How to grow zinnia flowers
It used to be that most of us grew zinnias in rows. You still can, but why not toss a few seeds around in your border, like the gardener did in the photo above? Since zinnias are so easy to grow from seed, that's a colorful, and economical, way to fill out a flower bed. Butterflies like the vivid, easy-to-spot colors and will be drawn to your garden. Plus, just imagine how many bouquets you could pick from this border!
Get your zinnias off to a good start, whether you plant seed or starter plants, by giving them the right growing conditions with these growing tips.
Choose the right spot
Choose a location with good air circulation and full sun — zinnias will be floppy and sickly in shade. And while these annuals tolerate a wide range of soil types, they’ll bloom best in a moist, well-drained soil that has lots of compost worked into it.
Plant when it is warm
Sow the seeds directly on tilled soil and lightly cover them, or set out seedlings you buy in cell packs when the soil is thoroughly warm (about the same time you’d put out tomato plants). Zinnias will languish in cold weather — they really do like the heat.
Dry conditions translate to healthier zinnias. If you have to water, apply it only at the base of the plant or use a soaker hose so the foliage stays dry — keep moisture off their leaves to prevent powdery mildew from developing. Add a couple of inches of organic mulch, such as compost, around the plants to keep the soil moist and you won’t have to do as much watering.
In good soil there’s really no need for extra fertilizer, but if you want, a light sprinkling of a low-nitrogen, slow-release food will keep them blooming all summer.
How to care for zinnia flowers
Zinnias are easy to grow. But like most plants, an extra bit of care will yield more, and healthier, flowers.
Growing straight stems
Most of the short zinnia cultivars do fine on their own, but tall, traditional types can be top heavy. A “corset” of stakes and twine is ideal. Put it in place while the seedlings are only a few inches tall, as in the illustration above. Zinnia foliage is raspy and rough, so even if you don’t weave twine across the circle, the plants will grasp each other and help hold up their neighbors.
One of the best things you can do to keep more flowers coming is to deadhead. But why wait for the flowers to fade or turn brown? Pick lots of bouquets, cutting just above a set of healthy leaves. In a week or two, you’ll find two new stems sprouting from that spot — and that means more flowers!
Grow zinnia flowers in a garden border
The photo above is a great example of how to use smaller and densely branched cultivars. They’re perfect for landscaping because they don’t need staking or even deadheading to look stunning. Plus, zinnias can take the heat, especially along a south-facing sidewalk like this one.
Add zinnias to containers
Zinnias make excellent container plants, growing best in full sun and tolerating the sometimes dry conditions that can happen if you forget to water on a hot day. Go ahead and crowd zinnias in containers. With old cultivars, this would have meant a bad case of powdery mildew on the foliage. But newer hybrids are extremely resistant to foliage disease. And their compact form means they’re easy to take care of, too. You don’t have to worry about pinching to keep their size in bounds. If some of the flowers start to look tired, snip them off and you’re done — except for watering, of course.
Add zinnias to a pollinator garden
Check out 12- to 14-inch-tall ‘Magellan Coral’ in the photo above. This large flower is the perfect landing pad for butterflies, who find abundant nectar in the tiny yellow florets in the center of the petals. Zinnias with more defined, easier-to-access clusters of the center yellow florets are better pollinator magnets, but you still get lots of bright color with the Magellan series and that will draw in the winged visitors to neighboring flowers.
Great for bouquets
Zinnias make fantastic cut flowers — plant a mass of multi-colored zinnias so you'll have plenty to cut for bouquets. Cutting the blooms will encourage more buds to form, so you'll keep getting more. Harvest a zinnia flower when it can pass a "wiggle test": grab the stem several inches below the flower head and shake it. If the stem is stiff and the flower doesn't droop or bend, it is ready to cut.
Find a zinnia for your garden
You're sure to find a zinnia to suit your needs with all the different sizes and forms available. They come in almost any color except blue (often with stripes, splashes or gradations of contrasting colors), with several flower shapes: single, double, button, and cactus-flowered. Let's take a look at a few great zinnia varieties you might like to try!