How to Grow Zinnias: A Step-by-Step Guide (2024)

Looking to add some beautiful color to your garden this year? Zinnias are the perfect flower for you! In this step-by-step guide, we will show you how to plant and care for these lovely flowers.

Why Grow Zinnias?

Zinnias are one of the easiest annuals to grow. Even beginner gardeners can sow the seeds to grow big beautiful blooms in their garden.

They bloom with ease from summer to frost and the more you cut them, the more they send out shoots and bloom.

They come in a wide range of shapes, colors, and sizes, so they are perfect for any garden. Let’s get started!

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Are Zinnia Annual or Perennial?

Zinnias are annual flowers, which means they only last one growing season.

You can plant them in the spring and they will bloom all summer long.

Will Zinnias come back from seed? That is a great question and in some climates, they will but in my garden (zone 8a) they do not reseed themselves.

Is there a Perennial Zinnia?

No. Not even in zone 9 – 10. I have seen it claimed that zinnias are perennial in those zones elsewhere on the internet but to be correct about it you must understand what a perennial is.

A perennial is a plant that comes back each year from the root. The same plant, not a seedling of said plant.

Zinnias are by nature an annual. An annual is a plant that germinates, grows, and goes to seed in one season. It does not come back from the original plant.

So don’t be fooled. There is no such thing as a perennial Zinnia. Sorry.

Zinnia Varieties

When choosing a zinnia variety, you will want to consider the size of the plant, the size of the flower, and the color.

Zinnias come in an array of sizes and colors, including white, yellow, pink, orange, red, purple, and various shades in between.

So you should be able to find one that suits your fancy. One of my favorite white zinnias is Polar Bear, they grow quickly and easily from seeds

To plant zinnias, you will need:

• – Zinnia seeds or plants
• – A sunny spot in your garden
• – Well-drained soil
• – A shovel or trowel, or favorite digging tool
• Consistent Irrigation
• Warm weather

When to Plant Zinnias

Zinnias are native to Mexico and like hot weather. Zinnias prefer warm soil to germinate and grow.

So don’t bother planting them out early thinking you will get a head start. Soil temperatures of 70 to 80 degrees are ideal and air temperatures above 70 degrees are the best.

Don’t be tempted to put them out early, they will just sulk.

You can start seeds indoors 4 to 6 weeks before your last frost date and some have great success with that but I have found that the ones I seed directly in the garden once the soil warms do just as well as those I have started indoors.

I will give it another test this year and let you know how it pans out.

If you are starting them indoors and don’t have an indoor seed starting set up then plant the seeds in small pots filled with well-drained potting mix.

Place the pots in a sunny spot and keep the soil moist.

Once the zinnia seedlings are big enough to handle and it is warm enough you can transplant them outside.

Can you Winter Sow Zinnias?

I have used the Winter sowing method to sow zinnias and I shared my results here. Technically, I would call it Spring sowing in milk jugs but it is the same technique as winter sowing just later in the season.

Where to Plant Zinnias

Find a sunny spot in your garden for your zinnias. Zinnias need at least six hours of sunlight each day to bloom well.

Once you have found the perfect spot, plant the seeds, I like growing in drifts instead of rows.

Drifts are patches laid out in no particular order just give space for each zinnia to fill in and not be crowded.

Zinnias need fertile, well-drained soil, so be sure to loosen the soil and add some organic matter (compost) if needed.

When planting zinnias outside, the first thing is to read the seed packet.

Different-sized plants need different plant spacing.

To be honest, I fudge on the recommendations and do my own thing, but I keep them in mind.

The instructions may say to sow 3 seeds every 8 to 12 inches and then thin them once they have germinated.

I will sow one seed instead, then reseed a week or so later if one does not germinate.

That way I use fewer seeds and I don’t have to pull out any that are too close together.

Zinnia seedlings are said to not like having their roots disturbed so transplanting success can be hit or miss. I do it all the time and have had no problem.

Be sure to keep an eye on the soil and water as needed.

Zinnia Care

Keep the soil moist but not wet and water the ground at the base of the plants.

Zinnias can be susceptible to powdery mildew. Some say you can use a weekly spray of 50 percent milk and 50 percent water to help with the mildew but I don’t know how that can affect beneficial insects.

Plant them with enough space for good air circulation and if you live in a humid environment try to find varieties that are mildew resistant.

I like using soaker hoses or drip irrigation for watering.

Not only does it save water but it keeps the moisture at the base of the plants where it does the best.

Mulching will also help to keep moisture in the soil and if it is a bark mulch it can help prevent the splashing of soil up onto the foliage.

Keep Zinnias Blooming

This is optional: Once your Zinnia seedlings have 4 sets of leaves or more, pinch them back to just above a leaf set.

This encourages branching which leads to more blooms.

Deadheading or cutting for bouquets will force the plant not to set seed and thus produce more flowers.

You can collect the zinnia seed at the end of the season of some varieties of Zinnias to sow again next year but some are also hybrids that will not come true.

One of note is the Queen Lime series, they are hybrids and if you save seeds and sow them the following year you will not get the same flowers.

Do a bit of research on the ones you are growing to find out if saving the seed of your Zinnias will result in the same flowers or if you are adventurous just be content with what you get.

Now that your zinnias are planted, it’s time to sit back and enjoy the show!

These beautiful flowers will bloom all summer long.

With a little care, you will have a beautiful zinnia garden that you can enjoy all season long!

Do you have any tips for growing zinnias?