There’s no mistaking the colour and stature of annual Zinnias. Plant Zinnia seeds in average, well-drained garden soil, but dig in a generous amount of well-rotted manure the previous fall. Pinch off growing tips early in the season for bushier growth. Water regularly, keeping leaves as dry as possible. Deadhead regularly. Feed once in early spring, and again once flowering has begun. Continue reading below for tips on how to grow Zinnia from seed.
Season & Zone
Exposure: Full sun
Direct sow after last frost. Zinnias don’t transplant well, but can be started indoors, if necessary, in peat or coir pots, 6-8 weeks before planting out. Maintain a soil temperature of 21-26°C (70-80°F). Seeds should germinate in 5-24 days.
Just cover Zinnia seeds, and aim for a final spacing of 25-30cm (10-12″) between plants.
Depending on the variety, it takes about two months after sowing for the first flowers to appear. Take regular cuttings of Zinnia stems to enjoy indoors, starting mid-summer right into the fall. Cutting encourages the production of new flowers and seems to stimulate the plants for greater vigour. Watch for signs of powdery mildew on the leaves, usually in late summer. Try to avoid overhead watering to prevent mildew.