How to grow zinnias
For anyone just getting started on their gardening or cut flower journey, there is perhaps no easier place to start than with zinnias.
Zinnias are no longer the subject of ridicule. Where once these flowers were considered a bit daggy and very old fashioned (but not in a cool vintage way), they are now right on trend and come in a huge range of colours and shapes. Legend has it that Martha Stewart made them cool again. Go figure.
Zinnias are an annual, which means they grow and flower in the same season. They are best planted once the soil has really warmed up, and we plant ours mid-November and then again mid-December and again mid-January. If you are anywhere in the Southern Hemisphere and enjoy long warm summers and autumns, it’s not too late to plant these right now.
Although they are able to be direct planted into the garden, I like to start everything in paper pots. This helps me remember where my seedlings are as well as control pests like slugs. Zinnia do not like to have their roots disturbed when being transplanted. If you are going to plant them into seedling pots first, it is best to use a pot that can be planted straight into the ground (like jiffy paper pots) rather than using plastic seedling trays requiring you to remove the seedling for planting (and hence potentially disturbing the roots).
Either direct seed or plant them out about 20cm apart. If you are direct seeding, plant two seeds in each spot and thin back to strongest seedling after germination. Plants can get big and flop out onto the path, so while you’re at it hammer in some tomato stakes about every 50cm around the bed and run some twine right. This will corral the plants and stop them falling over.
Zinnias grow really quickly, and you can expect to be harvesting within as little as six weeks after planting out (8 for direct seed). Zinnias do best if they have consistent watering (but don’t need excessive amounts) and a liquid feed (worm wee, fish emulsion, etc) once a week.
If you want cut flowers, don’t select any ‘dwarf’ seeds. There are terrific seed options available here in Australia from Lambley Nursery (www.lambley.com.au/flower-seed-catalogue/) and The Seed Collection (www.theseedcollection.com.au). One of my favourite zinnias is Envy Lime from The Climbing Fig (www.theclimbingfig.com.au) - just love that zingy lime colour. It looks great with dusty pinks, blues, just about everything. Further afield Floret (www.shop.floretflowers.com) have an incredible choice - I’m loving Zinderella Peach. Beware that ‘doubles’ may not actually bloom double when temperatures are very high - still very lovely, but just not what you might have been expecting.
For long stems, make sure to pinch out the first center stem that appears as the plants grow. Once the Zinnia plant reaches about 10-15 cm, pinch it back - be ruthless, I take mine down to just above the first set of branching leaves right near the bottom of the plant. This will cause the plant to throw out more branches, giving you more blooms. And the more you pick, the more you get. These babies will grow right through until winter frosts kick in.
