dozens of species of perennial herbaceous plants belong to the genus polygala, widespread also in the Italian territory in the wild; in nurseries it is easier to find Polygala myrtifolia, also called polygal with myrtle leaves, a hybrid species obtained by crossing two species originating in southern Africa.
It has a roundish habit and very dense branches; the trunk is often multiple, covered by a greyish-colored bark. The leaves are evergreen, lanceolate, fairly coriaceous, of gray green color; they resemble the myrtle foliage, although they are larger in size. From spring to autumn the Polygala myrtifolia produces innumerable flowers, often gathered in bunches at the apex of the stems, of a pink-lilac color; in the form reminiscent of the flowers of the robinia, or of other fabacee. Adult shrubs can reach 150-280 cm in height. There are also dwarf varieties, with a very compact habit, which do not exceed 35-50 cm in height, and a white flower variety.
As regards exposure, it is advisable to place the Polygala myrtifolia in a sunny, or partially shaded, place; exposure to direct sunlight promotes flowering. These plants are native to areas with mild climate, so it is preferable to avoid exposing them during the winter, to periods of too intense and very prolonged cold; for this reason we tend to grow them in pots, so that they can be moved to a sheltered place in the event of prolonged frosts; It is also possible to place the myrtle-leaf polygal in the ground, taking care to find a place that is sunny and sheltered from the wind, if necessary during the winter a cloth in tnt is used to cover the foliage and repair it from the rigors of winter.
As for the amount of water to be supplied to the plant, from March to October it is necessary to water regularly, when the soil is well dry.
During the cold months the watering should be reduced if not suspended and the water should be supplied only in case of prolonged drought, during the mild days.
We avoid excesses and avoid keeping the soil too wet or soaked with water, as water stagnation is dangerous for the health of the plant. During the vegetative period, provide fertilizer for flowering plants, mixed with the water used for watering, every 15-20 days.
The Polygala myrtifolia prefer medium rich and soft, very well drained soils. It is advisable to repot the potted specimens every 2-3 years, providing new soil. It is advisable to use the soil ready for citrus fruits, or to prepare a mixture consisting of peat, little manure and a good quantity of pumice stone, so as to have a light and well drained soil that will not allow the formation of water stagnation .
The multiplication of polygal plants with myrtle leaves occurs by seed, in spring, or by cuttings, in summer, using the branches of the year that have not brought flowers.
Myrtle-leaf polygal - Polygala myrtifolia: Pests and diseases
Often the buds of this variety of plants are attacked by aphids; excessive watering or poorly draining soil can favor the development of root rot.
In the presence of parasites it is possible to intervene with targeted products that will effectively solve the problem.