How to Direct Sow Zinnias in the Garden: 7 Seeding Tips
Zinnias are low maintenance and easy to grow, and the pollinators adore them! Join Florida gardener Melissa Strauss for some tips on growing zinnias from seeds this summer.
Contents
If you’re used to growing zinnias from nursery starts, you’re already familiar with how easily these flowers shine in the summer garden. They are drought and heat-tolerant, and few non-host plants can draw butterflies the way these do. What you might not know is how incredibly easy they are to grow from seeds.
Because they germinate quickly and don’t require soaking or stratification, zinnias need very little in the way of special treatment. As long as they have plenty of sunlight and don’t dry out too much, they stay happy and blooming from early summer until your first frost. Not to mention, they make wonderful cut flowers with their strong stems, large blooms, and significant vase life.
While their foliage can be attractive to a number of garden pests, they almost act as a trap crop amongst other plants. Very little affects their flowers; in many climates, these annuals will re-seed and return the next year. Here are some tips for direct sowing zinnia seeds for gorgeous flowers every year.
Buy From a Reputable Source
Most nurseries carry the usual garden variety, single-form zinnias. They are lovely, don’t get me wrong, but the selection of unique and beautiful cultivars available in seed form is astounding. Seeds are often the best way to go if you’re looking to grow some rarer and more unusual varieties.
Whenever I talk about buying from a reputable source, I feel I should give a disclaimer. I am one hundred percent in favor of ordering the fancy variety from a lesser-known source just to give it a try. As long as the price is right, there is no harm in trying. Just don’t let it get you down if they don’t have a stellar germination rate.
If you’re going to make a major purchase and invest in your garden, I highly recommend going with a tried and true retailer. At the very least, mix it up. This will help you avoid the major disappointment of poor performance across the board.
Here are some of my favorite varieties of zinnia seeds that I’ll direct sow in my cutting garden this year:
‘Polar Bear’
|
botanical name Zinnia elegans ‘Polar Bear’ |
|---|---|
|
sun requirements Full sun |
|
height 3’-4’ |
|
hardiness zones 2-11 |
‘Polar Bear’ is a pure white variety with a greenish center. The blooms are fully double and tend to stay that way throughout the season. I love this one because it works in any bouquet or arrangement. They are clean and classy but large and eye-catching at the same time.
‘Queeny Lime’ Series
|
|
botanical name Zinnia elegans ‘Queeny Lime’ |
|---|---|
|
|
sun requirements Full sun |
|
|
height 30”-40” |
|
|
hardiness zones 2-11 |
There is something special about this entire series that’s difficult to put a name to. There are several different colors, and each is a blend of a warm shade with green. The result is an earthy, rustic flower with an antique charm. ‘Queeny Lime Orange’ was a favorite last year, and this year, I’m planting ‘Queeny Lime Red’ and ‘Queeny Lime Blush.’
‘Peppermint Stick’
|
|
botanical name Zinnia elegans ‘Peppermint Stick’ |
|---|---|
|
|
sun requirements Full sun |
|
|
height 24”-36” |
|
|
hardiness zones 2-11 |
‘Peppermint Stick’ is a cultivar I happened upon through a mixed seed packet, and I’m obsessed. The petite semi-double blooms come in a range of shades, all flecked with red accents. In a bouquet, they make a fantastic surprise. I love to hide one or two among larger blooms as a special secret to anyone who looks closely enough!
‘Zinderella’
|
|
botanical name Zinnia elegans ‘Zinderella’ |
|---|---|
|
|
sun requirements Full sun |
|
|
height 25”-30” |
|
|
hardiness zones 2-11 |
This is the first year I am growing ‘Zinderella,’ and I am so excited! This series is seriously dramatic, with fluffy, cushioned blooms in a variety of forms and colors. It was a winner of the 2014 Fleuroselect Novelty Award.
Don’t Start Too Soon
Zinnias are native to Mexico and the Southwest and are not at all cold-tolerant. At the first sign of frost in the fall, they’re finished. Because they germinate so quickly, it’s imperative to wait until any chance of a frost has passed before you direct sow zinnia seeds. A frost will quickly wipe out your sprouts, and you’ll have to plant them all over again.
I know that as soon as we get those first warm days of spring, it’s hard to resist starting on your garden. This is one plant to hold off on, though. I recommend waiting until two weeks after your last frost date. Zinnias go from seed to bloom in right around two months. It’s worth waiting that extra week or two to get a strong start.
Direct Sow
There is no need to soak, stratify, or scarify your zinnia seeds before direct sowing. They are papery and delicate, with a thin outer coating. Under the right conditions, they pop up in as few as four days and strengthen quickly.
All of these factors make them ideal for directly sowing in the soil. You can save yourself the time and effort of starting them in trays and transplanting them. Your plants will be stronger and grow faster if you put them directly in the ground.
Thin Seedlings
When your sprouts reach about two inches tall, thin them out. Choose the biggest, healthiest seedlings to stay in the ground. You want about one plant every eight to 12 inches. Larger varieties may benefit from a bit more space.
When you do your thinning, be gentle and try to remove the entire root with the discards. If you can pull them out cleanly, you have more than one option in the next step.
Transplant vs. Discard
This might be a bit controversial, but I choose to replant my thinned zinnias rather than discard them. Sometimes, they take, and sometimes, they fail, but I find they are more often successful.
This is one of my favorite things about these annuals. They truly are tough and sturdy right from the beginning. As long as you get that tiny root system out intact, you can move them around to fill in where none sprouted or move them to a different location.
Give Them a Pinch
Pinching is a method of encouraging your plants to branch laterally. More lateral branching means more flowers. This only works with those that have a branching habit, which zinnias happen to have.
Wait until your seedlings are about six to eight inches tall. At this point, they should have several sets of true leaves, and you may be able to see some budding at the nodes. If you pinch too late, your branches could end up too high on the central stem, causing them to be top-heavy and flop over.
Using your fingers or a small set of clippers, pinch off or remove only the top set of true leaves. Remove them all the way down to the next set so that there is no leftover stem stump. This will make for a more attractive plant overall.
You can pinch again after your branches produce two sets of leaves. This will cause a bushier zinnia with even more blooms. However, it will slow down the bloom time. You’ll have to wait longer for results.
Cut or Deadhead Often
Deadheading is essential if you want to keep the flowers coming. Some plants are self-cleaning, meaning that they drop their own spent blooms, but zinnias are not. It’s important to remove the spent flowers to prevent them from going to seed early in the season.
These are some of my favorites for the cutting garden, so I rarely leave them until removal is necessary. After they open fully, I let the pollinators have them for a day or two and then cut the entire stem back to a bud. This causes them to branch, and two new blooms will grow in their place!
Zinnias have an exceptional vase life and outlast most others in the cutting garden. Their stiff stems and sturdy petals make them great for building the foundation of a floral arrangement.
One important factor to keep in mind when cutting is their hollow stems. Since the stems are hollow, it’s easy to crush them if you use your hands to pick them. I highly recommend using scissors or hand pruners. This way, you get a clean cut and don’t have to worry about floppy, broken stems.
