11 Tips for Growing Beautiful Zinnias in Pots

Zinnias are a flower grower's dream with their long bloom season, range of color options, and ability to grow well on patios in containers or raised beds. Today, there are cultivars explicitly bred for container growing, so if you have containers you want to fill up with flowers, look no further than zinnias. Join small-scale farming expert Jenna Rich to discuss some tips and tricks to grow beautiful zinnias in containers.

Zinnias are widely revered as a bright and cheery annual flower option, easy to grow in many different soil types. They work well as border flowers, and their height makes them perfect for the backdrop to landscaped plants. However, they look cute as can be in patio containers that you can move around to follow the sun or accent seating areas. If you want to grow zinnias in pots, we’re here to help with some easy tips!  

Here are 11 simple things you can do to grow beautiful zinnias in containers

Contents

Start From Seed

Close-up of a starter seed tray with germinated Zinnias seeds, near a sunny window. Seedlings are small, consist of thin vertical stems and a pair of small oval green leaves.
Starting zinnias from seed is simple due to their large size and high germination rate.

Zinnia seeds are pretty large, and most varieties offer a high germination rate, so starting them from seed is an easy choice. You can either start them indoors in cells and then transplant them into a pot a few weeks later or sow them directly into the container of your choice. You choose!

If you direct-sow them in a pot, space them according to your pot size. Since they are a bit larger, bury them about a ½ inch down. Do not start any sooner than six weeks before your last possible spring frost. This will allow them to mature enough before planting outside but not long enough to become rootbound or stressed. 

Seeds will germinate within 5-7 days when the soil temperature is between 74-80°, and even quicker when heat mats are used. Water the seeds in well, but do not fully saturate the soil. 

Do not transplant zinnias into outside soil until temperatures are consistently over 60° to reduce the risk of transplant shock. 

Select Appropriate Varieties 

Close-up of blooming Yellow Pink Profusion Zinnia in a black clay pot, in the garden. This is a compact stort of zinnia with medium ovate dark green leaves. The flowers are a unique two-tone combination of yellow and pink, creating a striking visual contrast. The flowers are daisy-like, consisting of two layers of oval petals surrounding a central disc. This disk is made up of tiny tubular florets.
It is recommended to purchase seeds from reputable sources.

If you are new to zinnias and want to grow them in pots, one of my no-fail favorites is ‘Benary’s Giant Blend.’ This will allow you to see all the colors Benary’s provides and pick your favorites for next season. These stems can get quite tall, so be prepared with a properly sized container offering some support with enough room to space them properly.   

If you’d prefer a more compact zinnia to grow in pots, the award-winning ‘Profusion’ series is a bushier, colorful option that will turn heads. 

The ‘Cactus Zinnia Flower’ offers a funky look and adds visual interest to your front stoop or back patio. Furthermore, ‘Double Zahara™ Brilliant Mix’ is a new, mum-like zinnia perfect for bred for powdery mildew resistance. 

Whatever variety you select, only purchase seeds from a reputable source. 

Use Proper Potting Soil

Top view, close-up of a small flowering zinnia seedling against a white table and a scattered pile of soil with a garden shovel. The zinnia forms a medium lush flower consisting of many layers of small oval pink petals surrounding tiny yellow tubular inflorescences in the center. The leaves are lanceolate, slightly hairy, green.
Choose a nutrient-rich, well-draining mix, and add absorbent materials like vermiculite or peat moss.

Use something with well-balanced nutrients that can drain well. Feel free to add something absorbent, such as vermiculite or peat moss, to help store moisture.

Mixing in well-aged manure or compost is helpful when growing zinnias in pots, as they are moderate feeders and are in the ground for quite a while. 

Choose An Appropriate Container

Close-up of blooming orange zinnias in a large black plastic pot, outdoors. This flowering plant produces semi-double, bright, orange flowers with several layers of petals surrounding a central eye made up of tiny tubular flowers. The leaves are medium, lanceolate, dark green.
There are a wealth of options for planting your zinnias in containers.

Today’s gardeners have so many more options than just window boxes or ceramic pots. To grow zinnias in pots, you need the right vessel. Here are some of my favorites:

  • Grow bags have become very popular over the past few years due to their built-in drainage material, ease of moving, and durability. The water drains right out, so it’s nearly impossible to overwater. Most bags on the market offer handles that make it easy to move around your potted plants or move them inside during inclement weather. 
  • Permanent raised beds are a gardener’s new best friend. I use them at our farm to keep herbs like mint and oregano from spreading, but they’re also perfect for annual flowers. Growing in raised beds provides increased soil health, improved drainage, a clean look, and less bending over to harvest.
  • Hanging baskets add dimension and height to any garden display. Try growing a shorter cultivar and something that will hang over the sides to add a little drama. 
  • Classic ceramic pots are still great to grow in! These add a little class to a patio or outdoor landscape. There are also BPA-free plastic pots with a bottom-watering tray that’s perfect if you have to leave your plants to fend for themselves for a few days. 

<strong data-rich-text-format-boundary=”true”>Pro tip: </strong>Do you want your patio arrangements to look intentional and pleasing to the eye? Grouping pots in odd numbers of three or more adds a harmonious look to your outdoor living space.

Choose A Good Location 

Close-up of blooming zinnias in clay hanging pots on a sunny balcony. The flowers are small, semi-double, bright pink in color with central discs of yellow tubular inflorescences. The leaves are lanceolate, bright green in color, covered with small white hairs.
Zinnias thrive in full sun, tolerating partial shade, making great borders or pot placements around your yard.

Zinnias will thrive in full sun out of harm’s way from strong winds. However, partial shade will be just fine as well.

As previously mentioned, zinnias make a great border wall planting and look lovely along the outer edge of a small flower plot. If you grow zinnias in pots, you can show them off on the front porch, back patio, or even in garden beds. Move them around occasionally for fun! 

Pinch Back When Plants Are Young And Deadhead Often

Close-up of male hands in blue latex gloves about to prune a blooming zinnia flower in a garden, against a blurred green background. The flower grows on a long thin stem. It is daisy-like in shape, consisting of bright pink petals surrounding a central inflorescence of small yellow tubular flowers.
Pinching back young zinnias before transplanting encourages bushier growth.

It may seem counterintuitive to pinch back young plants waiting to be transplanted. However, think of pinching back your zinnias to encourage them to get established, send out side shoots, and prepare them for a long season of abundant, continuous blooms.

Studies have shown that pinching back in certain cultivars also creates a bushy, shorter plant with thicker stems, which is ideal when growing in containers. Sometimes, cutting down what seems like a perfectly good flower seems sacrilegious, but you’re paying it forward to your future garden.

Deadheading refers to cutting back unwanted, misshapen, or passed-by flowers. If too many days have passed or lots of rain browns your flowers, go through with a pair of sharp snips and cut them down to above a node near the base. Keep at least two sets of leaves intact to ensure future growth.

Cutting back in this way will not only clean up your flower patch but also creates more airflow and provides a space for new blooms. In about a week or so, you should start to see new blooms appearing. And just like that, your zinnias are freshened up!  

Water Regularly 

Watering flowering zinnias from a green watering can in a sunny garden. The plant produces lush, bright green, lanceolate, slightly hairy foliage. The flowers are semi-double, pompon-shaped, composed of many layers of petals ranging from soft peach to rich pink and red, surrounding a central cluster of tiny yellow tubular flowers.
Provide about an inch of water per week, especially in sunny locations.

Zinnias are pretty low-maintenance regarding water since they do not require much, about an inch per week. But, since zinnias love to be in full sun and love the heat, pay close attention to their water levels and don’t let them dry, especially if you grow in a hot and sunny climate.

The thing to remember when growing zinnias in pots is that the roots have no place to reach down in search of water. They are solely relying on you for care. 

Water at the base of plants, preferably in the early morning versus at night. This will allow plants time to soak in the water and dry out during the day since fungal disease can spread in wet conditions.

During hot spells, water twice daily. Do the finger test if you’re unsure if your zinnias need to be watered. If the soil feels dry about two inches down, they need water.

Pro tip: If you have a lot of containers to water, lay a soaker hose over the top of them at the plant base for efficient, simultaneous watering. Keep the leaves from getting saturated to help keep disease pressure down.

Pest Control 

Close-up of a Japanese beetle on a blooming zinnia flower. The Japanese beetle (Popillia japonica) is a small insect known for its metallic green body with copper brown wings. These wing covers have a series of white tufts along their edges, creating a unique pattern. The Japanese beetle's head is a shiny metallic green color, and it features prominent white tufts of hair along the sides of its body.
Use traps or soap water to deter beetles.

Zinnias may be one of the easier annual flowers to grow, but they certainly come with their pests. Japanese beetles LOVE to munch on zinnia leaves and flowers. In fact, it’s one of their favorite things to do.

If you have used Japanese beetle traps before, try hanging one near your zinnias, but not directly next to them. This way, as they head toward their snack, the lure of the trap will be stronger, hopefully diverting them. 

Alternatively, keep a jar full of soap water nearby and hand-pick the beetles each morning, dropping the beetles into the jar. Then, dust the plants lightly with diatomaceous earth. This should deter them from landing on your plants or luring other beetles to your zinnias for mating. 

You may also encounter spider mites and aphids, which can usually be controlled by spraying your plants with insecticidal soap.  

Fertilize 

Flower seedlings of flowering zinnia in multi-colored flower pots, in a sunny garden. Zinnia seedlings have upright stems with lanceolate bright green leaves and semi-double daisy-like flowers at the tops of the stems. The flower heads consist of several layers of bright yellow to bright red, peach and pink oval petals surrounding central discs of small tubular florets.
Feed with phosphorus-rich fertilizer monthly for consistent blooming and plant health.

When transplanting zinnias, mix a tablespoon of bone meal into the top few inches of soil. This will direct the focus beneath the soil and encourage a strong root system. 

Zinnias will benefit from a monthly feed of fertilizer that’s higher in phosphorus than nitrogen to help promote continuous blooming and overall health. Healthy plants are better at fending off disease and warding off pests. However, soil testing should be done pre-season to determine the exact amount needed in your garden. 

Be On Alert For Diseases

Close-up of zinnia leaves affected by the fungal disease powdery mildew. The leaves are medium, dark green, lanceolate, covered with a white-gray powdery coating. The flower is large, daisy-like, with bright red petals and a central inflorescence of bright yellow tubular flowers.
Powdery mildew thrives in warm, dry conditions.

It’s important to know when conditions are right for disease formation and what to watch for so you can act accordingly. A few heavy hitters to be on the lookout for are: 

  • Powdery mildew will thrive in warm, dry conditions and can be identified by grayish-white spots on buds and leaves. Preventatively, space your zinnias at least a foot away from one another so there is ample airflow. If you spot powdery mildew, spray thoroughly with a copper fungicide that prevents future spread. Clear out any diseased debris, including lower leaves and flower heads, and take them to a burn pile.
  • Southern blight occurs during extended periods of wet weather and when leaves remain wet. The fungus causing Alternaria zinniae overwinters in debris or can come from contaminated seeds. Symptoms include small, reddish circles with light centers. Leaves may become brown and dry. Prevention includes good airflow, spacing out plants properly, avoiding extended wet periods, debris and weed-free gardens, and cleaning all seed-starting supplies and tools.
  • Bacterial leaf spot symptoms include small, circular purple spots on leaves which show up after extended rainfall. If spots mesh together, they may look more angular, and a yellow halo may occur. Growers can spray copper fungicide on zinnias after rainy periods to prevent the fungus from spreading and causing damage. Always spray copper in the evening. 

<strong data-rich-text-format-boundary=”true”>Pro tip: </strong>When searching for <a href=”https://www.epicgardening.com/zinnia-varieties/”>zinnia varieties</a> to grow, use the search filter to show disease-resistant options. The ‘Zahara’ and ‘Profusion’ series are great cultivars bred to be powdery mildew-resistant.

Keep Stress At A Minimum 

Top view, close-up of a blooming zinnia in a blue pot, in a sunny garden. The plant forms upright stems covered with lanceolate bright green leaves. The flower is large, semi-double, consist of several layers of pink petals.
These flowers can’t withstand frost.

Zinnias are very sensitive to cold and other environmental stressors like drought and flooding. If you start them in cell trays, do not allow them to become root-bound before transplanting them into their containers.

This could cause transplant shock, and if you have selected a double-bloom variety, they could revert back to single-blooms due to the stress, which is disappointing, to say the least. Take it from me. I have learned this first-hand! 

Zinnias will perish even after a light frost, as they have zero tolerance. As temperatures cool off in the fall months, growth and blooms will begin to slow. It’s always sad to see them go away for the season, but if you treat them well from the beginning, they will provide an abundance of brilliance all summer long. 

Final Thoughts 

Zinnias are an absolute joy to grow each season, and they range in size, color, and shape, so there is something for everyone. With the right preventative disease care and proper pruning, zinnias can grow exceptionally well in containers. Whether you have a big patio full of grow bags, a window box, or a raised metal bed, zinnias will not disappoint. 

If you haven’t grown them before, I highly recommend adding them to your next season’s seed order. Let them reseed themselves, and you might get a new crop next year, too!

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