For this type of vegetation, daily care also consists mainly of removing unwanted species or intervening by allowing them to go to seed or not, or to proliferate, by planting and replanting and, last but not least, monitoring its development. Open grounds with refined species such as thyme, pinks, stonecrops, sundew, bog asphodel or Viola calaminaria require a lot of work. Less intensive is the maintenance of species with denser foliage and greater competition power, such as creeping jenny, bugle, yellow corydalis, meadow sage, marjoram and common rock rose. Requiring only extensive maintenance are densely leafy, vigorous species such as meadow cranesbill, common bistort, marsh marigold, purple loosestrife, crown vetch and dark mullein. In contrast to shade-tolerant field layers, which generally need little care, vegetations in full light require more maintenance. The limiting factor of shade obviously is an advantage for the park manager. When there is a shift of light-requiring species towards more shadetolerant ones, the essence of daily maintenance changes as well. Weeding out unwanted species becomes less important, the workload shifts towards keeping in check desired plants trying to dominate the lighter, more open spaces. Lily of the valley, Solomon’s seal and periwinkle have to be kept at bay in order to prevent them from pushing out the light- requiring species. The planting as a whole degenerates, foliage canopies intertwine and become less and less attractive.
Annuals and biennials such as centaury, trailing St John’s wort, petrorhagia and Deptford pink require open spaces with bare soils, as they have little competitive power. It is necessary to remove Sagina procumbens, mosses and other low-growing species forming dense mats, in order for the former to find growing opportunities in specific spots. Scratching open the fringes of paths creates new opportunities for species such as pale St John’s wort, purging flax and grass of Parnassus. By combining species of comparable competitive capacity, an acceptable balance can be maintained, making the vegetation stable for a long time. Plants with corms and rhizomes usually need to be able to move. If they are forced to stay in the same spot for long they will react by flowering less freely, and will show decreased vitality. In a flower meadow from which grasses are excluded, it is left to the competitive species to arrange themselves. The only weeding is of grasses and other species adjudged to be weeds. Great burnet, meadow cranesbill, agrimony, common ragwort, purple knapweed and ox-eye daisy may provide splendid displays with an abundance of flowers. Whenever necessary, the over-dominant species are restrained in places by surface cultivation, thus creating growing spots for other species. In this manner, one can maintain the flower meadow for many years. If, however, one does not intervene, the number of species will be reduced as a result of the—dominance of one or just a few species.
Open spots with lots of light, especially those in full sun, offer many opportunities for herbaceous vegetations with many aspects. One can discern a number of main vegetation types:
– pioneer vegetation
– half-open vegetation
– closed vegetation
– woodland fringe vegetation.
The boundaries of these vegetation types, generally, are rather diffuse, with all sort of transitions and mixed forms. It is often a certain degree of interweaving that makes these communities attractive, it is a substantial element of their nature and atmosphere. Not only should the manager have a keen eye and sense for the meaning and the use of these vegetation types, he also needs to have an understanding of their evolution and progress. He needs to read, as it were, what is desirable and how he should act in the given circumstances, tuning his reactions to the development of a specific plant community. The manager also needs to be able to recognise the following stages and to act accordingly when necessary: a starting point, an optimum, continuing progress and, finally, decay.
Very refined and subtle combinations of species that are partly ground covering, partly of a more upright habit, may provide a perfect background for specimen plants such as ferns, small brooms or wild roses. A combination of early flowering Lychnis floscuculi with low-creeping plants like thyme, sedum, dianthus, Veronica—with Pulsatilla vulgaris or Dactylorhiza praetermissa as special elements—but also Dianthus deltoides, Hypericum pulchrum with Arnica montana and Gentiana cruciata, are a few examples. Ajuga reptans as a dark-green tapestry against which its own blue candles form a beautiful contrast, or Lysimachia nummularia in combination with the numerous blue button flowers of Succisa pratensis, reminding one of a swarm of insects. High-impact vegetations may also consist of species with conspicuously coloured flowers, carried in abundance—for example Salvia verticillata and Helianthemum nummularium or Origanum vulgare, with some solitary plants of Verbascum nigrum.
With more competitive species, strong effects can be obtained by using them en masse. Polygonum bistorta, Geranium pratense, Agrimonia procera and Sanguisorba officinalis are ideal for use in masses. Atmospheric effects may be obtained by bringing together species with related flower colours. Yellow and blue-purple-pink combinations provide strong contrasts. More harmonious contrasts can also be achieved, for example the yellow shades of Hypericum perforatum, Verbascum nigrum, Senecio erucifollius and
Genista germanica blend into a splendid composition. The blue, purple and pink shades of Campanula rapunculoides, Knautia arvensis, Scabiosa columbaria, Centaurea pratensis, Origanum vulgare, Coronilla varia and Malva moschata have an equally splendid effect. One may increase the impact by letting the effects of the open spaces spread into the woodland verges, using, for example, Senecio nemorensis, Aconitum lycoctonum and Aristolochia clematitis for the yellow shades and Campanula trachelium, Leonurus cardiaca and Malva alcea for the blue, purple and pink shades.