Mastering Zinnias: Tips for Growing, Harvesting, and Designing
Zinnias are the unsung heroes of summer fields, bursting with color and life when the heat feels unbearable. They’re the kind of flower that embodies resilience, producing bloom after bloom no matter how relentless the season gets. Whether you’re growing for market bouquets, weddings, or just the joy of having a garden alive with color, zinnias have something for everyone.
These blooms are a grower’s dream: easy to care for, endlessly productive, and beloved by customers. There’s a reason they’re one of our Top 5 Field Favorites, and I can’t wait to share why zinnias deserve a prime spot in your growing plans.
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A golden-hour glow over the zinnia patch, showcasing the stunning Benary Salmon-Rose and Persian Carpet varieties.
Why Zinnias Are a Must-Grow for Flower Farmers
Zinnias are one of those crops that just keep giving, which is why they’re a top pick for flower farmers—especially those working on a smaller scale. Vibrant, versatile, and endlessly productive, zinnias earn their keep in the field season after season.
For small-scale growers, zinnias are a reliable workhorse that thrives even in challenging conditions. With minimal inputs and consistent care, these blooms produce buckets of stems all season long. Whether you’re drawn to the intricate beauty of smaller varieties like Persian Carpet or want the bold, statement-making blooms of Benary’s Giant, there’s a zinnia to fit every style and purpose.
What makes zinnias a standout crop?
Productivity: Zinnias continuously produce with regular harvesting, making them a cost-effective and reliable choice.
Heat Tolerance: They shine in the heat of summer, blooming when many other flowers struggle.
Pollinator Magnet: Their open blooms attract butterflies, bees, and other beneficial insects, adding an eco-friendly touch to your field.
Versatility: From cheerful market bouquets to elegant wedding arrangements, zinnias fit into virtually any design style.
Customer Favorite: Their vibrant colors and nostalgic charm make them irresistible to market customers and event clients alike.
Looking to make every inch of your flower farm work harder for you? Check out our blog, Maximizing Production for the Small-Scale Flower Farmer, for practical tips to boost your blooms.
A Unicorn Mix zinnia adds a playful ombre touch to the field with its unique gradient hues.
Color and Texture Diversity
Zinnias offer an incredible range of colors, from bold reds, oranges, and purples to soft pastels like apricot, blush, and cream. Their textures are just as diverse, with options like ruffled petals, compact blooms, and large, dahlia-like forms. These qualities make zinnias a versatile choice for both casual bouquets and elevated event work.
In recent years, small-scale breeders have introduced exciting new forms and colors that elevate zinnias beyond what we’re accustomed to seeing in garden centers. These varieties—designed with weddings and high-end florals in mind—feature muted tones, intricate petal shapes, and unique bicolor patterns that appeal to modern design sensibilities.
Zinnias also hold a unique value in being best sourced locally. Their delicate petals and hollow stems don’t ship well, meaning they’re often unavailable through wholesale suppliers. This makes zinnias a premium crop for local growers, offering customers fresh, high-quality blooms they can’t get elsewhere.
Walking through a row of blooming zinnias feels like the heart of summer—alive, colorful, and brimming with possibilities. Whether you’re filling subscription bouquets or growing for events, zinnias bring unmatched value and beauty to your field.
Preparing the next generation of zinnias with Bootstrap Farmer’s durable air-prune trays in the propagation house.
Starting Zinnias from Seed: Fast and Flexible
Zinnias are one of the easiest flowers to grow from seed, making them perfect for both beginners and seasoned farmers. These fast-growing beauties germinate within a few days when given the right conditions, and their rapid growth means you’ll be planting them out in no time.
Seed Sowing Basics
When to Start: Start zinnia seeds indoors 4–5 weeks before your last expected frost date.
Ideal Substrate: We prefer using Pro-Mix HP, a high-porosity potting mix that ensures excellent drainage and airflow for healthy root development.
Seed Depth: Sow seeds about 1/4 inch deep, ensuring good contact with the soil. Lightly cover with substrate and mist to moisten.
Temperature: Zinnias germinate best in soil temperatures of 70–75°F. A heat mat can help maintain consistent warmth if needed.
Moisture: Keep the soil evenly moist but not waterlogged to avoid fungal issues.
The Right Trays for Zinnias
Zinnias grow fast and are sensitive to becoming rootbound, which can stunt their growth. For this reason, we recommend using Bootstrap Farmer’s 72-cell air-prune trays. These trays encourage strong root systems and provide enough room for zinnias to grow vigorously before planting out. If you’re working with larger seedlings or want to extend the indoor growing time, 50-cell trays are also a great option.
Hardening Off Seedlings
Zinnias are frost-sensitive, so hardening off is an essential step before transplanting. Gradually expose seedlings to outdoor conditions over 7–10 days by setting them outside for a few hours each day, increasing the time daily. This process strengthens seedlings and reduces transplant shock.
Tip: For more detailed transplanting advice, check out our Transplanting Seedlings Guide for step-by-step tips, including how to harden off your plants.
Propagation by Cuttings
Zinnias can also be propagated by cuttings, making it an efficient way to expand a stunning variety mid-season. Here’s how:
Select a Cutting: Choose a healthy, 4–6 inch stem from the parent plant.
Prepare the Cutting: Remove the lower leaves, leaving only a few at the top.
Rooting Method:
Place the cutting in water and wait for roots to develop.
Alternatively, plant it in a well-draining substrate, such as a mix of perlite and potting soil.
Monitor: Keep the substrate evenly moist and the cutting in a warm, bright location out of direct sunlight.
Pro Tip: Using a rooting hormone like Clonex can significantly increase success rates and reduce the time needed for root formation.
With proper care, roots will form in about 1–2 weeks, and your new zinnia plant will be ready for transplanting!
Timing to Transplant
Expect zinnia seedlings to be ready for transplanting 4–6 weeks after sowing. Look for healthy plants with strong stems and a few sets of true leaves. Avoid letting them stay in trays too long, as zinnias dislike being rootbound.
Direct Sowing Option
In warmer climates or for larger-scale plantings, zinnias can be direct sown once soil temperatures reach 60–65°F. Space seeds according to the intended plant spacing and keep the soil evenly moist until germination. This method works well for staggered succession planting throughout the summer.
Watch Out for Seedling Pests
Seedlings can be vulnerable to pests like earwigs, which are especially problematic in damp conditions. Trap earwigs using soy-oil traps—shallow containers filled with soy oil placed near the seedlings overnight. These traps effectively lure and capture earwigs, which can then be disposed of in the morning.
Succession Planting for Continuous Blooms
For continuous blooms all season, sow zinnia seeds every 3–4 weeks through mid-summer.. This ensures a steady supply of fresh flowers for markets, events, or CSA subscriptions.
Looking to perfect your seed-starting game? Check out our Seed Starting Guide for in-depth tips and tricks, our When to Plant: Frost Dates, Soil Temps, and Timing blog for detailed timing strategies, or our Advanced Guide to Succession Planting for strategies to keep your fields blooming all season long.
The delicate peach tones of Alpen Glow zinnias light up the patch with subtle elegance.
Planting Out Zinnias: Setting Up for Success
Once your zinnia seedlings are hardened off and ready to go, it’s time to get them in the ground. Zinnias thrive when given the right conditions, and a little prep goes a long way in ensuring a healthy, productive patch.
When to Plant Out
Plant zinnias outdoors when nighttime temperatures consistently stay above freezing (ideally above 40–45°F). This ensures young plants avoid frost damage and thrive in their new environment.
For earlier planting in cooler climates, consider using low tunnels to protect plants from unexpected dips in temperature.
Spacing Guidelines
Our Spacing: We plant zinnias at 7x7 inches in our arid climate. This closer spacing encourages sturdy stems, maximizes production, and provides natural shading to suppress weeds.
Industry Standard: Zinnias are commonly spaced 9–12 inches apart, particularly in more humid regions where improved airflow helps reduce disease pressure.
Pro Tip: Adjust your spacing based on your soil and climate. Tighter spacing works well in drier areas but may increase disease risk in more humid conditions.
Weed Management
Preparation: We use silage tarping ahead of planting to smother weeds and prepare the bed efficiently.
During the Growing Season: Zinnias perform exceptionally well in weed cloth, which helps regulate soil temperatures, retain moisture, and minimize weed competition.
Watering Needs
Zinnias prefer consistent moisture but don’t tolerate waterlogged soil.
In the heat of summer, their rapid growth makes them surprisingly thirsty. Drip irrigation is an excellent way to provide deep, even watering without wetting foliage, which can lead to disease.
Soil Health
Amend Ahead of Time: We like to amend the soil well before planting zinnias, incorporating a slow-release fertilizer that breaks down gradually over the season to provide consistent nutrients.
Test and Improve: Conduct a soil test to identify and address deficiencies. Zinnias thrive in well-drained, nutrient-rich soil with a slightly acidic to neutral pH (6.0–7.0). Amend soil as needed based on test results.
Building Soil Health: Over the years, we’ve worked to build up the health of our soil, now home to a thriving population of worms. These natural soil builders continuously enrich the soil throughout the growing season, improving structure, drainage, and fertility.
Homemade Compost: Instead of using bovine or horse manure, which can increase soil salinity, we opt for homemade compost made from garden waste. Our chickens work this compost, enriching it further and ensuring it’s fully broken down.
Fully Composted Indicators: Ready-to-use compost should be dark, crumbly, and have a pleasant, earthy smell. It should no longer have identifiable pieces of the original materials and should feel slightly moist but not wet.
Organic Matter: Adding organic matter like compost enhances soil structure, improves water retention, and boosts nutrient availability.
Drainage: Zinnias are sensitive to waterlogged soil, so ensure good drainage, especially in regions prone to heavy rains.
Cover Crops and Crop Rotation: In the offseason, planting cover crops or rotating zinnias with other crops helps replenish nutrients and reduces disease buildup in the soil.
Pest Monitoring at Planting
Young zinnia plants can be vulnerable to pests, with earwigs being a top challenge for us, especially targeting tender growth. These pests can quickly damage seedlings if not controlled.
Earwigs: Use soy oil traps or rolled-up newspaper to trap and remove them overnight.
Other Pests: Watch for aphids, which can stunt growth, and cutworms, which may sever seedlings at the base.
Regularly inspect your plants, especially during the early stages, and address issues promptly to ensure healthy establishment.
Low Tunnels for Season Extension
Zinnias benefit from low tunnels to protect them from unexpected frosts at both ends of the growing season.
Early Season: Use low tunnels to give zinnias a head start, especially in cooler climates where spring temperatures can fluctuate.
Late Season: Cover plants with low tunnels when frost threatens in the fall to extend your harvest into the cooler months.
Want to learn more about season extension methods? Check out our Season Extension Guide for tips on using low tunnels effectively!
Pinching Zinnias for Maximum Production
Pinching zinnias encourages branching, resulting in more stems and a longer harvest window. This simple technique can greatly increase your yield and the quality of your blooms.
When to Pinch: Once plants have 2–3 sets of true leaves, pinch the main stem just above a leaf node. Avoid pinching too early, as this can stress young plants, or too late, as it may delay flowering.
How to Pinch: Use clean scissors or your fingers to remove the main stem, ensuring the cut is just above a healthy leaf node.
Results: Pinched zinnias will produce multiple flowering stems, leading to a bushier plant and a longer harvest window.
When to Skip Pinching: If you're planting zinnias for a quick succession to meet a tight timeline, skipping pinching may result in earlier blooms, though with fewer stems.
Trellising for Sturdy Zinnias
Zinnias can grow tall and are prone to falling over in strong winds or heavy rain, which can damage stems and reduce harvest quality. Proper trellising is essential to keep plants upright and productive throughout the season.
Single-Layer Trellising: For shorter varieties or areas with less wind, a single layer of hortanova trellising placed at about 12–18 inches above the soil is usually sufficient.
Multi-Layer Trellising: Taller zinnia varieties or those grown in windy areas benefit from multiple layers of trellising. Add additional layers of netting every 12–18 inches as the plants grow to prevent bending or breaking.
Trellising Setup: Install trellising when plants are small to avoid damaging established stems. Use sturdy t-posts or wooden stakes to secure the netting, ensuring stability throughout the growing season.
DIY Tip: Incorporate trellising into low tunnel setups for early-season zinnias to provide extra protection from wind and frost.
Grow Tip: Ensure proper spacing between rows to allow airflow and reduce the risk of disease while still supporting upright growth.
Pro Tip: Using both hortanova trellising and weed cloth not only improves plant health but also reduces labor by cutting down on weeding and broken stems.
Rows of pastel zinnias from Floret Flower Farm showcase their vibrant range and versatility.
Managing Pests and Diseases
Zinnias are generally hardy and resilient, but like any crop, they can face challenges from pests and diseases. A proactive approach, combined with healthy cultural practices, is the best defense.
Diseases to Watch For:
Powdery Mildew:
Cause: Thrives in warm days and cool nights, particularly with poor airflow or overly crowded plantings. Overuse of high-nitrogen fertilizers or foliar sprays like fish emulsion can exacerbate the problem by promoting soft, lush growth that’s more susceptible.
Prevention:
Space plants adequately to ensure airflow.
Use trellising to keep foliage upright.
Water at the base of plants rather than overhead.
Apply home-brewed compost tea as a preventative measure to boost plant immunity naturally.
Treatment Options:
For early signs, remove affected foliage to reduce spore spread.
Organic sulfur-based fungicides can be effective when applied as a preventative or at the first signs of infection. Avoid applying sulfur during hot weather to prevent plant burn.
Neem oil or potassium bicarbonate sprays can also help manage outbreaks.
Rotate fungicides with different modes of action to avoid resistance build-up.
Aster Yellows:
Cause: Spread by leafhoppers.
Signs: Stunted plants, yellowing, and deformed flowers.
Prevention/Treatment: Use row covers during high leafhopper activity, deploy sticky traps, and remove infected plants promptly.
Alternaria Leaf Spot:
Cause: Fungal infection in wet, humid conditions.
Signs: Dark, circular spots with yellow halos on leaves.
Prevention/Treatment: Avoid overhead watering, ensure proper spacing, and rotate crops annually.
Botrytis Blight:
Cause: Thrives in damp, cool conditions.
Signs: Gray, fuzzy mold on flowers or leaves.
Prevention/Treatment: Remove dead or decaying plant material promptly, maintain airflow, and consider organic fungicides if necessary.
Pests to Monitor:
Earwigs:
Cause: Seek shelter in debris and feed on tender growth, especially seedlings.
Signs: Chewed leaves and damage to young plants.
Prevention/Treatment: Use soy-oil traps or rolled-up newspaper traps. Clear debris near planting areas and use weed cloth to reduce hiding spots.
Aphids:
Cause: Thrive in clusters on stems and undersides of leaves.
Signs: Leaves curling or yellowing due to sap-sucking.
Prevention/Treatment: Use insecticidal soap, neem oil, or encourage beneficial insects like ladybugs.
Spider Mites:
Cause: Prefer dry conditions and low humidity.
Signs: Fine webbing on leaves and discoloration.
Prevention/Treatment: Mist plants to increase humidity and introduce predatory mites.
Leafhoppers:
Cause: Transmit diseases like aster yellows.
Signs: Yellowing leaves and stunted growth.
Prevention/Treatment: Use sticky traps, row covers, and companion planting to deter pests.
Japanese Beetles:
Cause: Feed on foliage and flowers.
Signs: Chewed leaves and petals.
Prevention/Treatment: Handpick beetles in early morning and dispose of them in soapy water. Use row covers during peak activity.
General Prevention Tips:
Healthy Soil:
Build soil health with compost and crop rotation. Avoid overuse of high-nitrogen fertilizers, which can promote lush, weak growth susceptible to pests and diseases.Weed Management:
Keep beds clean with weed cloth or silage tarping to minimize pest habitats.Airflow and Spacing:
Space plants to promote airflow and reduce humidity around leaves, tailoring spacing to your growing conditions.Early Monitoring:
Regularly inspect plants for early signs of issues and address them promptly to prevent escalation.
By incorporating these practices, zinnias can thrive even in the face of common challenges. Whether it’s protecting against powdery mildew or battling aphids, proactive care ensures a vibrant, productive zinnia patch all season long.
A cheerful harvest of vibrant zinnias ready for bouquets and arrangem
Harvesting and Post-Handling Zinnias
Zinnias are a productive crop with a reliable vase life of 7–10 days when handled correctly. By mastering proper harvesting and post-handling techniques, flower farmers can ensure their zinnias reach customers in top condition and are easy to care for.
Optimal Harvesting Practices
When to Harvest:
Harvest zinnias when blooms are fully open, as buds won’t continue to develop once cut.
Perform the “wiggle test”: Shake the stem gently near the base. If it remains firm, it’s ready to harvest.
Deep Cuts for Continuous Growth:
Cut stems deeply, just above a leaf node, to encourage longer stems and additional blooms throughout the season.
Handle with Care:
Zinnias’ hollow stems make them prone to bending or “breaking necks.” Handle gently and avoid overcrowding stems in buckets.
Best Harvest Time:
Harvest in the cool of the morning or evening when plants are hydrated and temperatures are lower to reduce stress on the blooms.
Post-Handling Tips
Hydration:
Place stems immediately into clean water with a CVBN tablet to minimize bacteria growth.
Re-cut stems at a 45° angle to maximize water uptake.
Cooler Storage:
Zinnias are cold-sensitive. Store them in a cooler set between 45–50°F, avoiding temperatures below 40°F.
Use zinnias promptly; they perform best when not stored for extended periods.
Maintaining Vase Life:
Encourage customers to change water daily and re-cut stems every 1–2 days.
Avoid commercial flower food, as zinnias don’t respond well to it. Clean water is sufficient.
Educating Customers
Flower farmers should provide care tips for zinnias, as their vibrant blooms require regular maintenance for optimal vase life. When selling to customers or florists:
Emphasize the importance of daily water changes and fresh cuts to extend vase life.
Educate customers that zinnias are “dirty flowers” and keeping water clean is key to preventing cloudy vases.
Highlight the benefits of locally sourced zinnias, which are fresher and more robust than imported options.
For florist customers who are not familiar with zinnias, encourage them not to place zinnias in the cooler.
By sharing this knowledge, farmers can enhance the customer experience and build loyalty for their locally grown blooms.
Zinnias shine in farm-to-table designs, paired with dahlias, lisianthus, and unexpected greenery like tomato sprigs.
Designing with Zinnias
Zinnias bring vibrant color, texture, and versatility to floral designs, making them a go-to choice for bouquets, centerpieces, and event florals. However, their hollow stems and water needs require thoughtful handling to ensure they stay fresh and vibrant in arrangements.
Design Tips
Water Source is Key:
Zinnias require a consistent water source to maintain their structure and appearance. Use a vase, water tube, or floral foam substitute (like agrafoam) in your designs to keep them hydrated. Avoid using zinnias in designs where they won’t have access to water, such as wearables or hanging installations, as they wilt quickly out of water.For bridal bouquets and event work, provide a water source, such as a hidden vase or vessel, for the arrangements to rest in between use. This simple step ensures the flowers stay fresh throughout the event.
Combining Colors and Sizes:
Leverage zinnias’ diverse palette and sizes to create dynamic designs.
Pair smaller varieties like Persian Carpet or Oklahoma with larger, show-stopping blooms like Benary’s Giants for depth and texture.
Use their bright, cheerful hues for casual summer arrangements or softer tones for weddings and events.
Care in Handling:
Zinnias’ hollow stems are prone to bending, so handle stems gently while arranging. Avoid placing heavy flowers on top of zinnias to prevent damage.Event Use:
Zinnias are perfect for adding bold pops of color to event florals. Their natural resilience to summer heat (when hydrated) makes them an excellent choice for outdoor events.
Favorite Pairings
Zinnias pair beautifully with other field-grown flowers, enhancing their texture and vibrancy. Some of our favorite combinations include:
Dahlias: The bold, structured blooms of dahlias balance perfectly with zinnias’ playful petals.
Cosmos: Add a touch of whimsy with the delicate, fluttering petals of cosmos.
Scented Geraniums: Use their textured foliage and soft fragrance to elevate arrangements and add depth.
Want to cultivate more whimsy in your garden? Check out our Cosmos Cultivation blog over on Bootstrap Farmer for tips on growing and designing with this versatile flower.
Design Applications
Bouquets:
Zinnias shine as both focal flowers and fillers in hand-tied bouquets. Their long stems make them easy to arrange and add movement to the design.Bud Vases:
Single-stem bud vases are a great way to showcase zinnias’ beauty, especially for smaller varieties like Lilliput or Persian Carpet.Wildflower-Inspired Designs:
Zinnias’ bright colors and playful textures work wonderfully in garden-style or wildflower-inspired arrangements.
By following these tips, providing water sources for event florals, and experimenting with complementary flowers, zinnias can become a staple in any designer’s toolbox, adding both charm and versatility to every arrangement.
A final flourish of freshly harvested pink zinnias from the vibrant summer patch.
Saying Goodbye to Zinnias
As much as we cherish the abundant blooms of zinnias throughout the growing season, there comes a time when their production slows or the plants show signs of decline. Knowing when to say goodbye ensures your garden remains productive and ready for the next crop.
Signs Your Zinnias Are Finished
Reduced Flower Production:
As the season progresses, zinnia plants may produce fewer blooms or smaller flowers, indicating they’re nearing the end of their cycle.Increased Pest or Disease Pressure:
Late in the season, pests like aphids or diseases like powdery mildew can overwhelm plants, making them less productive and harder to manage.Yellowing or Browning Leaves:
As plants age, their foliage may start yellowing or browning, especially at the base, signaling that their time is up.Weak or Leggy Growth:
Over time, stems may become leggy and less sturdy, reducing their overall quality for cut flowers.
End-of-Season Maintenance
Removing Spent Plants:
If a killing frost doesn’t take the zinnias first, pull the plants once production declines significantly. This prevents pests or diseases from lingering in the garden and prepares the space for the next crop.Composting:
Healthy plant material can be added to your compost pile, but avoid composting plants heavily infested with pests or diseases to prevent spreading issues next season.Preparing for the Next Crop:
Zinnia beds can transition beautifully to other crops, such as winter-hardy greens or a cover crop to improve soil health. If transitioning to additional summer crops, consider planting fast-growing crops such as single-stem sunflowers
Prolonging Their Season
If frost threatens early, covering zinnias with low tunnels or frost cloth can buy extra time for blooms, especially for late-season markets or events. However, once they stop producing quality blooms, it’s best to move on and focus on preparing for the next season.
Harvested beauties nestled into a vintage sap bucket, surrounded by the thriving zinnia field.
A Season of Vibrance: The Zinnia's Legacy
Zinnias are more than just a reliable crop for flower farmers—they're a celebration of summer’s vibrancy, resilience, and beauty. From their bold colors to their prolific blooms, these hardworking flowers have rightfully earned their place as one of the top five favorites in the field.
Whether you're a seasoned grower or planting zinnias for the first time, the lessons they teach about productivity, adaptability, and artistry are invaluable. They fill fields, bouquets, and hearts with joy, making them a cornerstone crop for any flower farmer aiming to bring the best to their community.
What’s Next? Love summer’s bold and beautiful blooms? Check out our blog on Dahlias and discover how these stunning flowers complement zinnias in the field and in design.
We are looking forward to sharing more blooms with you soon.
Jessica & Graham
