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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My zinnias get eaten shortly after popping out of the ground. Would appreciate any suggestions. Thank you very much.
I live in a condo so do not have garden space. I planted zinias in plant boxes (plants are bunched together) They grew nice and tall but have not blossomed. What could be the reason?
Because the Zinnias are in smaller containers; you prob. have to add extra fertilizer; look for one "makes Blooms"; do not over use on roots; aw~
Humans are not the only beings attracted to these plants. Rabbits, deer, slugs, Japanese beetles, and European earwigs like them enough to eat all or part of them—especially in the night time. Try to block access to large critters and possibly the beetles, at least until the plants can achieve some size, with row cover secured at ground level. You might inhibit slugs with something “rough” they’d have to crawl over to get to the plants, like crushed egg shells or diatomaceous earth or other thick sand or gravel.
I had several packs of zinnia and would like to sow the seeds in May, in San Diego. Do you think it's the right time? Last year I bought some zinnia plants from the nursery and successfully transplanted to my containers. They had some disease on the leaves, which foods or chemicals I need to spray on them. Thanks so much.
Your timing should be fine but read the “Planting” advice above to be sure that everything else is fine, too. ;-)
Thank you for your advice and all shared comments here. My Zinnia Elegans have been blooming for few weeks, very beautiful.
They are packs of "California Giants" and "Northern Lights Blend" by Bontanic Interests Seeds company. I grew them in the containers and by the roses, don't know if it's fine for the roses (?)
I have been planting the seeds indoors and transplanting zinnias for the past several years since moving to North Carolina. I have also planted The seeds directly in the soil after the weather warms, to fill in the spaces where the transplants don't take as well. The ultimate germination and success rate does not seem to be much different for either procedure for me. I use bagged "garden soil" to amend the soil when transplanting the seedlings, and amend the soil with the same when planting from seed. I have added a slow dissolving fertilizer later in the season to aid growth and bloom. I plant varieties that are supposed to run from 18-36 inches tall, but always seem to get a number of plants over 6 feet tall, regardless of the variety or varieties used. Needles to say, staking is a necessity. Since these are grown on both sides of a rail fence, it can be used to tie up the plants, too.
OVER 6 FEET! Wow! Must be something in the water… This is great advice and you make it sound easy. Thanks for sharing!
Hi.
If i Plant Persian carpet zinnia right next to zahara zinnia, will they cross Pollinate?
