Zinnias are mostly annual plants, popular because of the colourful, daisy-like flowers. Native to Mexico, there are 18 species and hundreds of cultivated forms, which are grown as annual bedding plants. Flowers come in vivid colours from red, orange and deep pink to green, with a lovely long flowering season from summer to the first frosts. Zinnias are perfect for filling gaps in the border and also work well in container displays. Long stemmed varieties make great cut flowers.
Zinnias thrive in hot, dry conditions, so grow them in well-drained soil in a sunny border. Single-flowered varieties are attractive to pollinating insects, particularly hoverflies.
Zinnias can be sown indoors from February until April, or sown outdoors directly into the soil in May. If sowing in trays or modules, make sure you use free-draining compost, so seedlings don’t suffer from dampness, and transplant seedlings as soon as they have a pair of true leaves.
It’s best to grow zinnias from fresh seed every year, also to ensure the colour mix of your chosen cultivar. But if you want to save seed for fun or thriftiness, you can select a few blooms to leave for harvesting. When the flowers have faded, you’ll find the seeds in just behind the base of the petals. Store the seeds in an airtight container until you are ready to sow as above in spring.
Zinnias can be prone to powdery mildews, mould and leaf spot, but don’t have any problems with pests.
Looking after zinnias
Pick zinnia flowers regularly to keep more coming, and apply liquid feed through the growing season.
Zinnia varieties to try
Zinnia tenuifolia ‘Red Spider’ – a compact zinnia, with wide-spaced, spidery petals, growing to a height of 60cm
Zinnia haageana ‘Soleado’ – known as the Mexican zinnia, this species has smaller leaves, making it more tolerant of hot dry conditions and winds. ‘Soleado’ bears masses of single orange flowers on strong, stems. Plants are easy to grow, resistant to rain and flower until the first frosts
Zinnia elegans ‘Queen Red Lime’ – the red flowers have lime-green tips to each petal. Grows to 60cm
Zinnia elegans ‘Envy’ – with unusual semi-double, lime green, dahlia-like blooms on long stems, this is more tolerant of shade than other zinnias. It also makes an excellent cut flower
Zinnia elegans ‘Orange King’ – a tall-growing zinnia, growing to 75cm, the flowers are showy, semi-double orange blooms. It’s ideal for using to fill gaps in the border, and also works well in container displays
Zinnia elegans ‘Purple Prince’ – a very tall-growing zinnia, up to 90cm, bearing striking double flowers in magenta with a lime green centre. It is perfect for growing in informal, naturalistic situations with grasses and other tall-growing annuals