The Ultimate Guide to Planting Zinnias: Tips and Tricks

Planting zinnias is a fun and easy way to bring a burst of color to your cut flower garden. These beautiful flowers come in various colors and sizes so you can choose the perfect zinnia for your garden.

Growing Zinnias from Seed

Zinnias (zinnia elegans) are show-stopping flowering plants and are one of the easiest flowers to grow from seed. They are available in a vast range of single blooms or double blooms, dwarf sizes, tall varieties, and colors.

The zinnia is an extraordinary bloom that brings joy to the garden. Native to Mexico, this stunning flower adds beauty to any garden beds from the beginning of summer to the first hard frost.

These beautiful plants are beloved for their hardiness and diverse range of colors, making them the perfect addition to any garden flower beds.

The zinnia’s bright petals in vibrant shades of yellow, orange, pink, and red bring a cheerful touch to any flower garden. Their long-lasting blooms make them an ideal choice for wonderful cut flowers.

Zinnias are a great choice for both beginner and experienced gardeners alike. With their easy care and long growing season, these cheerful flowers will surely bring a smile to your garden.

Here is my guide on how to grow zinnias from seed and my answer to many frequently asked questions regarding caring for zinnias.

How to Plant Zinnias

Zinnia seeds are one of the easiest to grow in the garden. It is recommended to sow their seeds directly into soil that drains well.

Zinnias are well known for their sensitivity to root disturbance, so planting them directly into the garden will ensure that their root systems are not disturbed, which is important for their growth and development.

When to Plant Zinnia Seeds

Zinnia seeds should be planted in the spring after the danger of the last frost date has passed. A soil temperature of at least 60°F is ideal for germination.

Where to Plant Zinnia Seeds

Zinnia flower seeds should be planted in a sunny spot that is well-draining and protected from strong winds. Zinnias prefer loose, nutrient-rich soil that is kept moist but not soggy.

When planting zinnia seeds outdoors, they should be covered lightly with soil and kept moist until they sprout. Zinnias should be planted in a spot with at least 6 hours of sunlight daily.

How to Plant Zinnia Seeds Outdoors

Start by selecting a sunny, well-draining location that has good soil. Once you have chosen a spot, mix some compost or other organic matter into the soil to help the zinnia seeds get off to a strong start.

When ready to plant, scatter the zinnia seeds over the soil’s surface, then gently press them into the top layer of the soil.

Water the soil lightly right after planting and keep the soil moist (but not saturated) until the seeds germinate. Once they germinate, thin the seedlings so they are spaced appropriately apart, and continue to water them regularly.

How Far Apart to Plant Zinnias

Most common zinnia seeds can be planted 8-10 inches apart within the row and 2 feet between the rows.

Depending on the variety, some seeds may need to be planted up to 24 inches apart, refer to the back of the seed packet for the most accurate information on zinnia spacing.

How Deep to Plant Zinnia Seeds

The seeds should be planted at a depth of 1/4 inch into soil that is well-draining and has organic matter added to it.

This organic material can be compost, peat moss, or even aged manure. It will help give the zinnia seedlings the nutrients they need to grow.

How to Care for Zinnias

Once the zinnia seedling has emerged from the ground, it is important to ensure they receive sufficient water and nutrients to grow.

How Much Water Do Zinnias Need?

Watering zinnias is essential to growing them and ensuring they are healthy plants. They require moist soil to grow, and this is especially true of young plants.

To keep the soil moist, deeply water them at least once a week at the base of the plants, ensuring the water penetrates 6 to 8 inches below the surface. It is important not to overwater as this can cause the plants to be susceptible to fungal disease.

Thinning Zinnia Seedlings

Once the zinnia seedlings have grown to approximately three inches tall, it is important to thin them out. Thinning seedlings should be done so that plants are placed 6 to 18 inches apart depending on the variety of zinnias.

Thinning out zinnia seedlings allows for adequate air circulation between the plants. Good air circulation is vital to keeping the zinnias healthy and reduces the risk of powdery mildew and fungal diseases.

Fertilizing Zinnias

Zinnias are known to be vigorous growers and heavy feeders. So, it is important to fertilize them to promote lush, vibrant blooms.

To ensure an optimal first spring planting, apply a balanced 10-10-10 or 6-6-6- fertilizer. Roughly use one pound of fertilizer per 100 square feet.

Additionally, a second round of fertilization in mid or late summer can help zinnias bloom until fall. Maintaining a consistent fertilization schedule ensures that your zinnias are healthy and look their best.

Pinching Zinnias

Pinching zinnias when they are young is the key to getting the longest stems. Using sharp pruners, snip the top 3 to 4 inches off the plant when it is between 8 to 12 inches tall.

This prompts the plant to produce multiple stems from the point of the cut, leading to more flowers and longer stems. This will help your zinnia plants become more abundant in their flower production.

Deadheading Zinnias

Deadheading zinnia flowers is an easy process. Start by using sharp scissors or garden clippers to remove dead flower heads or spent blooms from the plant.

Cut back the flower’s stem to just above the nearest sets of leaves. This will promote new growth and helps keep the plants healthy, and encourage more zinnia blooms and bushier plants.

Frequently Asked Questions

How to Cut Zinnias

Harvesting your zinnias at the right time for beautiful, long-lasting bouquets is essential. Hold the stem 8 inches below the bloom and shake to know if they are ready. If the stem stays stiff and upright, they are ready to be cut.

Make sure to cut just above a leaf node or bud to promote new growth on the stem. Cut the stems long and strip any foliage before immediately placing them into the water. Zinnias can last 5-7 days in a vase.

How Late Can You Plant Zinnia Seeds

The best time to plant zinnias starts in late April and continues until the beginning of July, you can plant zinnia seeds in succession to ensure a showy display until the first frost of the season.

Are Zinnias Perennials?

Zinnias are generally annuals, meaning they go from seed to flower to seed quickly. Most growing zones will not be suitable for them to be considered perennials, and they will die off after the first frost.

However, asking the question, are zinnias annuals or perennials may get you different answers depending on which USDA hardiness zone you live in.

In the warm zones from 9-11, these flowers may act as perennials and easily self-seed, growing throughout the year.

Do Zinnias Come Back Every Year?

Zinnias are annual plants, and they do not come back every year., They will grow, produce new seeds, and then die off at the end of the year.

Do Zinnias Self Seed?

Yes, zinnias can reseed themselves. If the flowers are allowed to bloom and drop their seeds into the soil, there is a strong possibility that they will sprout come the following season.

How Tall do Zinnias Grow?

Zinnias come in various heights and can grow anywhere from 1 to 4 feet tall and grow in clumps of 1 to 2 feet wide depending on the variety. Dwarf varieties typically grow between 6 and 12 inches, making them ideal for gardeners with limited space.

To ensure your zinnias reach their full potential, plant them in a location that receives plenty of sunlight and give them regular water and fertilizer.

Should I 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.

Do Zinnias Need Full Sun?

Zinnias thrive when they have access to full sun. Ideally, they should receive six or more hours of direct sunlight daily.

However, some afternoon shade is acceptable in warm climates, although this could lead to fewer flowers and increased susceptibility to disease.

How Long do Zinnias Bloom?

Zinnias have a fairly long blooming period. They typically bloom in late spring and bloom until the first frost in fall.

How Long do Zinnias Take to Bloom?

Once zinnia seeds are sown directly into the garden, they bloom in about six to eight weeks.

Should You Soak Zinnia Seeds Before Planting?

Zinnia seeds do not require soaking before planting. They are warm-season annual flowers native to hot climates where the soil is warm, and the sun is hot. Once the seeds are sowed and watered, that is enough to get them to germinate quickly.

When Do You Plant Zinnias?

Zinnias can be planted in early spring after your area’s last expected frost date. In most regions of the United States, this is around Mid-March or early April.

How to Germinate Zinnia Seeds

Transplanting zinnias can be difficult, so it is recommended to plant them outdoors for the zinnia seeds to germinate to their fullest potential. The soil temperature should be at least 60 degrees to ensure the best results.

How Long Do Zinnia Seeds Take to Germinate?

Once planted 1/4 inch deep into the soil, you should see the first zinnia seedlings germinate and begin sprouting within four to seven days.

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With this easy guide on how to grow zinnias, I hope you plan to add them to your cut flower garden.

This post was updated with photos and text on February 1, 2022