Planting, Growing, and Caring for Zinnia Flowers
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Planting
Choosing a location that gets full sun (6 to 8 hours of sunlight per day) is essential to getting plentiful blooms throughout the season. Additionally, a site that offers good air circulation will help to prevent foliar diseases such as powdery mildew later in the season.
Zinnias are able to adapt to most soil conditions, but the ideal soil will be rich in organic matter and well-draining. Soil pH should ideally be between 5.5 and 7.5. If soil is amended with compost (humus), the flowers will grow more quickly. Learn more about soil amendments and preparing soil for planting.
When to Plant Zinnias
- It’s recommended that you grow zinnia from seed right in the garden bed, as they do not like to be transplanted. From seed, they will grow very quickly in the right conditions.
- Note: Zinnias can be started from seed indoors if you prefer—just transplant them while they’re young and do so carefully.
- Zinnias are sensitive to frost, so do not seed until the last frost has passed in your area. See your local frost dates.
- Zinnias will grow in a minimum daytime temperature of about 60°F (16°C), though a range of 74°–84°F (23°–28°C) is preferred.
- Sow a round of seeds every week or so for several weeks to extend the flowering period.
How to Plant Zinnias
- Space plants 4 to 24 inches apart, depending on variety. (Many common varieties are planted 6 inches apart within the row and 2 feet in between rows.) See the back of the seed packet for variety-specific advice.
- Sow zinnia seeds only about 1/4 inch deep.
- Most zinnia varieties grow tall and need staking to prevent their heavy stems from lying on the ground. A few weeks after planting, stake close to the plant stem. Take care not to injure roots.
- Gardeners who grow many zinnias (especially for cutting) stretch pea netting over young plants between stakes and bamboo canes; the zinnia heads are then supported gently by the almost invisible netting.
- Get a full-size flower on a compact plant with cultivars of the Dreamland Series. Dwarf and compact, these zinnias have fully double flower heads, up to 4 inches across in a wide color range; stems are 8–12 inches tall.
- The Thumbelina Series cultivars are dwarf and spreading, with single or semidouble, weather-resistant flower heads in many colors. Their petals are 1-1/4 inch across and stems grow up to 6 inches long.
- The State Fair Series are one of the biggest and tallest of them all, with large, double flower heads that are 3 inches across. Stems grow to 30 inches tall.
Harvesting
- Zinnias generally take 60 to 70 days from seed to flower (though it depends on conditions and variety). They work great in a flower bouquet!
Saving Zinnia Seeds
To save zinnia seeds for replanting, simply collect a few blossoms that are at least halfway brown and let them dry in a paper bag until the seeds shatter.
- Find the dark, pointed seeds at the bases of outer petals, with more along the center of the flower.
- Dry on a paper towel until hard and almost crisp.
- Store in a paper bag in a dark, dry location until you plant again in the spring.
Catherine Boeckmann
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Hi, I'm doing a project with Zinnias and having a plant sale at my school. I was wondering how many times should they be fertilized?
And what type of fertilizer do they use?
Zinnias don’t need a lot of care. When they’re seedlings (about 4 inches tall), you could apply 5-10-5 liquid fertilizer. And perhaps apply again mid season. However, many folks don’t use fertilizer at all.
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HI, I planted zinnias out in my front garden & even though they were growing magnificently & as I watered & fed them on a regular basis & they were getting the full light of the daily sun, somehow the one plant had gotten all twisted & bent & started snapping off in different areas. Then in the end, the whole plant gave way & fell to one side, is there any reason as to why this happened & how do I fix it?
How heavy do zinnia plants get? I'm doing a school project and am trying to figure out the weight of zinnia's at different stages of growth.
Thanks!
Will Zinnia seeds germinate in a completely dark growth chamber, that provides optimal temperatures, providing one removes them as soon as they sproat?
They actually need light to germinate. What I do is; take a paper towel, sprinkle my seeds onto it, moisten the paper tower and wring it out, place in a zip-loc bag, leave a tiny air opening in seal and I usually have my seeds germinated by morning. It's wonderful and so fast. I then take the sprouted seeds and place them in soil and they perk up the next day. This is the fastest way to germinate them in my experience. Just make sure they get a little light for germination. Good luck!
It's my first time planting. How many seeds are allowed to put in the hole when planting.
Hi Ria,
Generally, 1 or 2 seeds are placed in each hole, between 4 and 24 inches apart, depending on the variety. The back of the seed package can explain more specifics for your variety. However, zinnias take about two months to grow from seed to flower, so depending on where you live there may be a frost before your plants can fully bloom. If your region experiences a cold winter, you can plant your zinnias in pots for indoor growing. We hope this helps!
I sowed a large bed of zinnias, thinning them as they grew, but they developed purple spots on the leaves and are even dead looking near the soil although they are still flowering profusely. I made the mistake of watering them with a sprinkler when they got dry as it's a large area to cover. I have seen gorgeous zinnias in other gardens that look like they're supposed to. I want to do a bed again next year and my husband is going to put in a drip system to irrigate and also amend the soil better. Any advice for better results would be appreciated. Also, can I use the seeds from this year or will I just be perpetuating the same problems?
What does "deadhead" mean?
