How to Grow and Care for Primula Polyantha
Dahlias originate from the highlands of Mexico. They are not frost-tolerant and cannot stand intense summer heat; in regions with cool summers and large day-night temperature differences, they grow and bloom well. During the growing season they have strict water requirements: they cannot tolerate drought but also dislike waterlogged soil, and they prefer sandy loam rich in humus. They like full sunlight, with slight shading during intense summer light.
Propagation: Commonly propagated by division, cuttings and sowing. For division, be careful to keep the sprouting buds on the old stems at the root crown. For cuttings, March to April gives the highest survival rate. For sowing, sow in pots in spring, and the seedlings can bloom in the same year.
Cultivation: Plant in the ground in early spring, and set up supports during the growing season to prevent wind damage. Pinch the tops at the seedling stage to encourage branching, making plants compact and free-flowering. Water promptly in summer, apply a top dressing once every ten days, and remove withered flowers promptly during the flowering period to help new flower shoots form. In autumn and winter, cut back the branches and leaves, dig up the tuberous roots, and store them indoors in sand for the winter. For pot cultivation, choose dwarf varieties, strengthen fertilizer and water management at the seedling stage, and during bud formation remove the side buds and keep the terminal bud, which gives thick stems and large flowers.
Pests and diseases: Aphids, red spider mites, powdery mildew and brown spot often occur in summer. Ensure good ventilation; when pests are found, control them with 40% dicofol emulsifiable concentrate at 1000 times dilution, and when diseases appear, spray with 50% thiophanate wettable powder at 1000 times dilution.
Uses: Dahlias have a very long flowering period and beautiful flower forms, including single, star-shaped, ball-shaped, peony-shaped and pasqueflower-shaped. Flower colors are rich, including red, orange, yellow, white, light red, deep purple and speckled gold. They are suitable for flower beds, flower borders, pot cultivation or garden planting, and can also be used as cut flowers.