although, like all species and varieties, it is sensitive to waterlogging and needs winter protection. The ‘Sunningdale Silver’ variety is considerably larger with growth heights of up to 250 centimetres. In this stately variety, the silver-white flower panicles are clearly above the mop of leaves. The ‘Rosea’ variety has very decorative flowers, because compared to most other varieties – as the name suggests – they are strikingly pink in colour. Patagonia’, on the other hand, is a delight with its reddish shimmering flower panicles.
The pampas grass originating from South America needs a winter shelter in our latitudes in order to overwinter and survive the cold season undamaged. However, it is not the low temperatures that cause the plant problems, but rather the winter wetness. Therefore it should never be pruned back in autumn, because the winter green foliage protects the heart of the plant. If it were missing, water could easily run into the cut straws and freeze there. Instead, the leaf head is tied together in autumn as soon as the first frosts threaten. That also looks very decorative. Then surround the plant with dry leaves and cover with brushwood.
Then wrap the grass with fleece – so it is well prepared for the winter. However, do not use foil for this, as liquid can easily collect underneath. And because there is no exchange of air, the plant begins to mold. Only when planting in a pot should you surround the tub with an insulating layer of bubble wrap. After the last strong frosts you can remove the winter protection again (March/April) and cut back the pampas grass as described above.
The easiest way to multiply pampas grass is by division. Although sowing is also possible, this type of propagation has some disadvantages. First of all, the seeds only germinate for a very short time and require temperatures of about 20 degrees Celsius. The majority of all pampas grasses on the market come from vegetative propagation and are therefore cloned. The reason for this is that the offspring then has the same characteristics as the mother plant. Since it has been cultivated in Europe for a long time, it has already adapted somewhat to our temperatures and is therefore harder to winter.
A further advantage of division is that because it is highly probable that a purchased specimen is a female, the offspring of divided plants will also be female and flower more beautifully. When sowing, however, the sex of the plant is uncertain. The best time to divide the plant is in late spring, as the offspring needs heat to grow. Simply cut a piece of the mother plant of any size and plant it in a pot to grow up. If you have the possibility to overwinter the young plants in a greenhouse, you can also share your pampas grass in autumn.
Diseases and pests
Pampas grasses are not susceptible to diseases and pests. Their biggest opponent is rather wetness in the root area. However, you can counteract this with an optimal location and appropriate winter protection. Occasionally, aphids may also infest the plant, resulting in sooty mildew.
I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.