The genus Kalmia is represented by 7 species found in North America and one naturally growing in Cuba. In Poland, 3 species of kalmia are cultivated: wide-leaved K. latifolia, narrow-leaved K. angustifolia and multi-leaved K. polifolia.
In Poland, the most popular cultivation is the broad-leaved squid,a slowly growing shrub with always green, multi-season leaves. It grows up to 1.5-3 m in height, has a fairly compact, highly branched and irregular habit and bare, thin, slightly crooked shoots. White or slightly pink flowers develop in late May and early June. They have an original shape and are gathered 40-50 each in the top or side corymbs.There are a dozen or so varieties in cultivation that differ in the color of flowers - from white, through pink, to red (there are also two-color ones). The most popular are: 'Ostbo Red' with red flowers in the bud and pink after unfolding, 'Carousel' with dark purple red flowers, 'Nancy' with bright red flowers outside and dark red inside, 'Nipmuck' with white-pink flowers, 'Olympic Fire 'about pink and white flowers,' Olympic Wedding 'with pale pink flowers with a brown ring,' Pink Charm 'with flowers initially bright red and then dark red,' Quinnipiac 'with pink and white flowers and' Muras' with lilac flowers in bud and after unfolding pure white.
Calmia broad-leaved is characterized by very high frost resistance, tolerating frosts down to -29 ° C. It is also resistant to urban air pollution.
The second frequently cultivated species is the narrow-leaved squid,which grows up to 2 m in natural stands and is shorter in cultivation.It has very characteristic narrow leaves. In their corners are embedded red or red-purple flowers, which develop at the turn of May and June and are formed in the year preceding flowering. The following horticultural varieties are available: 'Hammonasset' with bluish pink flowers, 'Kenne-bago' with dark pink flowers, 'Royal Dwarf' with pink flowers, 'Rosea' with dark pink flowers and 'Rubra' with red-pink flowers . Most varieties grow very slowly, reaching about 80 cm after 10 years.
The last, lowest species is the multi-leaved squid,which in cultivation reaches 60 cm in height. Creates rarely branched shrubs with narrow leaves (4 cm long). The flowers are purple, gathered in multi-flower inflorescences at the tops of the shoots. They develop the earliest of all kalmia flowers, because at the turn of April and May.
Kalmy requires humus soils with organic matter, such as acid peat.They grow best in partially shaded positions, but with good soil conditions and systematic watering, they also feel great in a sunny position. They winter best in western Poland, while in other regions it is recommended to cover young plants during cold, snowless winters. In the garden, it is worth exposing the kalmas by planting them next to other shrubs from the heather family.
