How to Grow: Zinnia

Zinnias—When we think about a cut flower garden, we picture rows and rows of happy zinnias slightly blowing in the wind. Their bright, happy flowers, with all kinds of colors, textures, sizes, and shapes, can be bouquets on their own.

Many of us remember zinnias growing in our Grandparent’s gardens or our own family gardens.

Zinnias are super versatile and come in various colors and sizes. In blushes, whites, and greens or bold and bright, they can be used for wedding work or as a statement piece on your table.

Zinnias are among the easiest cut flowers to grow and are great for beginners. They are reliable and prolific—just what we need to be rock stars in our garden.

How to Grow:

When to Plant:

Zinnias love hot weather, which in turn means they resent being cold. As tempting as it is to plant them out early, your zinnias will not like that. They will sulk and throw a fit, delaying their bloom time. Here in West Michigan, Zone 6a, I usually wait until the end of May to plant. Some years, I even waited until the beginning of June.

Zinnias can be started indoors two to four weeks before planting or directly sown into the garden two weeks after the last frost date. Zinnias should be transplanted into the garden when they are three to five inches tall.

Where to Plant:

The sunniest, hottest part of your garden. Zinnias need at least 8 hours of sun. If possible, they love the hot, cooking afternoon sun.

Plant Spacing:

I plant my zinnia’s 9 inches apart. If you have the room, you can space them up to 12 inches apart. This can help airflow, especially if you suffer from powdering mildew yearly.

To Pinch or Not to Pinch:

The secret to those beautiful long, long-stemmed zinnia is pinching.

Pinching is a term used to describe the cutting or removing the top of the plant, right above a set of leaves that forces the plant to branch. Instead of getting one thick stem up the middle of the plant, it will produce three to four stems.

When plants are about 18 inches tall, snip out the center stem or flower bud. I know it’s hard, but you can do it.

Flower Support:

Is flower support necessary? No, but I do recommend it. We get some good thunderstorms here in West Michigan, and it would be really sad if your sweet zinnia patch was flattened by some powerful wind.

The one expectation of this would be if you live in a very secluded or covered area. Fenced neighborhoods are usually safe from the terrible winds. So, survey your growing space and decide for yourself.

I use horticulture netting and stakes. Install as soon as possible after planting. Zinnia’s grow fast, and you don’t want to miss this opportunity.

Pests and Diseases:

Pests: Cucumber Beetles and Japanese Beetles. These are the main threats to zinnias. They make me crazy! The healthier your soil, the healthier your plant will be. Even so, these insects can decimate your crop.

I pick Japanese Beetles off each morning. I take a cup or bucket of soapy water and know them right into it. It’s not fun.

Cucumber beetles - I squish them every chance I get. Some years, they are really bad.

Insect sprays also help eliminate insect damage, but you must be consistent.

Harvesting and Conditioning Tips:

Harvesting:

First, ensure your buckets and cutters are clean and have fresh, clean water.

Make the cut at the base of the stem, right above the bottom, two or three leaf sets.

Harvest when the blooms are fully open. Look for the little yellow flowers (stamens) to begin to develop in the center.

You want to use the “wiggle” test. The stem below the flower should be rigid, and the flower head is not floppy. Grab the stem and give it a wiggle.

Conditioning:

Zinnias are considered dirty flowers because they make the water in your vase dirty. Using a drop of bleach or a chlorine tablet in your water bucket helps stop the spread of bacteria, which shortens the life of your zinnias.

Let your zinnias rest for at least four hours following harvest.

Use fresh flower food in the vase when arranging.

Favorite Varieties:

Benary's Giant Series: These are the best and most widely grown cut flowers. They have nice large flower heads, often doubled and full. They come in many colors and have nice, strong stems.

Oklahoma series: Think of these zinnias as the younger sister to the Benary’s Giant series. They have smaller blooms with a similar look. They are a great filler and look good combined with almost anything.

Queen Series: No other flowers come in these unique colors. They are gorgeous and soft. They are smaller than the Benary’s Giant Series but bigger than the Oklahoma Series.

If you grew only these three zinnia varieties, you could cut buckets of flowers and create fun and beautiful bouquets.

There are a lot of other varieties to grow as well. Don’t just stop at these three. Grab a seed pack or two and see what happens!