How To Successfully Grow Zinnias

There’s nothing quite like a row of gorgeous, lush zinnias growing all Summer long! These beautiful flowers grace my dinning room table every day. Zinnias are one of the easiest cut flowers to grow, and they will be one you turn to again and again. Here we’ll go over how to successfully grow Zinnias.

What you need to know:

Location
Soil
Germination and growth
Fertilizer
Maintenance
Potential problems

Before we get started on the how-to grow Zinnias, let’s take just a second to talk about the why-you-should.

Zinnias are a wonderful cut flower, and they make a wonderful addition to any bouquet.

Zinnias are non-toxic. What a relief that is for so many pet owners and farmers who want to grow lovely things, but find that many of the flowers we grow can harm our animals.

Zinnias, when planted in our vegetable gardens, draw in beneficial insects and pollinators. Their bright colors invite all the honeybees and butterflies to the location, and our vegetable plants welcome that!

Alrighty, let’s get started!

Location

Zinnias are a sun loving, heat loving flower. The more sunshine the better. Ideally these plants need at least 6-8 hours of sun a day.

When deciding where to plant, you’ll want to pick a spot that is full sun and has well drained soil. Planting in raised beds and pots is an option, however Zinnias have a large root system and do best if planted in the ground. That certainly doesn’t mean that they won’t do well in a pot! Just that, to really thrive, they need plenty of root space.

Soil

Zinnias are not picky, they grow very well in almost any soil condition. But if you want whats ideal for your plants, you need a well-drained soil. Zinnias can handle lack very well, but they appreciate a light, balanced fertilizer.

Germination and Growth

Zinnias can be started indoors a few weeks before your outside temps reach 70 degrees. Or you can direct sow outdoors after temps are consistently in the 70s and above.

To germinate, seeds need the temperature to be between 70-75 degrees or higher. They will start to peek out in 4-7 days. It’s very important to keep the soil consistently moist during this time.

Zinnias grow very fast! From germination to first flower is only about 2 months.

Once your plants have their first and second set of true leaves, you can pinch the tops to help the plant bush out more and produce more flowers. This isn’t a necessary step, but it certainly helps. This is how you do it…

Once your seedling has at least two sets of true leaves (the first set of round leaves when it germinates are not “true leaves”), you can pinch or cut the top of the plant, just below the top set of leaves. It will cause it to branch out to the sides, thus producing a bushier plant and more blooms.

Fertilizer

Zinnias don’t require a rich soil, but they appreciate a light fertilizer. When they are seedlings, a small application of fish emulsion is great, and then at around 4-5 weeks you can side dress with a basic 5-5-5 fertilizer for even bigger and healthier blooms.

Maintenance

Zinnias are cut and come again flowers. The more you cut, the more blooms they grow. It’s important to “deadhead” or cut blooms regularly, to encourage continual growth. When cutting your blooms, you want to snip under the first set of leaves on the stem, near the V. As shown below.

Zinnias don’t like their roots to stay wet, the soil needs to dry out a little between watering. I like to do a deep water every 2-3 days.

If you want to save seeds for the next year, allow a few blooms to stay on the plant and completely dry out. This you’ll want to do near the end of the growing season. Zinnias are not perennials, they don’t come back every year. However, they often reseed themselves. But it’s no guarantee, so I always make sure to save some seeds from my favorite plants.

Potential Problems

While Zinnias are very hardy plants, they can sometimes have a few issues.

If your Zinnias have leaf discoloration or limp leaves, that can be a sign of over-watering.

If your Zinnias have developed brown spots on their leaves, it can be a sign of nutrient imbalances, bacteria or fungal issues, or Foliar Nematodes (tiny worms).

In that case, I like to apply a spray mixture to my plants. I make it myself, it’s super easy! In a little bowl I mix 2 tablespoons of Neem Oil and 2 tablespoons of soap. Then I add it to a gallon of water in a sprayer.

The Neem Oil takes care of the bugs, and the soap (I use Sal Suds) takes care of the bacteria or fungal issues. Plus the soap is a carrier and aids in mixing the oil with the water.

Successfully growing Zinnias is as easy as that! And if you want to learn more, I have a post on How-To Grow Sunflowers that you can check out. Happy growing!