How to Grow and Care for Zinnias

If you’re looking for an annual flower that’s easy to grow and will add a stunning burst of color to your garden, look no further than zinnias.

Zinnias are a staple at garden centers and also incredibly easy to grow from seed. They make beautiful cut flowers and bloom prolifically. And there’s a huge range of shapes, sizes, and colors to choose from.

Here’s more about this beautiful annual, plus how to grow and care for zinnias.

What Are Zinnias?

Zinnias belong to the aster family, which means they are plant relatives to other flowers like daisies, marigolds, and sunflowers.

Originally native to the grasslands of the southwestern U.S. and parts of Mexico and South America, zinnias are widely grown as annuals all around the world. Plants bloom with bright and cheerful flowers in a wide variety of colors.

Loved by humans and butterflies alike, zinnias are one of the easiest annual flowers to grow. They will grace your garden with bright, cheerful blooms that continue until the first frost.

Zinnias can be grown during the summer in most USDA hardiness zones but may struggle with them in areas with cold and wet summers. When happy, the plants will bloom all the way from early or mid summer until the first frost.

Benefits of Growing Zinnias

Easy to grow and low maintenance, zinnias are one of the most popular annuals for a reason. There are both large and small varieties, with the smallest being 6-8 inches tall and the largest growing up to 4 feet tall.

Not only do they look lovely in garden beds, containers, window boxes, and borders, zinnias also attract bees, butterflies, hummingbirds, and songbirds.

Monarch butterflies, in particular, are attracted to the nectar of zinnia flowers, making them a great addition to a pollinator or butterfly garden. Plants grow quickly and are drought- and deer-resistant once established.

Butterflies love the nectar provided by zinnias, and many other pollinators are attracted to the flowers as well. You’re also likely to see hummingbirds and songbirds stop by throughout the season.

There is an almost endless variety when it comes to color choice, and the flowers are perfect for cutting and adding to arrangements or bouquets.

Types of Zinnias

There are hundreds of varieties of zinnias but only three main types of flowers and several types of flower shape. Here’s a look at the main ones:

• Single-flowered– This type has a single row of petals and a clearly visible center, giving them a daisy-like appearance.
• Double-flowered– This type of zinnia has several rows of petals. The center is not visible, giving them more of a ball shape.
• Semi-double– This type is halfway between the two previous ones. There are several rows of petals, but the center is still clearly visible.
• Cactus– Cactus zinnias have longer, thinner petals than other varieties with some being almost needle-like. Flower heads are typically larger as well and double or semi-double.
• Button– Button blooms are small and round (just like buttons). The plants are usually compact with dwarf button varieties being a great choice for small spaces and containers.

Dahlia zinnias have blooms that look remarkably similar to dahlia flowers. This type makes a statement with its large and showy blooms and makes a great cut flower.

• Beehive– These ones are named because they have stacks of flat petals that make them look like beehives. Blooms are typically more rounded than button types.
• Dahlia– These are so named because the large blooms resemble dahlia flowers. Typically single or double-flowered and makes long-lasting cut flowers.

Zinnia Varieties

There are several different species of zinnias, but the most commonly grown is Zinnia elegans (also known as common zinnia).

There are many outstanding varieties and cultivars but usually a limited selection at garden centers. If you want a larger variety to choose from, try growing your plants from seed.

Here are a few cultivars to keep in mind:

• ‘Benary’s Giant’– This is one of the best and most popular series of giant zinnias. The double blooms of this cultivar can be up to 6 inches across and are standouts in cut flower arrangements. The plants themselves are also large, growing up to 4 feet tall. Choose from a wide range of colors: coral, deep red, scarlet, orange, lime, pink, yellow, and more. Or buy a mixed packet of seeds to get a rainbow selection.
• ‘Dreamland’– On the other hand, this is one of the most popular dwarf series. Plants are very compact, growing only 12 inches tall max. The flowers, however, are full size and reach up to 4 inches across. You can choose the color you like or get a mix.

There are hundreds of unique zinnia cultivars. ‘Peppermint Stick’ is a fun variety to grow because blooms resemble striped candies and look as if the pattern was painted on the petals.

• ‘Queeny Lime Orange’– This is a very unique cultivar with blooms that gradually go through shades of coral, orange, lime, and peach. Bloom centers are dark pink, and plants grow up to 2 feet tall.
• ‘Señorita’– Senorita is a showy, double-flowering cactus zinnia with salmon-pink petals that curl up at the ends. They can get up to 3 feet tall and are lovely in bouquets.
• ‘Profusion’– This hybrid cultivar comes from a cross between Zinnia elegans and Zinnia angustifolia. True to its name, plants produce tons of flowers with both single and double blooms. This is a mid-sized zinnia, growing about 18 inches tall, and has better resistance to powdery mildew. A wide range of colors is available.
• ‘Peppermint Stick’– Blooms are small on this cultivar (about 2 inches), but they have a unique and brightly striped pattern. Flower heads are cream or yellow and have stripes ranging from red to purple to orange. Some also have speckles and splotches, which gives you one-of-a-kind patterns. Plants grow 2-3 feet tall.

How to Grow Zinnias

Zinnias are one of the easiest annuals to grow- as long as you don’t plant them in cold weather. You can buy them in packs from your local garden center or nursery or start them yourself from seed.

Starting from Seed Indoors

Many gardeners like to get a headstart on their zinnias by sowing seeds indoors in spring. You’ll want to start your seeds about 4-6 weeks before your average last frost date.

Zinnias do not do well with being transplanted because they don’t like their roots disturbed. The best way to work around this is to sow seeds in peat pots or another type of biodegradable pot so that you can plant the containers in the ground without touching the roots.

Before getting started, soak your peat pots in water for just a minute or hold them under running water so that they aren’t bone dry.

Then, get a good quality seed starting mix and add enough water to it so that it’s damp and clumps together but isn’t soaking wet. Fill up your peat pots with soil mix nearly to the top and place them in a tray.

Make a shallow indent in the soil of each pot with your finger about ¼ inch deep. Put a zinnia seed into each indent and cover them lightly with more soil.

Keep the pots watered and in a warm spot while the seeds germinate, which takes about a week. Once your seedlings start popping up, place them under grow lights or by a very sunny window.

You’ll want to regularly run a fan on your seedlings for 10-15 minutes at a time. The airflow helps prevent plant pathogens from growing that zinnias can be susceptible to.

Starting from Seed Outdoors

Zinnia seeds are also easy to start directly in the garden. This method means your plants will bloom later than those started indoors, but you don’t have to worry about transplanting.

Zinnias are easy to grow from seed indoors or right in your garden. Starting from seed also gives you a lot more choices for shape, size, color, etc. Try a few different varieties to see which ones you like best!

Plan out the areas you want your zinnias to grow in, since digging up and moving the plants later will likely be unsuccessful. Wait until well after the last frost when soil temperature has warmed up considerably (about the same time you’d plant peppers).

Work the soil where you’ll be sowing seeds by raking it out and breaking up any clumps. Add some compost to your soil to give your zinnias nutrients later on in the season.

Follow the directions on your seed packet, but most zinnia seeds get planted about ¼ inch deep. Sow the seeds in rows or clumps, cover them with soil, and water. Keep the soil damp until seeds start to germinate.

Once your seedlings are a few inches high, thin them out so that they are spaced according to the distance on the seed packet. You can pull out seedlings or cut them right at the ground with a pair of scissors or garden clippers.

Best Growing Conditions

When choosing a spot to plant your zinnias, there are a few important things to look for.

Zinnias do best in full sun and will give you the best blooms when they get enough sunshine. They can be grown in part shade, but plants may end up spindly and will bend or fall over toward the sunlight.

Zinnias thrive in full sun and may struggle in shaded areas. Plants are also prone to fungal diseases that come from damp conditions, so make sure you space plants correctly to allow for good airflow.

Choose areas that are well-drained or containers with drainage holes in the bottom. Zinnias can have problems with rotting and fungal diseases when conditions are too damp or water doesn’t drain well.

Plants will adapt to many soil types, even poor soil, but adding in some homemade compost will give your zinnias a better start, and they’ll be more likely to bloom profusely.

Make sure you follow the spacing requirements for the cultivar(s) you’re planting because good airflow will help ensure healthy plants.

Planting Your Zinnias

Once you have your seedlings and your planting locations are all planned out, it’s time to get your plants in the ground!

Remember, zinnias like warm weather. They need at least 60°F weather to start growing and prefer temperatures in the 70’s and 80’s. Although you may be tempted to plant them in your garden as soon as possible, wait until the weather warms up enough.

The spacing for your plants depends on the cultivar(s) you have. Smaller, dwarf plants can go 6-8 inches apart while the larger varieties will need at least 18 inches in between plants.

Dwarf varieties are good choices for small areas and also do well in pots and window boxes. Be gentle with plants as you put them in the ground or in containers, and disturb the roots as little as possible.

Dig holes for your zinnias that are slightly wider than the root ball and about as deep. Gently place one plant in each hole and disturb the roots as little as possible. If you have peat pots, you can simply place the whole pot into the hole.

Fill soil in around the plants so that the top of the root ball is just covered. Firm it a little with your hands, and then water all your newly planted zinnias well.

Zinnia Care

Newly planted zinnias will need to be watered regularly for the first few weeks. How often they need watered will depend on how hot it is and how quickly the soil dries out. It’s better to water deeply and less frequently than shallowly and often.

Also, make sure you water the soil around the plants and not the leaves. Keeping the foliage dry helps to prevent certain diseases like powdery mildew.

You can put a light layer of mulch around your plants to help keep moisture in the soil and weeds down. However, many zinnias are drought tolerant and will do better without any mulch.

Most varieties will do fine without any fertilizer (especially if you already mixed in some compost), but lightly fertilizing throughout the summer can encourage more blooming. Use a balanced fertilizer like a 5-5-5.

Zinnias require very little care, but deadheading spent blooms will encourage plants to keep sending out flowers. A light fertilizer every month or two can also increase blooming.

Some varieties are self-cleaning, but most zinnias will benefit from deadheading. This simply means that you remove dead or spent flower heads to encourage more blooming later on.

Seed Saving

Although they are annuals, it’s very easy to save zinnia seeds to plant again next year.

Let the flower head fully mature and dry on the stem (rather than deadheading). Snip them off and let them sit on a paper towel for a few days to make sure they’re fully dry.

Then, separate out the seeds by lightly crushing the flower heads and sifting out the debris. Store in a seed packet and place in a cool, dry place over the winter.

You can get a good variety of zinnias this way, but keep in mind that hybrid varieties likely won’t come true from seed. You’re likely to end up with surprise colors, shapes, and patterns!

Pests and Diseases

Zinnias can be susceptible to fungal diseases, especially powdery mildew. The best way to keep plants healthy is by taking preventative measures.

Space plants at the recommended distance so that they all have good airflow. Try not to get the foliage wet when you water plants and make sure they are in full sun.

Zinnia plants are susceptible to fungal diseases like powdery mildew that can turn leaves white and weaken the plants. Use preventative measures or a spray like Serenade to naturally control fungal pathogens.

You can also apply some preventative sprays, especially during humid weather. Use neem oil or an organic spray like Serenade. After powdery mildew appears, you can spray with Serenade or a mixture of soap, baking soda, and water.

Aphids are another garden pest that can show up on zinnias. You can knock them off with a strong blast from your garden hose or use a natural spray for a more severe infestation.

Japanese beetles also appear sometime in mid-summer and like to snack on zinnias. You can place beetle traps a good distance away from your plants to divert them from your garden. Or pick the beetles off by hand and drop them in soapy water.

Zinnia Tips and Companion Plants

Here are a few last tips for growing zinnias, plus some ideas of what to plant them with:

• To keep the show going all summer, stagger your zinnia plantings. You can start with transplants and then sow seeds every 2-3 weeks to make sure you have continuous blooms through the fall.
• Make a beautiful cut flower garden by planting zinnias with plants like cosmos, marigolds, dahlias, and asters.

Zinnias are a great addition to a flower bouquet. Grow them in a cut flower garden with plants like sunflowers, cosmos, daisies, and dahlias.

• Combine the showy blooms of zinnias with the lovely subtlety of ornamental grasses for a display that will last well into fall.
• Zinnias add color and a source of nectar to pollinator and butterfly gardens. Plant them with other annuals or with native and pollinator-friendly perennials like purple coneflower, milkweed, butterfly weed, Rudbeckias, and bee balm.
• Compact zinnia varieties make a great addition to window boxes, containers, and even hanging baskets. They also make good edging plants. Mid-sized and larger varieties can be grown in the middle or back of a border or planted in clumps for a vibrant display.

Zinnias make a cheerful and low-maintenance addition to any garden. There’s sure to be a variety and color to suit what you’re looking for.

If you want to try out a unique and brightly colored plant to go with zinnias, check out this guide to growing ornamental peppers.