the iberis family brings together a few dozen perennial, annual and biennial herbaceous plants, originating in southern Europe and western Asia. I. sempervirens is a perennial species, which forms large cushions about 30-40 cm tall; the leaves are small, oval, cuoiose, dark green; from the beginning of spring until late summer it produces large bunches of small flowers with four petals, yellow, white or pink. This plant is also called a rasp. They are commonly used to decorate flowerbeds and even rock gardens, being rather rustic plants. Their cultivation turns out to be rather simple, without the need to adopt particular cultivation techniques.
The flowering is prolonged by removing the withered flowers.
The stalk plants prefer the sunny positions where they can receive a few hours of direct light a day, since the positioning in the shaded areas inhibits the production of flowers. They are rather rustic and resistant specimens and do not particularly fear the lower temperatures, although, during the winter season it is good to cover the seedling with dry leaves or straw to prevent the root apparatus from freezing or from being ruined by winter drought and winds cold.
As for the correct supply of water, it is good to proceed with fairly regular watering, remembering that the stalk does not need large amounts of water, but it is better to avoid prolonged periods of drought. It is good to check that the soil does not allow the formation of water stagnations that are harmful to the health of the Iberis sempervirens and it is useful to let the soil dry well between one watering and another.
Provide fertilizer for flowering plants every 15-20 days from February to October so that the stem plants can grow more luxuriantly.
This variety of plants grows without problems in any soil as long as it is well drained; more vigorous plants and more abundant flowering are obtained by growing Iberis sempervirens in loose soil rich in organic matter.
When planting the stalk specimens, it is good to prepare a mixture of peat, organic substances, pumice and peat, so as to obtain a balanced mixture.
annual and biennial varieties belonging to this genus generally multiply by seed, at the end of winter; perennial varieties can be grown by seed, but daughter plants are not always identical to mother plants given their genetic variability, which is why they tend to propagate them by cuttings or by division of the tufts, during the autumn season.
Raspo, Iberis - Iberis sempervirens: Pests and diseases
The Iberis sempervirens suffer above all the excesses of water in the soil, for this reason they are easily affected by root rot or rottenness of the collar; for this reason it is essential to check that they are placed in a suitable substrate, which allows good water drainage, so as to avoid the formation of water stagnation.
For the rest, these plants are quite rustic and resistant and are not affected by pests and diseases.