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How to grow the best zinnias

How to grow Zinnias in Australia #aboutthegardenmagazine.indd
Zinnias just love the warm sunny days of summer. You can grow them from seed from spring onwards. They require a full sun position to grow their beautiful big blooms. Most zinnias have soft, furry, light green leaves that vary in width depending on the species and are available in most colours of the rainbow. To promote more flowering keep cutting the blooms and you will have flowers all summer long. 

How to buy

Although zinnias are sometimes sold in punnets, they are best bought as seeds and sown directly where they are to grow. Varieties include the dwarf Zinnia linearis, an excellent container type with bright orange flowers up to 80cm in height; and Z. elegans with blooms in magenta, lime green, cream, blood red, tangerine, yolk-yellow, scarlet and pink. Cultivars have been bred to produce zinnias with cactus-type flowers, pompom flowers and dahlia-like flowers, as well as doubles and star-shapes, in a huge range of colours and sizes. The taller varieties are susceptible to strong winds, so if this is a problem in your garden select smaller strains.

Where to plant

Zinnias adore hot spots, and demand a well-drained position in full sun to give their best displays. Sowing beds should be dug over to a spade’s depth and worked until they are crumbly and friable. Mix into garden beds 5IN1 Organic Fertiliser to give the soil all the nutrients to fantastic growth. Sweeten the soil with lime if it is more acid than pH 6.5 and dig it in well. Water the bed until the soil is damp to a spade’s depth and allow the soil to settle for a couple of days before sowing the seed.

How to plant Zinnias

Choose a still, sunny morning on which to sow the seeds because zinnias require warmth to germinate. The seeds are large enough to be relatively easy to handle and should be spaced approximately 25cm apart. Cover to the depth specified on the seed packet with a light soil/sand/vermiculite mix or use a preprepared seed raising mix. Water the seed bed well with a fine spray. Zinnias are some of the longest-lasting annual plants in the flower garden, so as the seedlings emerge (approximately 10 days later) sprinkle a very light layer of mulch between the plants to help them survive extreme weather during their extended season.

How to maintain Zinnias

Once the seeds germinate keep them weed free and moist. When half-grown, pinch out the leaders to induce side shoots and growth points for lots more flowers. A fortnightly feed with a liquid fertiliser such as Searles Flourish® will keep the flowers blooming brightly and the foliage lush and green. Zinnias flower profusely from late spring until early winter if picked for an indoor display or deadheaded continually. Use the dead heads as a mulch around established plants.

Pests and diseases on Zinnias

Old zinnia plants are susceptible to fungal disease, although they will still bloom successfully if affected. Fungus grows best on damp foliage, so either water the plants with a dripper system or soaker hose, or if you’ve installed an overhead sprinkler system, water in the morning. Slugs and snails love young plants, so protect them with gritty mulch, beer traps, or a bait that is not toxic to pets and wildlife.

Gardening Products for growing zinnias in Australia home.indd

Bonus points

Zinnias are superb cutting flowers and last for up to two weeks in a vase. To prolong their life, add a teaspoon of bleach to the water and change it every other day. At the very end of the season, allow the seed heads to mature on the plant and save them for sowing the following spring.

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