How to grow zinnias
Find out all you need to know about growing zinnias, in this practical Grow Guide.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow | yes | yes | ||||||||||
| Plant | yes | yes | ||||||||||
| Flowers | yes | yes | yes | yes |
Zinnias are mostly annuals (plants that complete their lifecycle in a year), popular because of the colourful, daisy-like flowers. There are a few perennial species, but they are generally not grown as ornamentals. The zinnia plants we grow in the UK do not come back every year.
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.
Where to plant zinnias
Grow zinnias in well-drained soil in a sunny, sheltered spot. They do best in warm weather, but also need regular watering. Zinnias are suitable for cutting patches, borders and for growing in containers. If you don’t have free-draining soil in full sun or you have problems with slugs and snails eating your seedlings, your zinnias are likely to do better in pots rather than in the ground. Choose compact varieties for containers, such as ‘Pinwheel’ and ‘Profusion Mixed’ that won’t need staking.
How to plant zinnias
You can sow zinnia seed indoors from February until April, or sow zinnias 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.
How to care for zinnias
Pick zinnia flowers regularly to keep more coming, and apply liquid feed through the growing season. Taller varieties of zinnia are likely to benefit from staking before they become too tall. If you're not picking flowers for the house, cut off fading flowers regularly to encourage plants to produce more blooms.
How to propagate zinnias
It's best to sow fresh zinnia seed every year. This also ensures 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.
How to take zinnia cuttings
It's possible to take cuttings from zinnias to produce new plants, but it's not really worth doing as they're so easily sown from seed.
Pests and diseases
Zinnias can be prone to powdery mildews, mould and leaf spot, but don't have any problems with pests. Minimise the risk of fungal disease by ensuring the leaves don’t get wet when you water the soil at the base of the plant.
Advice on buying zinnias
- Zinnia flower seeds are available in individual named varieties across a range of different colours
- Make sure you choose the right flower colour and height for your display, as these can vary depending on variety
Where to buy zinnia seeds and seedlings online
Zinnia varieties to try
Zinnia elegans 'Queen Red Lime'
Zinnia elegans is a popular species with many different varieties. The red flowers of Zinnia elegans 'Queen Red Lime' have lime-green tips to each petal.
Height x Spread: 60cm x 20cm
Zinnia elegans ‘Envy'
Zinnia elegans ‘Envy' has unusual semi-double, lime green, dahlia-like blooms on long stems. It's more tolerant of shade than other zinnias and also makes an excellent cut flower.
H x S: 60cm x 30cm
Zinnia elegans 'Orange King'
Zinnia elegans 'Orange King' is a tall-growing zinnia. 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.
H x S: 75cm x 20cm
Zinnia elegans ‘Purple Prince’
This very tall-growing zinnia, bears striking double flowers in magenta with a lime green centre. Zinnia elegans ‘Purple Prince’ is perfect for growing in informal, naturalistic situations with grasses and other tall-growing annuals.
H x S: 90cm x 20cm
Frequently asked questions
Do zinnias come back every year?
In the UK, zinnias do not come back every year. The zinnias we grow are annual plants, so they complete their life cycle in one year.
How do I get my zinnias to flower?
Zinnias bloom from July until the first frosts. To get zinnias to flower, feed with a high potash liquid feed every fortnight and make sure plants are watered regularly. Deadheading spent flowers encourages the production of more blooms and extends the flowering season.
