My Zinnia Won't Germinate

Temperature

• Zinnia seeds need warmth to germinate; a temperature of around 75 degrees Fahrenheit is optimal. If you have sown seeds directly into the ground outside, germination may be delayed until the weather becomes warmer. Do not sow zinnia seeds outside until all danger of frost has passed. If seed has been planted in pots indoors in good quality potting compost, you can speed up germination by laying polythene over the pot (remove this as soon as seedlings are visible). Alternatively, place the pot on a warm windowsill, or on a warm surface such as a radiator shelf.

Water

• The process of germination starts when a seed absorbs water from its surroundings. Hence, if a seed does not have sufficient water, it will not germinate. Keep the potting medium moist at all times with regular watering. However, avoid over watering, as the seeds may rot and fail to germinate. Also, overwatering deprives the seeds of oxygen, another essential requirement for germination. Aim to keep the potting medium just moist and ensure that the zinnia seeds are not buried too deeply.

Seed Viability

• Old seed, or seed stored in unfavorable conditions, may not germinate even when the gardener provides all the essential requirements. Zinnia seeds may survive for between three and six years if they are stored in a cool, dark place. Check seed viability using a simple test: put some zinnia seeds on a moist paper towel, place them inside a plastic bag and store it in a warm place. Keep the paper moist and, if no signs of growth occur within a week, start again with a fresh batch of seed.

Growing Zinnias

• Zinnias are versatile plants, being equally at home in flower borders and in containers. They will thrive in well-drained, fertile soil in a sunny position. Zinnias attract butterflies into the garden and make good cut flowers for the home; cutting regularly will prolong flowering. Allow some flower heads to produce seed at the end of the season so you can collect your own seed and sow again the following year.