Besides sunflowers, my number one crop of summer and early fall cut flowers are zinnias, but the best way to plant them is in landscape fabric from seed. Floret will plant her zinnia seeds with a one-row seeder. For how many she is planting, that totally makes sense. For my large-scale gardening, I only need 1 mini-field of zinnias measuring 4’ x 24’. My first year, I fought with weeds with my zinnias. Consequently, my second year, I opted for landscape fabric with 9-inch spaced holes to keep the weeds at bay. It is by far my favorite way to plant and grow zinnias.
Zinnia Varieties
I love all sorts of different zinnia varieties. Some I bought from Rural King the previous season out of impulse. They were shades of coral and yellow, some of my favorite colors of flowers. I also grabbed a packet of scabiosa zinnias with the double blooms in multiple shades.
From MIGardener, I’m trying out salmon and yellow-colored zinnias. The yellow ones are named Isabellina and have a pastel hue. I also bought some candy-stripe zinnias that resemble a candy-cane with red and white stripes, but on the petals of a zinnia. I’ve grown those before years before for fun and it is just so neat to have flowers with contrasting hues on the same petal.
I’m still planting my white Polar Bear Zinnias from Baker Creek. However, over the last two years of growing these . . . They are not my favorite variety. I keep growing them to use up the seed. What I don’t like about them is for one they are advertised as double blooms with countless petals. The picture of them on Baker Creek’s website, they’re absolutely beautiful. When I’ve grown them, they look dirty, and over 90% of the blooms are singles.
https://www.rareseeds.com/store/vegetables/zinnias
My favorite place to buy zinnia seeds is from Johnny’s Select Seed. They offer packets of Benary’s Giant, Oklahoma, and the Queeny series. I love the huge blooms of the Benary’s Giant Zinnia. These are standard for large blooms. With loving the hues of yellow, peach, and coral, I bought golden yellow and salmon varieties, as well as the mix, which has such a range of colors- everything besides blue and green. The Oklahoma series are smaller blooms, but same length stems. I like these for supporting flowers.
I cannot say enough of the Queeny series. A previous season, I grew Queeny Red Lime. It was a stem so unique that customers loved it in bouquets. I had a few seeds left, which enough germinated to have a few plants of it. But, I also ordered another variety from this series.
https://www.johnnyseeds.com/flowers/zinnias/?start=12&sz=12
Old Zinnia Seeds
Seeds lose germination rates every year. Nevertheless, seeds can be dormant in the packets for years as well. I didn’t use up all my Benary’s Giant, Oklahoma, and Queeny Red Lime Zinnia seeds, so I started planting those this year. For the most part, they germinated. Not all of them came up, but enough for what I needed. Enough came up to justify trying to germinate last year’s seeds. Zinnia seeds have a shelf life of 3-6 years.
When to Plant Zinnias
WAIT until after your last frost to direct seed. Zinnias thrive in warmer temperatures. A night of cooler temperatures in the 30’s can kill them, especially young plants.
With all of my other spring planting I need to accomplish, I save planting zinnias until after I have my tomatoes plants, all my cool weather crops and flowers, and some of my warm-season flower transplants that may be root bound.
Why Use Landscape Fabric for Zinnias
Zinnias can be planted without landscape fabric. I know it can be expensive, or your space is smaller where you can manage the weeds. With the space that I have, I want to use something that manages the weeds.
Landscape Fabric 6’ wide will provide half a walkway on one side, 4’ of growing space, and half a walkway on the second side. The weeds will be suppressed between the plants, as well as in the rows. Weeds can still creep their way up the burnt holes with the zinnia plants. Nevertheless, weeding just around the plant will decrease the number of hours one would need to dedicate to weeding. For me with a large garden, using landscape fabric is SO worth it.
Another benefit is landscape fabric will keep the heat-loving zinnias warm. The black landscape fabric absorbs heat from the sun. Now, on hot, sunny days, if the zinnias were transplanted, it could fry the zinnia plants. From what I’ve seen with zinnias from seeds, they stay upright, never touching the plastic, and thus never wilting.
Landscape fabric will also retain moisture underneath. When we have a few days without rain- or weeks- this helps the zinnias needing water, as well as helping with soil health. On those consecutive sunny days, the soil would dry out and crack without the landscape fabric. Having moist soil will also make it easier for pulling any weeds.
How to Plant Zinnia Seeds for Cut Flowers
Lay down the landscape fabric. Use cement cap blocks or very large rocks to weigh down the fabric, or use landscape staples. Do NOT use small rocks in large groupings- this does not provide enough weight to keep the landscape fabric down from wind gusts.
If not completed yet, burn holes 9 to 12 inches apart. I chose 9-inch spacing for my zinnias, and I accomplished the spacing at a diagonal as well. Once the holes are burnt, they are there forever, so be diligent in your planning of your needs. Do NOT cut the landscape fabric- it will fray and unweave itself.
Open a packet of zinnia seeds into the palm of your hand. The seeds are a medium size, but are rather thin. Make sure to hold on to them if a wind gust happens to come through.
Use a finger to create a hole in the center of the burnt hole in the landscape fabric for the zinnias. Add two seeds at about ½” depth, approximately twice the size of the zinnia seed. Cover with surrounding soil. Repeat until all remaining holes have zinnia seeds added.
Thinning Zinnias
With planting two seeds, thinning will need to take place. One thinning option is to cut the off-centered or weaker zinnia seedlings. Just throw the secondary one away. For me, ehh, I hate throwing plants away. So, instead, what I do is I will gently pull that second seedling out of the ground. The other one needs to stay in the ground to not disturb its roots. Gently means gently.
If all the zinnia seeds germinated, then keep those seconds for other parts of the garden, whether flower beds, or maybe companion plants in the garden.
Sometimes, I have varieties where for the most part two seeds come up. Other varieties, whether from the seeds being older or maybe the seeds were not the best in the first place in terms of germination, the holes are empty. What I do in those cases, I will gently remove the secondary zinnia from one burnt hole to one with zero zinnia seedlings. Only do this when the plants are very small with just their first set of true leaves AND when the weather is overcast calling for rain. If you try to do this on a sunny day, transplanting zinnia seedlings may scorch them. They may wilt and flop over even on an overcast day, but 24 hours later they should all have perked back up and are doing well.
Zinnias as Cut Flowers
I’ve never bought zinnias as transplants. I know Lowe’s and Home Depot will sell them that way, but those varieties for the most part are bred to be short. Zinnias as a cut flower need long stems. The zinnias at big box stores may also be started from cuttings versus seeds. From my own experience growing from cuttings, I find that flowering plants from seeds gain so much more height than ones started from a cutting. From seed, it is a freshly new plant, not part of one that had to root itself. Zinnias from seeds are best.
As to whether you should start them direct seed or indoors, I find it easiest to just direct seed them. Grow light and greenhouse space is precious. They do well direct seeded. The direct seeded zinnias can even catch up to the transplanted ones.
Just note that zinnias are warm-season cut-and-come-again flowers. Meaning they love the hot weather, blooming in July, August, and warm Septembers. But also know that once they are cut, they will grow more stems. The more you cut, the more stems with zinnia blooms you will receive.
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