I just LOVE Zinnias! They are so bright, happy and colourful and always brighten up the day. I do not know of any flower with more zing than a zinnia!!! They are such easy plants to cultivate, growing quickly and blooming heavily and providing long-lasting colour in the Summer flower bed, as well as attracting bees, birds and butterflies. The Zinnia genus (Photo 1 below) belong to the sunflower tribe (Heliantheae) (Photo 2 below) and the daisy family (Asteraceae) (photo 3 below) and and comprises of 22 species of annuals, perennials and small shrubs, though the species, with which we are most familiar, Zinnia elegans, is an annual. Since selective breeding began in the 19th century, there are now over 100 cultivars and an increasing number of interspecific hybrids. They were named after the German botanist Johann Gottfried Zinn (1727 – 1759).
Distribution and Habitat:
Zinnias are native prairie plants, which grow in the scrub and dry grasslands from the South-West United States (the majority of species) to Argentina, South America ( a few species), with the centre of diversity being Mexico, so they love hot temperatures, full sun and long hot Summers and are very drought-tolerant.Description:
Zinnias come in a huge range of shapes, sizes and colours, so there is a zinnia to suit every situation! Even within the one plant, the shape of its blooms vary widely. The classic zinnia has a long sturdy single erect stem, 10 t0 100 cm tall, with soft downy opposite stalkless linear to ovate pale to mid green leaves and topped by a single flower. Zinnia elegans has tall forms and dwarf varieties like the knee-high Magellan series (35 cm or 14 inches tall) and the tiny Thumbelina series (15-20 cm or 6 to 8 inches), while Zinnia angustifolia, especially the Crystal series is a creeping ground cover and is extremely drought-tolerant. The Profusion series is a cross between Z. elegans and Z. angustifolia and has good disease-resistance.Flowers range from the simple single daisy-like form with an open centre and conspicuous disc and ray florets to semi-double and double forms (most modern varieties), the disc florets of the latter being much less obvious or absent. The ‘true’ flowers, which produce the nectar are the tiny yellow florets. They have many different forms, described as : Cactus/ quill-like (long narrow petals); dahlia type; pompom spheres or buttons and domes; stars; and spiders. I love the form of the buds and the emerging quills!They come in every colour, except for blue, and I have even seen two different coloured flowers on the one plant. As they age, the colours change and deepen.Here in Australia, they bloom for a long time from Summer (end of January) through to Autumn (April/May).
Cultivation and propagation:
Zinnias are such easy tough plants to grow! I sowed the seed of Lambley’s Dahlia Flowered Mix in late 2015, the first year of my cutting garden, resulting in masses of flowers! They self-seeded with plants coming up in the nearby flower and vegetable beds in the Summer of 2016-2017 and I even had a few last season, though I think it is now time to sow fresh seed! Lambleys have a number of different hybrids. See: https://lambley.com.au/flower-seed-catalogue/z?items_per_page=25.
Zinnias are propagated from seed and should be sown directly into the garden, as their developing roots do not like disturbance, though having said that, I have transplanted zinnias once they have grown into sturdy young plants. They should be sown after the last frost and when the soil is warm. David Lambley often sows his seed in late November, early December, so I still have time to get some new seed sown! Sow seeds 1 cm deep and 8 cm apart, thinning to 30 cm apart when the first true leaves have formed, so there is plenty of air flow and powdery mildew doesn’t develop. A 60 cm tall plant will need a space of 45 cm between plants.They can also be started indoors 4 to 6 weeks before the last frost and sown in peat pots, which can be planted straight into the garden.Sow in fertile humus-rich well-drained soil in full sun and keep the soil moist, but not soggy, for young plants. Once they are established, only water as required (once a week if that!) and always water the base of the plant (never overhead) in the early morning, so the foliage and flowers have time to dry off before the evening.
Avoid cold draughts and wind, especially for the taller varieties. Otherwise, being prairie plants, they are tough, withstanding drought and tolerant of poor soils, including hard clay. They will shade out the weeds and do not require mulch.Seed usually germinates in 7 to 10 days and it takes 60 to 70 days (seed to flower) for the plants to bloom. Deadhead regularly to extend the flowering season. Pinching back the plants will result in a bushier plant and constant trimming encourages further blooms.
Powdery mildew: Plant disease-resistant varieties like Zahara zinnias or the Profusion series; never water overhead; ensure plenty of air circulation and avoid overcrowding; camouflage tall, disease-affected stems with a foreground of other plants; and finally, live with it! It only affects the leaves and stems, not the wonderful flowers, though of course, disease-affected plants can be removed if too unsightly!Leaf spot and leaf blight: also caused by fungi. To prevent, remove the debris from the base of the plant and keep the stems clean. Long wet Summers can be a problem!Save the seed by removing the old dried spent blooms and harvesting the small arrow-head shaped seeds. Store seed in a cool dark dry place, then sow directly in the following late Spring.Uses:
Because of their huge variety in shape, colour and size; their fast propagation, ease of growth and low maintenance; their drought-tolerance and toughness; and their long-lasting colourful displays all Summer, zinnias are a very popular garden flower, especially in cottage gardens and cutting gardens.There is a zinnia for every situation. The tall forms of Z. elegans look great at the back of the border, while the dwarf forms look wonderful along paths. Z. angustifolia, especially the Crystal series, is often grown at the front of borders, in raised beds or containers and as a ground cover. They can even grow in weightless environments like the International Space Station!They also make excellent companion plants for tomatoes, capsicums and beans- they self-seeded to the tomato patch and next to the beans last year! They attract bees for pollination and birds, especially hummingbirds, which eliminate white fly, and are a butterfly magnet par excellence! The latter prefer the flat single varieties rather than the double forms.Floristry
With their long vase life (5 to 7 days), huge range in colour and form and sturdy tall stems, zinnias are also popular in the cut flower trade. Their stems should be harvested at an angle above the bud joint, the bottom 2 cm recut on a sharp angle and the leaves stripped off most of the stem. Use preservative in the vase and replenish the water daily. They are not ethylene sensitive. In the Language of Flowers, a bouquet of mixed zinnias mean ‘Thinking of absent friends’,
while yellow zinnias denote ‘daily remembrance’; white zinnias ‘pure goodness’; magenta zinnias ‘lasting affection’; and red zinnias ‘steadfastness and familial ties’. Obviously, I was thinking about absent friends in April when making my colourful zinnia cushion!