Guide to Growing Zinnia
Profusion flower (above) and Common Zinnia (below).
Common species of Zinnia grown in the garden include Profusion flower and 'youth and old age'.
Zinnia by Photofarmer.
Purple Zinnia by Dendroica Cerulea. Both photographs under creative commons licence.
Quick Zinnia Growing Guide and Facts
Common Names: Zinnia: Rocky Mountain; Commonl Purple; Plains; Desert; Wild; Spinyleaf; Narrowleaf; Bush; Mexican.
Life Cycle: Half hardy annual.
Height: 6 to 40 inches (15 to 100 cm).
Native: Americas.
Growing Region: Zones 2 to 10.
Flowers: Summer until first frost.
Flower Details: White, yellow, yellow-green, cream, gold, burgundy, pink, red, purple, violet, orange. Multi, contrasting colours. Double ray florets; central disc. Dome. Papery.
Foliage: Green. Opposite. Linear through to Ovate.
Sow Outside: Cover seed. Following the last frost. Spacing 5 to 12 inches (12 to 30 cm).
Sow Inside: Germination time: one week to one month. Temperature 70 to 80°F (21 to 27°C). Seven or eight weeks in advance. Transplant outdoors following the last frost.
Requirements: Full sunlight or afternoon shade. Good drainage. Soil pH 6 to 7. Rich soil. Humus. Moist soil. Mix in manure. Regular watering to surrounding soil. Feed when transplanting. Feed at the start of flowering. Pinch tips.
How to grow Zinnia
If growing Zinnia from seed then sow outdoors following the last frost of spring; lightly cover the seed once sown. Zinnia should be spaced at 15 to 20 cm (small); 25 to 30 cm (medium) or 45 cm (large Zinnia species) apart.
Ideally grow Zinnia in a sunny area of the garden that gets an afternoon shade. These plants are able to grow in most soils of pH 6 to 7, but the soil should be enriched with manure for best results.
In cold areas it may be a good idea to start off Zinnia indoors first; do so about seven weeks in advance of transplanting. It should take about one to three weeks to germinate Zinnia at a temperature of 20 to 27 degrees Celsius. Transplant Zinnia outdoors just after the last possible frost of spring.
Caring for Zinnia
It is easy to look after Zinnia. Keep them well watered and feed them in the spring. Pinch back Zinnia to encourage branching; feed again once they start to flower. Remove (dead head) dying flowers.