At the end of the growing season when your zinnia flowers are brown and dry, it’s time to save seeds for next year. Use these tips to know when to harvest and how to prepare your seeds for storage.
Also see 7 Best Tips For Growing Zinnias for lots of summer blooms.
Saving Zinnia Seeds
If you love zinnias and want to grow lots of them, the most economical way is to save seeds from your existing plants at the end of the growing season.
Harvested at the right time—with the right care, the seeds will be mature and stay viable for several years to come.
- Types of Zinnia Seeds
- Leave Your Best Flowers Alone
- When to Save Zinnia Seeds
- How to Save Zinnia Seeds
- How to Test Seeds
- How to Store Seeds
Types of Zinnia Seeds
Before you save seeds, it’s important to know the basic seed types, what they look like, and what to expect.
While there are open-pollinated and/or heirloom zinnia seeds in circulation, many of the zinnias we grow tend to be hybrids.
The advantage to growing hybrids is we get what they were bred for. This may be certain colors, shapes, sizes, disease-resistance, or any combination of these things.
The disadvantage is that only the first generation of seeds has the genetic traits that make it what it is. If you save seeds from hybrids, they usually do not come true to the parent. And for zinnias this means the flowers you grow from those saved seeds may be different than you are expecting. They may be similar, but perhaps not spot-on.
Whether this even matters depends on your preferences. Personally, I love all the interesting and unusual variations that zinnias have to offer and don’t mind the unexpected.
If you’re the same, start saving those seeds and see what the next sowing season brings.
Also, keep in mind that some seeds protected by plant patents, so you may want to check on this first.
What Do Zinnia Seeds Look Like?
Zinnia seeds are brown and often little arrowhead-shaped coats.
Some commercial zinnia seeds come coated, often with some mixture of clay, lime, and perlite, and appear completely different. The coating can help with handling and germination.
Leave Your Best Flowers Alone
The first step toward seed saving starts right in the middle of the growing season. If want seeds, we have to let the flowers die off and turn to seed. This means not deadheading to tidy things up or only deadheading some of them.
One important tips for best results is to mark your best flowers with ribbon. When it comes to plants, it’s the strongest, healthiest, and most vibrant ones that produces the best seed stock.
If you’re worried about the seeds blowing away, you can also place organza gift bags over the flowerheads. They allow air flow but will catch any seeds that fall from the flower at harvest time.
Let these beauties go right through their growth cycle and be ready to harvest seeds when the signs and signals tell you its time.
If the plant shows any sign of disease like powdery mildew, do not save any seeds from it.
When to Save Zinnia Seeds
We’re coming into seed harvesting time when the flowerhead is brown and faded in late summer or fall.
You need the seeds to mature first before harvesting.
Taken too early, the seeds will not be mature, which means they are not yet viable. Unripe seeds can be white in color. They turn brown as they mature.
But with zinnia you cannot see the seeds without pulling apart the flowerhead, which stops everything. So only sacrifice a flower to check inside if you have lots to spare.
Signs of seed maturity:
- It’s the end of the growing season.
- Most or all of the flower petals are brown and dry.
- The birds are starting to eat the seeds.
The ideal is to allow the mature flowerhead to remain on the plant for a week of warm sun to dry thoroughly. But the weather may have other plants.
If it’s mature but damp, you can bring it inside for drying.
How to Save Zinnia Seeds
When you think it’s time, try pulling a petal from the dry, brown flowerhead.
When the seeds are mature, the petal releases fairly easily and, attached to it, you’ll see the seed, in its little, brown, arrowhead-shaped coat. Each one of those “arrowheads” contains a seed.
When ready, cut off the flowerhead and bring it inside. Gently break open the flowerhead and spread out the petals and seeds over a screen, leaving them to fully dry.
The part to save is just those little arrowheads. Everything else can be discarded.
How to Test Seeds
Curious if your seeds will germinate? Even if you don’t want to grow zinnias now, you can still test some seeds for viability.
The Paper Towel Seed Test
- Moisten a paper towel so it is just moist, not soaking wet. If you squeeze it, it should not drip water.
- Spread out 10 seeds on half the paper towel.
- Fold over to cover so paper towel is touching seeds on all sides.
- Place everything flat in plastic food bag in a warm location away from direct sun.
- Leave bag open.
The ideal soil germination temperature for zinnias is 80-85°F (27-29°C).
Keep your seeds somewhere as close to this temperature range as possible without ever letting the paper towel dry out. Spritz with water daily as needed.
At optimum temperature, zinnias seeds can germinate in 3 to 5 days. At lower temperatures (in the 70sF) it takes 5 to 10 days.
If they sprout, pay attention to the numbers. If 7 out of 10 sprout, your germination rate is 70%.
If it’s seed sowing time, you can sow your sprouted test seeds.
How to Store Seeds
Use these tips for storing your seeds. Zinnia seeds remain viable for 3 to 5 years.
Optimum Seed Storage
The lower the temperature and moisture levels, the longer most seeds stay viable.
See this entire seed storage article for details.
Best temperature | 32-41°F (0-5°C)
Most fridges are in this range.
Also, room temperature (70°F/21°C or lower) is fine for short-term storage (1 year).
Store dry seeds and keep dry | Relative humidity below 50% | Keep away from light.
Paper Envelopes | In sealed jars with silica gel pack if moisture is an issue.
I hope this helped you get started with seed saving. Make yourself a reminder to sow those seeds in spring, either indoors or outdoors.
Also see 7 Best Tips for Growing Zinnias for more.
~Melissa the Empress of Dirt ♛