Zinnias add a variety of colours to your Prairie garden (2024)

The brilliant colours of a well-designed annual flowerbed can be awe-inspiring.

Once those flowers start to bloom in early summer, the show usually carries right through to a killing frost in fall. There are many annual flowers that perform well in the Prairie garden, but one of my favourites is the zinnia.

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Zinnias (Zinnia elegans and Zinnia augustifolia) are part of the Asteraceae family of plants, also known as the daisy or sunflower group. One of the most obvious characteristics of this plant family is the composite flower heads, which appear as one flower but are composed of many small flowers called disc flowers that may or may not also have ray florets. These ray florets occur as colourful petals.

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Zinnias have disc flowers in the centre of the head that are usually surrounded by colourful ray florets along the circumference. Some zinnia inflorescences are rather simple with tight, button-like, colourful, centre-of-disc flowers surrounded by a single row of ray florets (like a daisy). Or they can be made up of several rows of ray florets surrounding a small area of disc flowers (like a dahlia). The inflorescences can also vary in size from small pom-poms to large (10- to 15-centimetres in diameter).

Some zinnias can have speckled or streaked petals and some inflorescences are multi-coloured.

Originating in the southwestern part of Mexico near Tixtla de Guerrero, zinnias naturally prefer warm and sunny locations. Although they can withstand some drought, zinnias should be watered regularly.

Zinnias that suffer extended periods of drought will not recover well. Alternatively, zinnias tend to be infected by powdery mildew and botrytis if overwatered or grown in shady, cool conditions. If you notice the bottom leaves on your zinnias starting to wilt and die back, remove these infected plants immediately as the botrytis will quickly spread to neighbouring zinnia plants.

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Zinnias can be transplanted or direct-seeded in the garden in early spring. Seed germinates easily and plants grow quickly.

In nature, zinnias are typically 15 cm in height. However, through many years of breeding and hybridization, hundreds of different zinnias are available that range from 10-cm to one-metre tall. Flowers can be found in purple, red, pink, orange, yellow, cream, white and every shade in between. ‘Queeny Lime Orange’ is a 2018 All-American Selection winner that starts out as lime green and matures to light orange later in the season.

Zinnias are one of the best flowers for attracting pollinators and butterflies. Interplant your vegetable garden with a row of zinnias for better fruit production in your cucumber, melon and squash patch.

Generally, the taller cultivars with the flat-topped flowers are more adapted to pollinators and butterflies than the dwarf cultivars. The yellow-centred flowers with the disc floret provide more nectar than the double-flowering blooms.

Zinnias bloom throughout the season. Deadheading (removing dead flowers) not only encourages more flowers but also promotes branching of the plants.

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Fertilizing the plants with a 20-20-20 soluble fertilizer once per month will stimulate healthier plants and ample blooms. If transplanting zinnias in spring, water them with a 10-52-10 soluble fertilizer. Always mix any fertilizer according to label directions.

There are many different types of zinnias available. The Profusion series of zinnias are mounding plants, approximately 45-cm tall and up to 60-cm wide with profuse blooms (5-cm diameter). Many colours are available.

The Double Zahara™ series of zinnias are compact plants with excellent disease resistance — recommended for containers and flower beds. The fully double flowers are 2-5 cm. Deadheading flowers is not necessary in this series.

Two zinnias recommended as cut flowers are the Benary and Oklahoma series. Benary’s zinnia series produce giant flowers (10-15 cm across) in bold colours. The Association of Specialty Cut Flowers recommends the Benary series for its vigour, uniformity and productivity throughout the season.

The Oklahoma zinnia series produces medium-sized, semi-double blooms and displays good powdery mildew disease resistance. Deadheading is recommended for these cut flowers to increase branching and blooms.

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Cactus flowered zinnias are eye-catching and unique. These large blossoms (15-30 cm) grow on stalks up to 1.2-metres tall. The ray florets are multi-layered and quilled (individually rolled in a tubular shape). Recommended for cut flowers, the plants will produce several cuttings as a “come and cut again” flower.

If you’re looking for an easy annual flower with a lot of colour throughout the season, zinnias are the way to go. You could grow a new one every year and not get through all the colours and series in one lifetime.

My favourite is ‘Zowie!™ Yellow Flame’ but there are hundreds from which to choose.

This column is provided courtesy of the Saskatchewan Perennial Society, which can be contacted by email at saskperennial@hotmail.com. Check our website (www.saskperennial.ca) or Facebook page (www.facebook.com/saskperennial) for a list of upcoming gardening events.

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