<em>Zinnia</em>: sowing, planting, care

Description and botany

Native to scrub and desert prairies from southern United States to Mexico, Zinnia is an annual herbaceous plant of family Asteraceae close to daisies and cosmos.

It is a non-hardy plant grown in gardens as an annual flower because of its frost-tender character.

Genus comprises 20 species, the most common and oldest being Zinnia elegans or elegant Zinnia. Zinnia tenuifolia, a botanical species, and Zinnia angustifolia or Mexican Zinnia are more unusual. There are nearly a hundred hybrids divided into varieties in a wide range of colours, pastel or bright. They also differ in height (dwarf zinnias, tall zinnias), and in diameter and shape of their single, semi-double or very double flowers.

With rather rapid growth, Zinnia forms a vigorous, bushy, compact ramified clump, more or less tall depending on variety. Dwarf varieties do not exceed 20 cm while tall zinnias can reach 90 cm to 1 m in height.

From this bushy, erect stump emerge rigid stems, angled or rounded and well ramified bearing rough, slightly downy foliage of a lovely medium to pale green. Opposite, linear, ovate or elliptical leaves measure 2 to 8 cm and are pointed.

With its pubescent texture, this deciduous vegetation provides a setting for Zinnia’s abundant flowering. Flowering starts in June and continues until first frosts.

Flowers are solitary heads borne at tip of long upright stems. Zinnia flower has a very distinctive character. These solitary head inflorescences are formed of one or several rows of ligulate petals radiating around a centre that emits tiny ligules with pistils more or less apparent.

Some zinnia flowers: Zinnia ‘Queen Red Lime’, Zinnia ‘Profusion Double White’, Zinnia elegans ‘Mazurkia’, Zinnia peruviana, Zinnia ‘Double Zahara Raspberry’

Flower diameter varies from 2 cm to 12 cm. Their sometimes complex structure also varies with variety; single, semi-double or very double pompon. Shape of ligules also differs by cultivar: spatulate, more or less tubular, or flat.

Some zinnias bear long rolled and pointed petals that form a pompon-like centre with cactus-flower appearance, others display only a single crown of petals around a central disk like a simple daisy or a cosmos, others form slightly flattened pompons reminiscent of small dahlias.

Accordingly, zinnia flowers are classified as cactus-flowered, dahlia-flowered, scabious-flowered, chrysanthemum-flowered…

Zinnia is much appreciated for its striking, sometimes exuberant colours. Its flowers show the widest variety of colours, pastel or vivid, plain or surprising bicolours. They declinate into an endless palette of colours ranging from blazing orange to cherry red, from pure white to golden yellow, from purple to smoky pink, including the chartreuse green of Zinnia ‘Envy’.

Zinnia elegans ‘Envy Double’ with a beautiful chartreuse green

Slightly scented, flowers give off a waxy perfume reminiscent of floor polish, and also keep very well in summer bouquets.

Nectariferous, this abundant flowering delights bees and butterflies.

Vigorous and floriferous, Zinnia is within reach of all gardeners. It dislikes coolness and shade and likes sunny, warm exposure, in any ordinary, well-drained soil. Versatile, it is planted in borders, in beds where it creates splashes of colour or in the vegetable garden, between vegetable rows. It can also be grown in pots to flower a terrace in summer.

Main species and varieties

Les plus populaires

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Autre zinnia intéressant

Zinnia Zahara Double White

Sturdy, compact zinnia, highly disease-resistant, from 'Profusion' series. To grow equally well in borders and flowering containers.

• Flowering time August to December
• Height at maturity 40 cm

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Zinnia Persian Carpet Seeds

This selection brings together small varieties with bicoloured flowers. Perfect for a warm-coloured theme in a sunny border.

• Flowering time August to October
• Height at maturity 35 cm

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Zinnia zahara Double Fire

This variety proves very disease-resistant and shows excellent tolerance to summer drought and humid climates. Ideal for country-style borders and atop low walls.

• Flowering time August to December
• Height at maturity 35 cm

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Zinnia elegans Burpeeana Chrysanthemum Flowered Mixed Seeds

Its large, double, rolled-petal flowers resemble Chrysanthemums. A mix of varieties ideal for use in centre or at back of a border.

• Flowering time August to November
• Height at maturity 90 cm

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Zinnia elegans Polar Bear Seeds

Superb large Zinnia variety with huge flowers. Adds a beautiful touch of elegance to a border. Also superb in bouquets.

• Flowering time August to November
• Height at maturity 75 cm

See the product sheet

Zinnia elegans Purple Prince Seeds

Excellent large Zinnia variety with flowers reminiscent of dahlias. Vigorous and floriferous, splendid in borders and also in bouquets.

• Flowering time August to November
• Height at maturity 75 cm

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Zinnia elegans Giant Double Mixed Seeds

Variety of large Zinnias with large double heads. Easily paired at heart of a colourful border or in vegetable garden.

• Flowering time July to September
• Height at maturity 75 cm

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Zinnia tenuifolia Red Spider Seeds

Annual zinnia with delicate spider-like flowers! Will enliven borders, beds and bouquets until autumn.

• Flowering time August to November
• Height at maturity 60 cm

See the product sheet

Planting zinnias

Where to plant zinnia?

Frost-tender, Zinnia does not survive winter in our climates. That is why we grow it as an annual in our gardens. It is born and dies in the same year, yet still has time to enchant our gardens with its endless flowering!

Easy to grow, Zinnia will be happy and floriferous only in a warm, very sunny position, showing tolerance to summer drought. It thrives in regions with hot, torrid summers and can be more capricious in regions with cool or overly rainy summers; it is intolerant of coolness, shade and prolonged rainy periods.

While it adapts to any good garden soil, even gravelly, it will be more vigorous in fertile soil, rich in humus and well drained.

It is a very versatile annual plant that imposes itself in country-style beds, even in poor and neglected areas of the garden. Dwarf zinnias are ideal for colouring regular borders, forming tapetum of flowers in very sunny rockeries right up to the onset of winter or flowering pots on the patio in summer. Large zinnias slip into medium or back of beds or remain neatly in rows in the vegetable plot.

When to plant zinnias?

Planting of Zinnias as plug plants is done from March to May, once frosts are no longer a risk.

How to plant zinnias?

In open ground

Pot on the Zinnia plug plants on receipt in pots and keep them under cover in a warm, bright place at a temperature above 14 °C for a few weeks. Wait until mid-May before planting them in open ground.

Plant in groups at a rate of 5 buckets per m2, respecting a spacing of 35 to 40 cm for tall varieties and 25 cm for dwarf zinnias.

• Dig over soil well to loosen it
• Dig a hole 2 to 3 times wider than the plug plant
• Spread gravel or clay balls at the bottom of the planting hole
• Place the plug plant in the centre of the hole, the collar at soil level
• Backfill with garden soil mixed with potting compost for flowering plants
• Firm down with the foot
• Water generously
• Mulch the base of the zinnia to retain coolness

More advice on how to plant our annual plants as plug plants on our blog!

Planting zinnia in pots

Zinnia performs very well in pots, window boxes or planters positioned in full sun.

• Make a good bed of gravel or clay balls at the bottom of the pot
• Set the plug plant in a good potting compost for flowering plants
• Water generously at planting

When and how to sow zinnias

Successful sowing of Zinnias under cover

Zinnia is tender and should be sown from March to April under warm cover at a minimum temperature of 15°C. Pot on young plants in April, May or even June depending on region. Discover our tips and tricks to succeed in sowing annual seeds on our blog!

• Sow zinnia seeds in a seed tray in a good seed compost
• Cover seeds lightly with compost kept slightly moist
• Maintain 15–25°C during germination
• When young plants reach 3-leaf stage, pot them into buckets
• Plant young plants out in garden once risk of frost has passed and outdoor temperature is above 18°C
• Space plants about 30 cm apart
• Water to ensure establishment

Faded zinnia flower

In open ground

Stagger sowings for longer flowering.

• After frosts, in May, in well-drained, warmed soil, sow thinly by broadcasting without burying seeds too deeply: cover them with only 3 mm of compost
• Keep soil moist until seed germination
• After emergence, within 7–14 days, thin the ranks leaving about 30 cm between each young plant

Care and maintenance

Zinnia is truly the trouble-free annual, easy to grow and care for.

Its water needs are quite low. However, in periods of high heat, do not skimp on regular watering at the base of the plant rather than on the foliage: zinnia is susceptible to powdery mildew. Mulch in June to keep roots cool.

Water potted zinnias more regularly as soon as surface soil is dry and apply fertiliser for flowering plants to support flowering.

Cut off faded flowers on zinnias to encourage new flowers and extend flowering.

Pinch out the main stem as soon as flowering starts to encourage branching.

Pull up all plants before hard frosts.

Possible diseases and pests

Le Zinnia est bien résistant, il est toutefois fréquemment powdery mildew. Arrosez au pied de la plant without ever wetting foliage.

Discover our solutions to prevent powdery mildew.

Les slugs sont également très friandes des jeunes shoots, inspirez-vous de our tips to control these unwelcome visitors.

Slug damage on zinnias

Propagation

Zinnia multiplies exclusively by sowing (see above “when and how to sow zinnia seeds” properly). If you have harvested and kept zinnia seeds from dried flowers, you can sow them the following year. Be aware, however, that it is very likely you will not get the same flowers as the parent plant. Indeed, Zinnias are a symbol of inconstancy and genetics (Mendel’s laws) are responsible for this, as is cross-pollination. Thus, from one generation to the next, flowers can be completely different if you harvest your own seeds. Alternatively, choose from our unique collection of annual zinnia seeds.

Companion planting zinnias in the garden

Zinnia is a bright annual plant with colours, sometimes very vivid and verging on garish, that naturally finds its place in natural gardens and country gardens. It works equally well in bedding schemes or at the front of a border and in the vegetable garden among vegetable plants. Depending on variety, it will bring either a fresh, ordered touch or a warm, exuberant note to summer scenes and pairs easily with many annuals or summer-flowering perennials.

A romantic, country-style pairing idea: pink zinnia such as ‘Miss Willmott’, ‘Art Deco’ or ‘Double Zahara Strawberry’, Hordeum jubatum and white umbels of Daucus carota (or pink umbels with ‘Dara’)

In the foreground of a mixed-border, it happily combines with coleus, lonas annua, snapdragons and wallflowers, all equally easy to grow.

In the heart of a colourful border, mix tall zinnias with dahlias, chrysanthemums, gaillardias, bidens, coreopsis, Rudbeckias, echinaceas for flowering until first frosts, and foliage-contrasting sedges.

In a large sunny bed, combine zinnias with moss verbenas, Eryngium and Buenos-Aires verbena.

Tone down the colours of the boldest varieties by pairing them with other annual plants in softer shades, such as nigellas, flowering tobaccos, cosmos, ornamental carrot, white gauras or Ammi majus, and place small groups amid grey or contrasting foliage of artemisias or sedges.

Zinnia flowers will also impose themselves in a Catalan-inspired border in warm tones with Echinaceas, Cannas, tritomas, achilleas, bidens and gaillardias. Light grasses such as Stipa tenuifolia, Miscanthus or Eragrostis trichoides will soften the heat and provide contrast to the somewhat upright habit of this annual.

An example of a warm-toned scheme: red zinnia (‘Profusion Double Hot Cherry’, ‘Profusion Double Fire’), Canna (for example ‘Durban’), Hemerocallis ‘Citrina’, Dahlia ‘Catherine Deneuve’ and you can complete the scheme with Iberis ‘Absolutely Amethyst’, Salvia farinacea ‘Victoria’ and red annual verbenas

In the vegetable garden, a few rows of zinnias will mix well with panicle amaranths, purple beetroot, colourful cardoons of chard leaves, marigolds, dahlias and nasturtiums.

In pots, combine zinnia flowers with petunias and surfinias.