Zinnia

Zinnia elegans

Engels: Zinnia

annualAsteraceae

Zinnia (Zinnia elegans) is a annual from the Asteraceae family that grows up to 90cm tall. This plant thrives in full sun and requires low maintenance. Blooms in summer and late summer and autumn with pink, orange, yellow, red, white flowers and attracts bees and butterflies.

Hoogte

40–90 cm

Breedte

25–40 cm

Zonligging

full sun

Waterbehoefte

moderate

Grondsoort

loam

Onderhoud

low maintenance

Bloeitijd

summer, late summer, autumn

Bloemkleuren

pink, orange, yellow, red, white

Ecologische waarde

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Verzorgingskalender

Taak	Jan	Feb	Mrt	Apr	Mei	Jun	Jul	Aug	Sep	Okt	Nov	Dec
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Care tips

Planting

Zinnias are half-hardy annuals that must be sown or planted after all risk of frost has passed, making May and June the ideal planting window in temperate Europe. They demand full sun and will produce weak, leggy growth and fewer flowers in shade. Choose a sheltered spot if possible, as their tall stems can be damaged by strong winds. Prepare the soil by digging in well-rotted compost or garden manure a few weeks before planting. Zinnias thrive in loam—fertile, well-drained soil that holds moisture without becoming waterlogged. If your soil is heavy clay, work in grit or sharp sand to improve drainage; if it's very sandy, add organic matter to boost water retention. Rake the bed to a fine tilth and remove any weeds. You can sow zinnia seed directly outdoors from mid-May onward, once soil temperatures reach around 15°C, or plant out young plants raised indoors or bought from a garden centre. Sow seed thinly, about 1 cm deep, in drills or scatter in patches, then thin seedlings to 30 cm apart once they have two or three true leaves. If planting out young plants, space them 30 cm apart in rows or groups. This spacing allows good air circulation, which helps prevent mildew, and gives each plant room to develop its full spread of 25–40 cm. Water gently but thoroughly after planting or sowing to settle the soil around roots or seeds. Avoid overhead watering if possible, as wet foliage encourages fungal disease. Apply a 5 cm layer of organic mulch around the base of plants once they're established to conserve moisture and suppress weeds, but keep mulch clear of stems to prevent rot.

Pruning

Zinnias do not require formal pruning in the traditional sense—there are no pruning months listed for this plant because you won't be cutting back woody growth or shaping a framework. However, regular deadheading and pinching are essential to keep plants flowering prolifically from summer through to the first frosts in autumn. Pinch out the growing tip of young plants when they reach about 15–20 cm tall. Use your finger and thumb to remove the top few centimetres of the main stem, just above a set of leaves. This encourages the plant to branch out lower down, producing a bushier shape and more flowering stems. Without pinching, zinnias tend to grow as a single tall stem with fewer blooms. Deadheading is the most important ongoing task. As soon as flowers fade, cut the stem back to just above a leaf joint or side shoot using clean secateurs or sharp scissors. This prevents the plant from setting seed, which signals the end of flowering, and redirects energy into producing new buds. Zinnias are prolific bloomers, so check plants two or three times a week during peak season. If you want to save seed, leave a few spent flowerheads on the plant at the end of the season and allow them to dry fully before harvesting. If plants become very tall or leggy mid-season, you can cut back stems by up to a third to encourage fresh, compact growth. Remove any yellowing or diseased leaves promptly to improve air circulation and reduce the risk of powdery mildew, which zinnias are prone to in humid conditions.

Maintenance

Zinnias have moderate water needs and perform best with consistent moisture, especially during hot, dry spells in summer. Water at the base of the plant rather than overhead to keep foliage dry and reduce the risk of powdery mildew and other fungal issues. In average summer weather, water once or twice a week; increase frequency during prolonged dry periods. Mulching helps retain soil moisture and keeps roots cool. Feed zinnias monthly during the growing season to support their long flowering period. Apply a balanced liquid fertiliser or a tomato feed (which is higher in potassium) in June and July as indicated by the feeding schedule. Too much nitrogen encourages leafy growth at the expense of flowers, so avoid high-nitrogen feeds once plants are established. A single application of slow-release granular fertiliser at planting time can also provide steady nutrition through the season. Zinnias are annuals and will not survive winter in any zone. They are killed by the first hard frost, usually in October or November. There is no need for overwintering protection—simply pull up spent plants in autumn and add them to the compost heap, or leave seed heads for birds if you wish. The main pest and disease issue is powdery mildew, which appears as white, dusty patches on leaves, particularly in late summer when nights are cooler and humidity is high. Improve air circulation by spacing plants correctly and removing affected leaves promptly. Avoid wetting foliage when watering. Aphids occasionally cluster on new growth; squash them by hand or spray with soapy water. Slugs may damage young seedlings in wet weather, so protect with organic slug pellets or barriers until plants are established.