Influence of substrate pH on the growth and flowering of Mandevilla Lindl. Sundaville® ‘Pretty Red’

Sundaville is the brand name of a new collection of cultivars of the genus Mandevilla (syn. Dipladenia), with the potential to become a leading vine in the world horticultural market. The research was carried out in order to analyse the growth of Sundaville ‘Pretty Red’ at different values of substrate pH (4.0, 4.7, 5.3 and 5.5). The study shows that flowers appeared after more than six months irrespective of soil conditions. Plants cultivated at pH 4.0 had the longest leaves, but at the highest substrate pH the widest leaf laminae were observed. Regardless of the substrate pH, the diameter of a single flower remained the same. Plants cultivated at a pH lower than 5.0 produced more flower buds and more flowers in comparison with the plants exposed to the higher pH. Moreover, pH < 5.0 positively affected the number of stems. The soil pH did not only affect the growth, but also the health of the plants. The lowest pH level (4.0) caused adverse changes to the leaves.