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

Description and botany

Originating from scrub and desert prairies of the southern United States through to Mexico, Zinnia is an annual herbaceous plant of the family Asteraceae, related to daisies and cosmos.

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

The 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 singular. There are nearly a hundred hybrids split into varieties in a wide range of colours, pastel or vivid. They also differ in height (dwarf zinnias, tall zinnias), and in the diameter and shape of their flowers, single, semi-double or very double.

With fairly rapid growth, Zinnia forms a vigorous ramified, bushy and compact 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, upright stump emerge rigid, angular or rounded and well-ramified stems bearing a rough, slightly downy foliage of attractive medium to pale green. Opposite, linear, ovate or elliptical leaves measure 2 to 8 cm and are pointed.

With its pubescent texture, this deciduous foliage forms a foil for Zinnia’s generous flowering. Flowering starts in June and continues until first frosts.

Flowers are solitary heads borne at the end of long erect stems. Zinnia’s flower has a very strong personality. These inflorescences, solitary heads, are formed of one or several ranks of radiating ligulate petals around a centre that reveals tiny tubular florets with more or less visible pistils.

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

Flower diameter ranges from 2 cm to 12 cm. Their sometimes complex structure also varies by variety; single, semi-double or pompon-like very double. Ligule shape also differs between cultivars: spatulate, more or less tubular, or flat.

Some zinnias bear long rolled, pointed petals forming a fluffy pompon-like centre , others display a single crown of petals around a central disc like a simple daisy or a cosmos, while others form slightly flattened pompons evoking small dahlias.

Thus, zinnia flowers fall into classifications: cactus-flowered zinnias, dahlia-flowered, scabious-flowered, chrysanthemum-flowered…

Zinnia is highly prized for its bright, sometimes even exuberant colours. Its flowers show the widest variety of hues, pastel or vivid, plain or surprising bicolours. They come in an endless palette from flaming 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’ in a lovely chartreuse green

Slightly scented, flowers give off a waxy fragrance somewhat like floor polish, and also keep very well in summer bouquets.

Nectariforous, this abundant flowering delights bees and butterflies.

Vigorous and floriferous, Zinnia is within reach of every gardener. It dislikes coolness and shade and thrives in sun in a warm exposure, in any ordinary, well-drained soil. Versatile, it is planted in borders, in flowerbeds where it creates splashes of colour, or in the vegetable garden between vegetable rows. It can also be grown in pots to adorn the patio in summer.

Main species and varieties

Most popular

Our favourites

Another interesting zinnia

Zinnia Zahara Double White

Hardy little compact zinnia, very disease-resistant, from 'Profusion' series. To grow in both borders and flowering containers.

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

See the product sheet

Zinnia Persian Carpet Seeds

This selection gathers small varieties with bicoloured flowers. Perfect for a warm-coloured scheme in a sunny border.

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

See the product sheet

Zinnia zahara Double Fire

This variety proves very disease-resistant and shows perfect tolerance to summer drought and humid climates. Excels in cottage-style borders and on top of walls.

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

See the product sheet

Zinnia elegans Burpeeana Chrysanthemum Flowered Mixed Seeds

Large double flowers with rolled petals resemble chrysanthemums. A variety mix ideal for use in middle or back of border.

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

See the product sheet

Zinnia elegans Polar Bear Seeds

Superb large zinnia variety with huge flowers. Brings elegant touch to border. Also excellent 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 dahlia-like flowers. Vigorous and floriferous, in borders also splendid in bouquets.

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

See the product sheet

Zinnia elegans Giant Double Mixed Seeds

Large zinnia variety with large double heads. Easily paired at heart of colourful border or in vegetable garden.

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

See the product sheet

Zinnia tenuifolia Red Spider Seeds

Annual zinnia with delicate spider-like flowers! Will brighten borders, edgings 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-sensitive, Zinnia does not survive winter in our climate. That is why it is grown as an annual in our gardens. It is born and dies within the same year, yet still gives us time to enchant 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, scorching summers but can be more capricious in regions with cool or overly wet summers; it dislikes coolness, shade and long rainy periods.

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

This is a very versatile annual plant that imposes itself in country-style beds, even in the ungrateful, neglected parts of the garden. Dwarf zinnias are ideal to colour regular borders, form tapetum of flowers in very sunny rockeries right up to winter limits or flower pots on the terrace in summer. Tall zinnias slip into middle or back of borders or stay neatly in rows in the vegetable patch.

When to plant zinnias?

Planting Zinnias in plug plants is done from March to May when frosts are no longer a risk.

How to plant zinnias?

In open ground

Pot on Zinnia plug plants on receipt into 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, spacing 35 to 40 cm for tall varieties and 25 cm for dwarf zinnias.

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

More advice on how to plant our annuals in plug plants on our blog!

Planting Zinnia in pots

Zinnia does very well in pots, window boxes or large containers placed in full sun.

• Make a good bed of gravel or clay balls at bottom of pot
• Set plug plant into 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. Prick out 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 seed tray in good sowing compost
• Cover seeds lightly with compost kept slightly moist
• Maintain 15–25°C during emergence
• When young plants reach three-leaf stage, prick out into buckets
• Plant out young plants in garden once risk of frost has passed and when outside temperature is above 18°C
• Space young 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 lightly with 3 mm of compost
• Keep soil moist until seeds germinate
• After emergence, between 7 and 14 days, thin out ranks leaving about 30 cm between each young plant

Care and maintenance

Zinnia is truly a hassle-free annual plant, easy to grow and care for.

Water needs are fairly low. However, in case of very hot weather, don’t skimp on regular watering at the base of the plant and not on the foliage: zinnia is sensitive to powdery mildew. Apply mulch in June to keep roots cool.

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

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

Pinch out main stem as flowering begins to encourage branching.

Pull everything up before severe frosts.

Potential diseases and pests

Zinnia is fairly hardy, but often prone to powdery mildew. Water at base of plant without ever wetting foliage.

Discover our solutions to combat powdery mildew as preventive measures.

Slugs are also very fond of young shoots, take inspiration from our advice to combat these pests.

Slug damage on zinnias

Propagation

Zinnia is propagated exclusively by sowing (see above “when and how to sow zinnia seeds“). If you have harvested and stored zinnia seeds from your 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 the cause, as is cross-pollination. Thus, from one generation to the next, the flowers can be totally different if you harvest your own seeds. Alternatively, choose from our unique annual zinnia seeds.

Pairing zinnias in the garden

Le Zinnia is a bright annual plant with colours sometimes very vivid, bordering on garish, that naturally asserts itself in naturalistic gardens and country gardens. It is equally appreciated planted in mixed beds or at the front of a border as well as in the vegetable patch among young plants of vegetables. Depending on variety, it will bring a fresh, ordered touch or a warm, exuberant note to summer scenes and pairs easily with many annuals or perennials with summer flowering.

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 pairs happily with coleus, Lonas annua, snapdragons and wallflowers, all equally easy plants to grow.

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

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

Tone down colours of the most fiery varieties by pairing them with other annual plants in softer hues, such as nigellas, flowering tobaccos, cosmos, ornamental carrot, white gauras or Ammi majus, placing small touches amid grey or contrasting foliage of artemisia or sedges.

Zinnia flowers will easily impose themselves in a Catalan-inspired warm-toned border with Echinaceas, Cannas, tritomas, Achilleas, bidens, gaillardias. Light grasses such as Stipa tenuifolia, Miscanthus or Eragrostis trichoides will calm the blaze and bring softness in counterpoint to the somewhat rigid habit of this annual.

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

In the vegetable patch, a few rows of zinnias will mingle with panicle amaranths, purple beetroot, the colourful chard leaves of poirées, marigolds, dahlias and nasturtiums.

In containers, pair zinnia flowers with petunias and surfinias.