Zinnias: Growing Guide

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, effortless to grow from seed. They are available in a vast range of single or double blooms, dwarf sizes, tall varieties, and different colors.

The Ultimate Guide to Zinnias
Growing Zinnias

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.

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.
How to Plant Zinnias

Types of Zinnias

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.

Monarch on Zinnia

Varieties of Zinnias That I Grow

  • Benary’s Giant White – Vigourous, 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.
How to Care for Zinnias

When to Plant Zinnias

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.

White Zinnias

Where to Plant Zinnias

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, 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.

Zinnia Elegans

How to Deadhead Zinnias

To keep your zinnias blooming, you have to keep cutting them. 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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Benarys Giant White

Zinnia Diseases

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.
Zinnias Pests Diseases

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.

Growing Zinnias

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.

Zinnias in the Garden

Frequently asked Questions

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 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 to Grow 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”.
Oklahoma White Zinnia

More Flower Gardening Posts You May Enjoy

  • Rustic Garden Ideas and Design for Backyard: Suppose you desire a rustic garden filled with inspiration, ideas, and decor with a lived-in feel. In that case, a great way is to add some vintage garden decoration from flea markets, auctions, and garage sales to give it a casual country landscape design.
  • Garden Shed Decorating Ideas: Charming country garden shed decorating ideas that are simple in design with a decorated front porch. Known by various names, rustic she sheds and potting sheds, this space is used for outdoor tool storage and potting up cottage garden plants in a quaint place.
  • Galvanized Washtub Planters: Use galvanized washtub planter ideas in the landscape to create a dazzling flowering display. Creating a unique container gardening idea, old vintage wash tubs can be loaded with annuals or perennials, forming a brilliant season-long vivid arrangement. Placed on the front porch or in the yard, galvanized tub planters are beautiful in any location.

This post was updated with photos and text on August 17, 2021

Thank you for sharing!

23 thoughts on “Zinnias: Growing Guide”

  1. This was great. I planted zinnias for the first time this year. They are beginning to flower (although mine look smaller than yours) and I was just wondering what I do now. I didn’t know about cutting the inner top flower off to encourage more outer growth. Doing this today! Hope I didn’t wait to long as they are a little taller than 18". Fingers crossed.

  2. Thanks so much for sharing these tips. You may already be planning this, but I would love it if you could do a post sometime about how to harvest and store seeds from the blooms for the next season. I love everything you do and your photography is amazing!!!❤️

        • There are several youtube posts about how to harvest and store zinnia seeds. I did it last year and have started several varieties inside this year.

    • Last fall, i got a faded zinnia flower from my friend’s plant. It had gotten far into being all seeds– brown and dry. This spring I sprinkled the individual seeds on some bare soil and by surprise and delight they germinated! They are tall now and seem to be about to bloom.

      • Zinnias are amazing! They grow so well from seed and have never failed me. I always tell people they are the perfect cut flowers for beginners.

  3. Dear Sarah,
    Your posts are always so encouraging to me. Thank you for sharing your lovely home with us. I love simple living too. Just wanted to say you are appreciated.

  4. I am a first time grower, varieties of Zinnia. My Zinnia’s are great, full bloom, and gorgeous. Although I got worried about having them turn colors on my leaves. I read your article and this help me understand more about Zinnia’s. Thank you for sharing your tips.

  5. I save zinnia seeds every year. I simply dry the dead flower heads (on a screen or colander) until completely dry and then store them in plastic jars (Talenti gelato is my favorite), It is crucial to dry them so they don’t get moldy.
    Next year I simply toss them in a circular area and rake the soil around them and keep them moist. The result is a profusion of cut-and-come-again flowers all season long.

    PS I am also planting seeds throughout the season, including mid-August, which I have read produces blooms all through the fall. My experience is that they bloom all through the fall when you cut them back. Great bouquets! And I love on ZInnia Street!!


  6. I read that pruning the zinnia will provide more bloom . I am going to try this and see what results I see. I enjoyed your article. Thank you for sharing

  7. Hello I am looking for advice. I plan to plant 1 acre of zinnias and have some questions.
    I plan to use a herbicide to kill the grass in the 1 ac area. then ,with a tractor, plant the seeds via a no-till method . Is this correct? or is there a better way to plant 1 acre?

  8. Hello,
    This is my second year planting Zinnias and I will admit bc of how easy last year went, I was very laxed and basically just shook my seeds all over the areas i was planting using a mix of different zinnias, covered with some soil and proceeded to water. This was about 3 weeks ago and boy do I have plenty of growth coming up. The only issue I see is that some of the areas are very tightly clustered together. Do I just call it a loss and thin out these clusters, or am I able to try to use a soil knife to pull out a patch and replant in other areas?
    I also did the same in other areas of my garden with Wild Flower mix in hopes of a meadow type look, and those are in tight clusters as well. I am hoping I did not mess up my garden ( i like to grow from seeds) this late in the season. Any advice? Thanks for a great article.

    • I would suggest that you thin them out so that they are not in clusters. Sorry, I didn’t see your message much sooner. You could try moving the ones that you pull to another space, but I don’t know how well that will work. I have had some success doing this and then other times, the plants don’t make it.

  9. I love Zinnias and have a lovely bed this year. My question is about leaving the flowers long enough for the pollinators to make maximum use of the blooms. (I’m happy to enjoy them in the garden and not bring many inside.) But I also want to deadhead before it’s too late. Does that make sense? What is your advice?

    • My suggestion would be to leave them until they start to fade and look bad if that makes sense. It will be noticeable when they begin to fade and at that time, I would deadhead them.

  10. I notice on some of the random leaves of my zinnias there are small holes……is this worm related? Or just how they sometimes grow? They are still quite healthy so just wondering. Love your posts!

    • That is the work of the little worm that I showed in one of the photos. It seems as though I pick them off and more just keep coming back. They have been really bad this year.


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