I love growing zinnias. These colorful flowers are scattered throughout my garden each summer, and their bright colors and continuous blooms make everything seem more cheerful.
They’re ideal as cut flowers, can be used in your culinary creations, or planted in a children’s garden.
Zinnias are easy to care for and are quick growers that bloom early and then continuously throughout the summer and fall. Let’s talk about how to plant and care for these vibrant charmers.
All About Zinnias
Zinnias are members of the daisy family (Asteraceae). They produce a lush, multi-petaled, solitary flower on a tall, sturdy stalk. Most zinnias will continue to produce blooms each time the flower is cut, making them ideal as a cutting flower.
Zinnias produce flowers and seeds yearly, but they won’t reseed in your garden unless you live in USDA Growing Zones 9-11. In this warm climate, zinnias are a self-seeding annual that acts almost as a perennial.
If you live anywhere where winter temperatures drop below freezing, you must replant zinnias yearly. I like to use this opportunity to move them around every spring – making my bright zinnias pop up in new and exciting places each year.
These resilient, annual flowers are versatile and make a great addition to a butterfly garden, a cut flower garden, a kitchen garden, or a child’s play garden.
There are three types of zinnias, with a vast variety of cultivars in each class. Most of them belong to the species Zinnia elegans. Single, semi-double, and double-flowered zinnias are all variations of the number of rows of petals each flower has.
Single Flowered Zinnias
These zinnias have just one row of petals. You can easily see the center of the blossom. They’re very similar to a daisy in appearance.
Semi-Double Flowered Zinnias
Semi-double zinnias have a single row of petals, with extra petals stuck in at intervals. They look fluffier as flowers than the single-flowered zinnias, but you can still see the center of the blossom.
Double Flowered Zinnias
These are the fullest-looking zinnias. They have numerous, full rows of petals. The center of the flower is completely hidden. Despite the name, double-flowered zinnias usually have more than a double row of petals.
This type can also come in a variety of shapes – like the glorious “beehive” shaped zinnias and “cactus” zinnias.
Zinnias can come in a variety of heights as well as shapes. Tall, short, and mid-sized zinnias add depth to garden borders and visual interest to flower beds.
Notable Zinnia Varieties
No matter what type of zinnia you’re looking for, there’s a variety to suit you! From bright pinks and yellows to stunning terra cottas – zinnias come in a vast variety of colors. They grow as tiny dwarf plants and towering stalks. Here are just a few favorite varieties.
The tiny Dreamland series of dwarf zinnias are great as border flowers. They’re short plants, but their flowerheads are comparatively large, with fluffy, double heads that look stunning in any location.
Cut and Come Again
You can’t go wrong with the old, reliable Cut and Come Again series. Of course, all zinnias will continue to blossom if you cut their flowers, but I find this series is more eager to rebloom.
It produces more flowers, more consistently, and in a wide variety of colors than every other series.
The State Fair series includes some of the tallest zinnias on the market. These flowers grow to over 30 inches tall and produce huge, double flowers that tower over all the smaller plants in your garden. State Fair zinnias look fantastic against a wall or fence.
Growing zinnias from seed is easy. They germinate quickly and grow well in warm, frost-free soil. Start your zinnias after the last frost, when the soil is at least 50°F during the day. These are not frost-hardy plants.
Zinnias need at least six hours of sunlight a day to thrive. They do best in full-sun areas, but semi-sunny areas are acceptable as long as there’s enough consistent sunlight. In shadier areas, your zinnias may grow, but they’ll be sicky and stunted, with few blossoms.
Choose an area with plenty of air circulation as well. Zinnias can be prone to powdery mildew if they’re overcrowded.
Zinnias are adaptable when it comes to soil. But, poor soil will result in fewer blossoms. One year, my growing zinnias produced only a few small flowers, despite an ideal location. I tested the soil and discovered it was nutritionally exhausted!
For best results, plant your zinnias in rich, well-draining soil. Add plenty of compost or manure to the soil before planting. I like to add bone meal as well to boost phosphorus levels. The ideal soil for zinnias has a pH between 5.5 and 7.5.
Some of my best zinnias were grown in a sunny field, on a patch of ground that had been a chicken pen two years before and was replete with well-composted manure.
Depending on the variety of zinnia, you’ll want to give your plants between five and 20 inches of space between them. Over-spacing zinnias can give them a lonely, straggly look, while clustering them can lead to problems with mildew.
Once the soil is prepared, the reasonable danger of frost is past, and you’ve got an idea of spacing, go ahead and pop your zinnia seeds into the ground. Sow the seeds about a quarter inch deep in loose, well-composted soil. Then, water them well.
You don’t need to drown these seeds in water, but try to maintain consistently moist soil throughout germination. Young seedlings should also have consistent, light watering. We want to maintain a welcoming environment for the young plants, without encouraging disease.
Now to the best part of growing zinnias. Your plants will start producing flowers in about 60 – 70 days from seed. The time varies based on variety and environment. A warm, sunny, nutrient-dense location will speed things along. Cold weather and poor soil will delay flowering.
As they blossom, either cut the flowers for use in bouquets or deadhead consistent after each blossom dies. If you continue to cut and deadhead, your zinnias will continue to blossom until the fall frost kills them.
If it’s a particularly dry summer, water your zinnias about once a week to maintain soil moisture. Check the soil if you’re not sure your flowers need water – you should feel some moisture about a half-inch under the soil’s surface. If everything feels dry to the touch, add some water.
When growing zinnias, avoid wetting the leaves. Water the soil, not the plant. This will help prevent mildew and keep your flowers healthy.
If your plants start getting leggy, pinch them back to encourage them to bush out a bit. Cutting flowers for tall vases is a great way to remove stems that are becoming unmanageable tall.
Pests and Diseases
You’ve probably guessed that powdery mildew is the number one health risk you’ll encounter when growing zinnias. Prevention is the best cure for mildew, so keep those plants well-spaced and moderately watered.
If you see signs of powdery mildew, clean up any weeds and use a mild anti-fungal treatment like Bonide’s copper fungicide.
You can make an effective remedy by adding a tablespoon of baking soda, to a tablespoon of non-detergent liquid soap, and a tablespoon of salad oil. Mix into a gallon of water. Shake the whole solution well and spray it onto plants with powdery mildew.
Occasionally, grasshoppers can also damage your zinnias. If you see grasshoppers in the garden, add a bit of neem oil to your insecticidal soap. The soap won’t affect the grasshoppers, but the neem oil will.
You can stop two threats at once by combining treatments.
Are Zinnias Edible?
Zinnias are safe to eat, believe it or not. Who knew growing zinnias could be so multi-purpose?
The whole plant is safe, but only petals are generally eaten. This is because zinnias are a pretty bitter-tasting plant. Bitter foods don’t play a significant role in our modern diet, but they’re extremely good for us.
Bitter foods wake up the digestive system. They help us digest food better and absorb more nutrients from our meals. Bitter foods also support the liver and kidneys. So, include some zinnia petals in your next salad.
For the best flavor, pull the petals off the seed head and scatter them in a salad of spicy arugula, bitter dandelion greens, and sweet buttercrisp lettuce. Add some sweet violets as a balancing flower, and eat the salad at the beginning of your meal.
Starting a meal with something bitter is the best way to ensure healthy digestion. Bitter salads are only one option. I like to pop a small zinnia flower into a “garden party” gin and tonic.
With some rosemary, thyme, yarrow flower, and whatever else is in season – zinnia flowers look and taste perfect. Top it off with a slice of lime, and you’ve got an ideal pre-dinner cocktail for late summer.