How to Grow Zinnias From Seed

It’s almost too good to be true: beautiful flowers that are affordable, easy to grow, and will allow you to cut armfuls of gorgeous blooms all summer long.

Here’s how to grow zinnias from seed and what you need to do to care for them well.

If you’re looking for a burst of homegrown cut flowers to add to your kitchen counter or bedroom tables without a lot of hassle or care, then zinnias are just the thing. You basically plant seeds, wait, and enjoy.

They will add bright colors that scream summer: pink, red, yellow, green, orange, and white. You’ll see a variety of shapes, heights, and types of flowers…from tiny Thumbelina to Benary’s giant series.

 Why You’ll Love Growing Zinnias

• They attract hummingbirds and butterflies: a group of these colorful blooms will be a light to invite butterflies to your area.
• The flowers bloom all the way up to frost
• If you keep cutting, you’ll have more blooms than you know what to do with
• They’re a great choice for warmer climates

Zinnia Facts

 Zinnia flowers (official name Zinnia Elegans) are in the Asteraceae family and are native to Mexico. These flowers are a frost-sensitive annual. Therefore they won’t return year after year and must be sown in the soil after the last frost.

 Zinnias require total sun exposure and bloom from summer to the first frost date.

Gardeners love Zinnias because they are easy to grow from seed. They attract beneficial pollinators, can be used as a stunning cut flower, tolerate summer heat, survive pesky deer, and are good in containers.

Step 1: Pick Your Varieties

Zinnias come in various heights, from short varieties perfect for borders to taller ones like California Giants Zinnias, which are ideal for the back of garden beds.

There are different varieties of zinnias, including double flowers, which provide a fuller look, and single flowers, which have a simpler, classic appearance.

Some of my favorites:

• Benary’s Giant This is a classic choice, with big flower heads and a huge variety of colors. If you’re overwhelmed by choices, pick a Benary’s giant mix.
• Fireball blends are varieties in the red, orange, and yellow color scheme.
• California Giants are varieties in the red, rose, yellow, and orange color scheme. They grow tall and are the first of the varieties to bloom. California giant flowers and blooms are similar to dahlia flowers with tall stems and large double blooms.
• Cactus Flower Blend Cactus Zinnia flowers have rolling, feathery petals and are absolutely spectacular in bouquets or as garden adornments. This zinnia blend is 4″–6″ wide making it one of the largest zinnias available! Double and semi-double blooms in brilliant shades of pink, white, red, orange, and yellow. The petals are long with rolled edges that turn and twist. Each individual flower lasts a long time on the plant and in the vase. Zinnias are edible but have little flavor. The colorful flowers can make a pretty garnish for salads, desserts, cold drinks, or serving trays. The Cactus variety is very tall, the blooms are very large, and the pollinators absolutely love them. Wide range of beautiful colors, but not garishly bright. Makes a beautiful bouquet. Highly recommended by many gardeners including beginners.
• Cupcake Blend Cupcake blends are beautiful varieties of the Zinnia that resemble Scambiosa. The crested center ruffles and unfolds and looks like a cone-shaped once fully in bloom.
• Thumbelina These varieties are perfect for borders as they are dwarf and spread with single or semi-double smaller flowers in all sorts of colors.
• Peppermint Stick Peppermint zinnias are a fun and playful variety to grow. Growing 2 – 4 inches tall, these striped and speckled flowers come in delightful, cheery colors.
• Polar Bear. The white varieties such as the polar bear of the zinnia flower are beautiful and go well in cut flower bouquets with greenery and sprigs of lavender.

Step 2: Decide on a Location and Prepare It for Planting

In some ways, this truly is as basic as “stick seeds in the ground and wait for the flowers to bloom” but of course, there’s a little more to know for the best results.

Choosing a Good Location

Zinnias grow well anywhere, but they do need full sun. (This means 6-8. hours of sun per day, so some afternoon shade is fine, and often appreciated). Here are some great places to put them:

• Border Backdrop. Try adding tall zinnia varieties as a backdrop in your flower garden plan. Use short zinnia varieties along perennial borders.
•  Butterfly Garden. Zinnias are a great addition to an annual butterfly garden amongst other flowers such as milkweed. Attracting honeybees and butterflies are a critical sustainable practice to consider when gardening not only for yourself but to improve nature and the natural landscape.
• Containers. Zinnia plants also thrive when grown in containers. Smaller varieties make good potted plants for your porch or deck. Choose a clean container with drainage holes.
• In The Vegetable Patch. Zinnias make great companion plants in a vegetable garden. They attract beneficial pollinators and can be planted alongside crops like zucchini, beans, and chard.

Zinnias are lovely in their own cut flower garden, amongst perennial garden spaces as borders and even as companion plants to vegetables such as zucchini, beans, and chard.

Prepping the Soil

This is quite minimal, but you do need to make sure there’s good drainage.

Prepare the garden bed by cultivating and loosening soil. The young plants are sensitive to cold, and soil temperatures should be in the 50s or 60s before transplanting.

Zinnias do not need rich soil, but a light fertilizer application or a good amount of compost will result in healthier plant.

A Note About Starting Seeds vs Direct Sowing

Either one works! I always direct sow because it’s so much easier and I’m not in a hurry. But, if you have a short growing season or want extra-early blooms, you can certainly start yours indoors.

Starting Seeds Indoors

If you’d like an extra-early start on your blooms, you can plant zinnia seeds under fluorescent plant lights, either in trays, peat pots, or soil blocks. Put them on a heat mat, keep the soil moist, and the zinnias will germinate quickly (within five days).

You can start four to six weeks before your average last frost date. Transplant outdoors after the last frost date. Most gardeners choose not to start seeds indoors as there is no benefit from being sown early and prefer to wait for warmer weather.

They grow quickly, so be prepared to move them into the garden within a few weeks (don’t start them too early!)

Step 3: Plant Your Seeds or Transplants!

 Soaking zinnia seeds before planting for about 12-24 hours will help reduce germination time.

 Sow zinnia seeds about ¼ inch deep and lightly water after planting. After about a week, you’ll see seedlings emerge from the soil.

The average spacing is 6 inches between plants in the row and two feet between the rows for most zinnia varieties. (But check the seed packet!)

(If you’re planting zinnia seedlings, space them at the recommended distance that plants will be after thinning.)

The best place to find the exact information for spacing distances and seed sowing depths is always on the back of the seed packet. Larger varieties will need more space, and dwarf types can be closer together.

Step 4: Care for Them as They Grow

We’ve already discussed that zinnias are easy to grow, but they will need a few things from you.

Once your seeds have germinated, and the plants are about 6 inches tall, spread organic mulch around them to preserve soil moisture. You don’t have to do this, but it will make weeding easier and you won’t have to water as much.

Thinning: Once the seedlings reach three inches tall, it’s essential to thin them to about 6 to 18 inches apart to allow air circulation and preventative disease control. When thinning seedlings, try adding the seedlings you are removing from the patch to the end of the row to expand your final garden bed. To do this, you’ll have to make sure that you don’t disrupt the roots.

Pinching: Pinch young plants when they are about 12 inches tall. Pinch directly above the leaves, and two stems will form where there was one. Pinching strategically will give you more flowers. You can keep pinching throughout the growing season, and each pinch will produce blooms that you wouldn’t have otherwise had.

Watering: Zinnias will survive with less water than other plants, but that doesn’t mean they like it. They’ll still do best with an inch of water per inch and a little extra on very hot days.

Powdery mildew: Zinnias will often get powdery mildew, especially later in the season when mornings are cool and damp. Give your plants plenty of good air circulation and choose disease-resistant varieties to combat this. But powdery mildew is just a nuisance, and since it usually happens at the end of the season, you can pull the plants that are badly affected.

Other diseases: Your zinnias are less susceptible to bacterial and fungal spots and wilt. The best way to prevent the disease from bothering your beautiful flowers is to water at the base of the plants in the soil and minimize getting the foliage wet.

If you’ve correctly spaced out the plants and are watering the roots in the morning, your zinnias should be healthy and happy.

Pests: Japanese beetles may nibble on the leaves, but they rarely cause severe damage. One thing you will not have to worry about when keeping your zinnias cared for and thriving is deer. Wildlife is always a concern for most plants, but lucky for the zinnia, they are deer resistant. (Of course, a deer who is hungry enough will eat anything, but they don’t find zinnias particularly delicious)

Fertilizing. If you’re noticing that you’re not getting the blooms you expected from your Zinnia’s, try giving the plants some fertilizer. A fertilizer rich in phosphorous such as bone meal will help encourage blooms.

Deadheading. Use clean garden snippers to deadhead plants by cutting off old flowers to encourage more flowers to form.

Zinnias will take 60 to 70 days from being sown in the soil producing mature flowers (depending on the conditions and the variety).

Step 5: Harvest and Enjoy

Make sure to cut and enjoy your zinnias in bouquets, vases, and flower arrangements all throughout the summer months. Remember that by cutting flowers, you’ll encourage new blooms to form throughout the season.

When harvesting zinnias for a cut flower bouquet or vase, make sure to harvest before small yellow flowers emerge between the petals.

• Harvest after the morning dew has dried, but before the heat of the day
• Cut long flower stems, deep into the plant, at a 45-degree angle
• Let cutting flowers sit in a bucket of cool water for a few hours before arranging
• Treat water with a floral preservative for the longest vase life

Step 6: Save Seeds and Wrap Up the Season

Zinnias are annuals, meaning they complete their life cycle in one growing season and do not survive through winter. You’ll need to plant new seeds next spring.

The good news is, you can save seeds from your zinnias for planting the following year. Harvest the seeds from the dried flower heads and store them in a cool, dry place.

It’s easy to save seeds from open-pollinated varieties such as candy cane and California giant.

Wait for the zinnia flowers to dry before harvesting. Place harvested seed heads on a screen so they can dry all the way around. Remove the seeds over a labeled piece of paper and allow them to dry further.

Place the seeds in a cool, dry place such as a brown paper page in a closet. Don’t forget to label the bag and use it within a few years.

FAQs: Common Questions About Growing Zinnias

Nothing says mid-summer like a bouquet of zinnias in the kitchen. You really cannot go wrong when choosing to add zinnias to your landscape. I hope they bring a smile to your face this year. ❤️