How to Grow Gorgeous Zinnias (For Floral Design)
How to Grow Gorgeous Zinnias (For Floral Design)
I don’t know about you, but one of the first flowers I ever grew from seed was a zinnia.
It was a patch of State Fair zinnias - purchased from a cheap ten cent packet with the most horrible photograph on it - and I was surprised by how easily they grew. In the hot and humid summer, the zinnias got huge and bloomed effortlessly, filling the garden and landscape with their hot and bold colors.
There’s definitely something about the brightly colored blooms that are absolutely stunning. They are a wonderful flower that I am happy we are able to grow consistently, no matter where we live. And they are so easy to grow - it’s a flower that I think we’ll continue to grow every single year.
Zinnias are the workhorses of most flower farms, producing endless, abundant bucketfuls of big fluffy colorful blooms all season long for a minimal amount of work. The more and more I grow flowers, the more I enjoy growing zinnias for their ease of growing habit and their performance in the garden and when cut into an arrangement.
Selecting your Variety
There are a wide variety of zinnias available - seemingly for every intent and purpose.
You have big, giant zinnias like the ‘Benary Giant’ series that can get a good 3-4” across and are perfect double gorgeous blooms in a wide variety of colors. The perfect zinnias for cutting and using in arrangements, they are almost like Gerbera daisies in appearance - fully double in most cases, with those same fluffy outer petals that are almost like a tutu in appearance.
On the other hand, you also have the ‘Queen’ series. As opposed to the bright and bold colors of the ‘Benary Giant’ series, the ‘Queen’ series are a lesson in subtlety. Coming in shades of muted dusty rose combined with the delicate light green of viburnum and hydrangea petals, these zinnias are unlike the ones that you see in home gardens and in landscapes - they have a beautiful antiqued, heirloom look to them. They also have a great form, creating an almost spherical, perfect shape in some cases.
There are also smaller zinnias in case you don’t want the gigantic blooms as well. Of particular note are the ‘Oklahoma’ series of zinnias - small double blooms that bloom prolifically and fully, looking almost like little macarons on top of the stems, coming in all the colors of the zinnia rainbow.
There are also the ‘Zinderella’ series, known for their poofy scabiosa-flowered forms. After growing these for several years, we seldom get the cupcake-shaped scabiosa flowering forms - less than 5% of all the plants we grow have any sort of double nature, instead usually ending up as singles - but are gorgeous nonetheless with the pale light lavender of Zinderella lilac and pale peach of Zinderella peach respectively that add a certain elegance and lightness to any arrangement.
Interestingly enough, the ‘Cresto’ series of zinnias are also rumored to be scabiosa-flowering, and are supposedly at a higher rate of 75% scabiosa/cupcake form. We’ll be growing this year to see if it’s true or not.
Lastly, there are the zinnias of the haageana group. Short but prolific, these zinnias are usually more suited for the front of the border or as bedding plants, but if pinched hard enough and grown out with plenty of water and fertilizer, their flowers can get tall enough to be used for arrangements.
I’m particularly in love with the ‘Jazzy’ mix, a warm-toned haageana group zinnia with plenty of doubles and bicolors in diminutive sizes that work well mixing into bouquets and arrangements all season long.
Zinnias are relatively quick to bloom from seed in around 75 days or so which is pretty quick for such a gorgeous flower. They sprout really quickly and easily from seed, which means that you’re going to have a quick growing plant that will get large very quickly.
Given that zinnias are natives of Mexico, they like heat - they’re one of the prototypical summer hot annuals that loves the weather of July and August. Accordingly, when you start your zinnias they need heat to germinate. You can use a heat mat if you’re starting zinnias early in the season, or you can also direct sow them when the ground is warm enough (my favorite way of doing so).
The “fancy” zinnias that I particularly want to have the big fluffy double forms - the Benary Giants, the Queen series and the Zinderella series - I will actually start early to ensure they get a little bit of cooler weather when first growing, as it helps them achieve the lovely double flowering forms at a higher rate.
Zinnia seeds are easy to handle because they are so large. The size of sunflower seeds, they are perfect for grasping between your thumb and your forefinger and planting into the soil. It’s one of the reasons why they’re one of the few plants that I direct sow.
Remember, you’re going to want to have heat to trigger germination of zinnia seeds - whether through a heat mat or the rays of the sun or the residual heat of ground warmed by the sun. I personally like to cover my zinnia seeds with a thin layer of dirt or soil to keep them moist during the germination process, but you can also surface sow them as well so long as you keep them moist and warm.
If you’re planting into trays or soil blocks, make sure that you keep an eye on them and plant them out quickly. Zinnias grow very quickly and will outgrow little cells or soil blocks rapidly, which can cause them to become rootbound. You don’t want that - we usually transplant them out when they get their first pair of true leaves.
4. Growing Out
The ideal environment for zinnias is around 70-80 F during the day and plenty of moisture and air circulation - but since most of us don’t live in the Pacific Northwest near the ocean, we can still grow great zinnias as they can tolerate a very wide range of conditions.
Zinnias, once they get going, require very little care. They handle drought and sun and heat and even rain pretty well. So long as they have a good source of nutrients and a relatively regular source of water, they will grow into big bushy plants sometimes up to 3’ wide and as tall.
We don’t use netting given our relatively dry environment, but you may want to use netting if your zinnias get too tall and succulent. Personally, we prefer to just plant our zinnias close enough to where they support each other.
Zinnias are truly a wonderful flower for cutting because they are one of those cut-and-come-again flowers. So long as you keep cutting flowers from the plant, it will continue to produce flowers for you all season long.
The first stem is the biggest and most glorious of all the flowers you will receive - sometimes with the stem being almost half an inch thick - and it’s important to cut that first stem all the way to the base of the plant.
This is in essence pinching the zinnia plant so that it will produce numerous side shoots. It may sound counterintuitive - and may be absolutely painful to do so, especially when you’ve waited so long for the first flower to bloom - but I assure you that it’s very important to do so in order to have your zinnias continue to produce.
Don’t make the mistake of letting the flowers stay on your zinnia plants for too long. First of all, flowers that stay on the plant start looking old and contribute to a patch of zinnias looking ratty or outdated. Secondly, if you leave old flowers on a zinnia, it will start producing seed - which means that it will put all its energy into producing seeds and stop pushing out flowers for you to cut.
Zinnias are best harvested when their outermost petals are open or almost open, but the interiors are still curled tightly. The best way to check is what we call the stem test - grab the zinnia by the stem and jiggle it back and forth. If the stem is very firm and the top head of the flower doesn’t move too much, the zinnia is ready to harvest. If the stem flops back and forth causing the zinnia’s head to flail around like a muppet character, then it’s not quite ready to harvest.
Cut zinnias into cool and fresh water. It’s important that the water is very clean - zinnias are notorious for being a “dirty” flower, soiling their water in a very short period of time, so the cleaner the better. We know of many flower farmers who use chlorine tablets for zinnias to keep their water sparkling clean and fresh.
Zinnias are a great supporting or secondary flower, both for their complimentary colors as well as their disc-like form that echoes the shape and pattern of other focal flowers.
That being said, depending on the size and type of your arrangement, the bigger and more impressive blooms like a Benary Giant or a Senora can be used as a focal flower itself.
Generally we use the larger zinnias like the Queen series or the Benary Giants as supporting flowers, and then use the smaller zinnias like Jazzy Mix and Oklahomas and Zinderellas as secondary supporting flowers. The mix of similar flowers of different scales and types helps to again create rhythm and pattern within an arrangement, which really helps to pull arrangements together and make them seem very cohesive.
It’s important to use fresh zinnias in your arrangements. Although some people have reported keeping zinnias for up to seven days, we find they usually don’t last for us much longer than three to four. When cutting for florists to use in design, we generally try to cut them the night before delivery to ensure they get the freshest zinnias possible.
I hope that if you’ve been on the fence about growing zinnias - whether because you thought they were too simple, only came in garish bright colors, or weren’t worthy of your attention - you’ll try growing some this year. There’s really no other flower that can give you so much beauty and productivity that is grown with such ease, and one that is happy to perform in drought and poor soil as well as it does it humid and rich soil as well.