Pratia pedunculata Alba

Pratia pedunculata or Isotoma fluviatilis Alba is the white form of a small perennial plant that proves to be very resistant once well established, capable of spreading enthusiastically into beautiful carpets. Its vegetation persists more or less in winter, and its spring flowering, with a thousand small white stars, illuminates and enlivens any setting, even in partially shaded areas. As it can tolerate occasional trampling and keep weeds in check, this plant can be used as an alternative to lawn, especially in difficult-to-mow or grassy areas, as well as to vegetate rocky slopes. Give it space to express itself and keep it away from fragile plants: in cool and light soil, where it thrives, Pratia pedunculata can smother its neighbours and become invasive!

Pratia pedunculata belongs to the bellflower family, it is native to Australia and New Zealand, where it thrives in moist and shady places. However, this perennial is well suited to our more continental climates: it is much more tolerant and resistant than the helxine with which it can still be associated, as it accepts both partial shade and full sun, and humus-rich soils as well as drier ones. This little plant even withstands frosts, down to -12/-15 °C (10.4/5 °F) at its coldest. The 'Alba' cultivar is distinguished by its white flowers.

This small ground cover plant is a formidable coloniser if the growing conditions are suitable. It develops surface branches that root at the nodes in contact with the ground, but also long underground stems, white and thicker than the above-ground stems, somewhat like couch grass. They form a network about 10 cm (4 in) deep, so that a new plant can emerge up to 1 m (3 ft) from the mother plant. Not exceeding 5 cm (2 in) in height, it rapidly spreads laterally, following the contours of the soil, over a theoretically unlimited area, forming an elegant flowering carpet in spring, usually in May-June. The flowering often continues from late July until autumn if the soil remains moist. The small star-shaped flowers of this Alba variety are composed of 5 pure white petals. They give way to small berries whose seeds readily self-seed. The foliage, evergreen in mild climates, disappears in winter if temperatures drop below -10 °C (-3.9 °F). If the soil is too dry, it becomes deciduous in summer until the return of rain. It consists of small leaves arranged alternately on the stems, bright green in colour, oblong in shape, with very slight dentate edges. The plant's vegetation cover also acts as a living mulch, protecting the soil from heavy rains and erosion, while preventing water from evaporating too quickly in dry weather.

It is between the slabs of a Japanese step or a pathway that Pratia pedunculata Alba is most original. It can advantageously replace helxine in sunny areas of the garden as well as in cold climates. Very adaptable, undemanding, and extremely robust, this vigorous ground cover also offers an excellent alternative to lawn in lightly trodden areas of the garden, whether sunny or shady, and even under large trees. It can also be used to cover unsightly embankments, discouraging weeds. However, it should not be planted in an alpine rockery with more delicate plants that it would quickly overwhelm and smother.

In shade, we recommend associating Pratia pedunculata with sturdy perennials to create a contemporary, minimalist scenography with a Japanese touch: for example, install ferns as a backdrop with a few epimediums, mixed with helxine.

In the sun, to dress an English garden pathway and make it more wild and romantic, plant Pratia pedunculata in front of a small bed composed of grasses, scabiosa, sage, echinaceas, and a few clumps of erigerons backed by tall roses such as the climbing Iceberg or Sombreuil, supported by chestnut stakes.

The exuberant Pratia pedunculata Alba also allows for the creation of lovely decorations on the terrace, with its flowering stems cascading from vases and flower pots, at the foot of larger plants.