A simple guide on how to grow Zinnia Flowers. Zinnias are one of the easiest annuals to grow; they make beautiful cut flowers and bloom prolifically. These show-stopping flowering plants are low maintenance, and effortless to grow from seed.
They are available in a vast range of single or double blooms, dwarf sizes, tall varieties, and different colors. This guide will step you through the process of how to grow Zinnia flowers from seed.
Table of contents
- How to Grow Zinnia Flowers
- Why You Will Love Growing Zinnias
- Types of Zinnias
- Varieties of Zinnias That I Grow
- When to Plant Zinnia Flower Seeds
- Where to Plant Zinnia Seeds
- How to Plant Zinnia Seeds
- How to Deadhead Zinnias
- Garden Essential for Growing Zinnias
- Zinnia Diseases
- When to Harvest Zinnias Flowers
- Frequently Asked Questions on How to Grow Zinnia Flowers
- Other Popular Varieties of Zinnias
- More Flower Gardening Posts You May Enjoy
How to Grow Zinnia Flowers
Zinnia flowers can create vibrant colors in the garden, putting on a dazzling display all summer long. While I love the bright color of Zinnia flowers, I have chosen to grow all white Zinnia varieties for the past several years.
In this post, I hope that you will learn just how to grow Zinnia flowers for your own cut flower gardens. One of the easiest cut flowers to grow, you will enjoy blooms and fresh bouquets all summer long.
Why You Will Love Growing Zinnias
- Easiest Cut Flowers to Grow: growing Zinnias is the perfect first cut flower for beginning growers. Quick to germinate, these annual flowers can go from seed to bloom in less than eight weeks. They are low-maintenance, grow quickly, and bloom heavily.
- Attracts Pollinators: a great reason to plant Zinnias in the garden is that they attract beneficial garden pollinators such as butterflies and bees. In fact, Zinnias are a preferred nectar plant of Monarch butterflies.
- Easy to Save Seeds: the seeds are easy to save from mature zinnias. Once the flowers dry on the seems, the seeds can be removed and stored for the next season.
- Long Growing Season: zinnias planted in late spring after the last frost will bloom from early summer to late fall.
Types of Zinnias
Zinnia elegans is the most popular zinnia species. Native to Mexico, this annual is widely grown around the world. Zinnia elegans is the most popular variety and the easiest to find in the garden center or start from seed. This variety is the best for great cut flowers as they have long, strong stems.
Zinnia augustifolia is a short variety of Zinnia only growing to about 18″ tall. The flowers are small and are best enjoyed in hanging baskets or used in the front of the border in a flower garden. While this variety is tolerant of heat and drought, they are not suitable for cutting garden flowers.
Varieties of Zinnias That I Grow
Benarys Giant White
- Benary’s Giant White – Vigorous, healthy plants with long, strong stems that have 4-6″, fully double blooms, with a dahlia-like flower. One of the tall plant varieties, the Benary’s Giant White can grow up to 40–50″ and they have an excellent long vase life. This variety holds up well in summer heat and rain and has a low susceptibility to powdery mildew.
- Oklahoma White – Prolific, 1 1/2-2 1/2″ semidouble petite, and double blooms, with strong sturdy stems. Blooms are pure white with a green-tinted center. Excellent, reliable accent flowers for cut flower arrangements, these cut-and-come-again flowers will yield multiple cuts over the season.
When to Plant Zinnia Flower Seeds
Zinnias are cold weather-sensitive and should be planted after all danger of frost has passed. They are easy to grow and do best when directly seeded into the garden.
Zinnias can be started indoors 4-6 weeks before your last frost date. If growing indoors and then transplanting, do so carefully when the plants are young. It is essential to try not to disrupt the roots when removing the plants.
It is best to use peat pots or another type of biodegradable for starting Zinnias indoors. Once it is time to transplant, the entire container can be placed in the ground without damaging the roots.
To find out the frost date in your area, look up your first frost date and last frost date by zip code. It is also good to know what USDA Hardiness Zone you live in. It helps you as a gardener determine which plants are most likely to thrive in your location.
Where to Plant Zinnia Seeds
Zinnias like the heat and sunshine, so it is essential to plant them to grow in full sun for at least 6 hours a day.
Zinnias can adapt to most garden soil conditions, but ideally, the perfect soil would have a pH between 6.3-6.8 preferred, be well-draining, and rich in organic matter.
How to Plant Zinnia Seeds
Direct sow seeds 1/4″ deep in a row, and cover them with soil and water. The soil moisture should be kept damp until the zinnia seedlings begin to germinate. In 3-5 days at 80-85°F, you will see germination.
Once your seedlings are 4 inches high, they will need to be thinned out if they are growing too close together. Refer to the back of the seed packet for specific advice regarding the variety you are growing. Generally, plants should be spaced 9″-12″ apart.
To thin out seedlings, the best way is to gently pluck the young plants out of the ground by pulling at the base of the plant.
How to Deadhead Zinnias
To keep your zinnias blooming, one of the most important steps in learning how to grow Zinnia, is to deadhead the blooms. Deadheading Zinnias prolongs the plants blooming time, encouraging the flowers to continue to bloom.
Once the blooms begin to fade, cutting back the Zinnia flower heads will promote new growth. Zinnias are incredibly resilient, and deadheading will not harm the plant in any way.
To deadhead Zinnias, determine how far back you want to cut the stem. Then, using a pair of sharp garden scissors cut just above a set of leaves. This will encourage the plant to grow new stems and blooms where you have cut.
Garden Essential for Growing Zinnias
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- Garden Scissors
- Neem Oil – helps to prevent powdery mildew and some garden pests.
- Seeds – I have personally ordered from Johnnys Seeds and Floret Farmer and have had great success with both companies.
Zinnias can be susceptible to fungal diseases and particular pests. The best way to prevent diseases is to take preventive measures.
How to Prevent Powdery Mildew
- Space plants at the recommended distance on the back of the seed package to allow for good air circulation.
- When watering Zinnias, use a soaker hose or avoid getting the foliage wet. Most fungal diseases, such as powdery mildew, come from damp conditions and locations that do not drain well.
- Plant Zinnias in a sunny spot.
- Use Neem Oil to help prevent powdery mildew. If small white spots begin forming on leaves, using Neem Oil helps to kill the powdery mildew spores on the leaves.
Dealing with Zinnia Pests
Aphids: damaging leaves as they feed on the plant’s sap; aphids are an enemy in the garden. To help control aphids, spray a natural solution like a soap-water mixture, Neem oil, or essential oils.
Japanese Beetles: appearing in mid-summer, the best way to deal with Japanese Beetles is to pick them off by hand and drop them in soapy water.
Worms: feeding on both leaves and flower buds, any worm can be a severe problem. The best way to deal with this pest is to go out in the early morning or late evening to find them. Pull them off the plants and either squish them or drop them in a bucket of water.
When to Harvest Zinnias Flowers
Harvesting Zinnias at the right stage is essential. This helps to ensure that you get long-lasting blooms for your bouquets.
Harvest blooms when you can hold the stem 8 inches below the bloom, shake the stem, and the blooms stay stiff and upright. If you shake the stem and the flower bends easily, it is not quite ready to harvest.
Cut just above a leaf node or bud to encourage new blooms on the remaining stem when cutting stems. Cut long stems, remove the foliage, and put it into the water right away. Zinnias can last in a vase for 5-7 days.
Frequently Asked Questions on How to Grow Zinnia Flowers
Do Zinnias Come Back Every Year?
Zinnias are annuals and do not come back every year. However, it is effortless to save the seeds and have plenty to plant the following year.
Where is the Best Place to Plant Zinnias?
Whether Zinnias are grown directly in the ground, in pots, or in raised garden beds, the best place to plant them is in well-drained soil high in organic matter.
Do Zinnias Need Sun or Shade?
Zinnias grow and flower best in full sun—plant zinnias in an area that will get at least 6 hours of sun each day.
Should You Pinch Zinnia Plants?
The secret to growing the best zinnias with the longest stems is to pinch the young plants. When plants are 8″-12″ tall, use sharp garden pruners to snip off the top of the plant, just above a set of leaves.
Should You Deadhead Zinnias?
Zinnias should be deadheaded. Either cut mature stems to use in fresh bouquets for the home or remove the old blooms after they have faded. Deadheading and regular harvesting are essential to prolong blooming and promote branching.
How Long Do Zinnias Bloom?
Zinnias are a well-loved cut flower for the garden because of their long bloom time. Zinnia flowers bloom from late spring until the first frost in the fall.
Other Popular Varieties of Zinnias
- Zinnia Benary’s Giant Salmon Rose – featuring beautiful colors in a warm peachy tone these plants have a high percentage of double flowers. Plants reach 3-4 feet tall and have long, strong stems making them an excellent choice for growing along the back of the border in a flower garden.
- Zinnia Golden Hour – A beautiful collection of warm buff, honey, and soft apricot blooms that Floret Farmer discovered in their fields. This is one of the taller varieties growing to a height of 36″-48″.
- Zinnia Oklahoma Ivory – Versatile creamy ivory color and pretty double blooms. These reliable plants produce large quantities of medium-sized flower heads that have long, strong stems and thrive in the heat. This variety grows to a height of 30-40”.
More Flower Gardening Posts You May Enjoy
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- Garden Shed Decorating Ideas
- Galvanized Washtub Planters
- How to Plant Dahlia Tubers
- How to Split Hostas
With this easy guide on how to grow Zinnia flowers, my hope is that you will plan to add them to your cut flower garden. For more planting guides be sure to check out one of my other favorite cut flowers, Dahlias!
This post was updated with photos and text on August 17, 2021