Heirloom

Oklahoma Scarlet

Zinnia elegans

Photo: Tergiversant (talk) · Wikimedia Commons · (CC BY-SA 3.0)

Prolific 1 1/2-2 1/2" double and semidouble petite, yet sturdy, scarlet red blooms. Excellent, reliable accent flowers for market bouquets, wedding flowers, and event work. Cut-and-come-again flower, yielding multiple cuts over the season.

Harvest

75-90d

Days to harvest

📅

Sun

Full sun

☀️

Zones

2–11

USDA hardiness

🗺️

Height

0-3 feet

📏

Planting Timeline

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Start Indoors

Transplant

Direct Sow

Start Indoors

Transplant

Direct Sow

Showing dates for Oklahoma Scarlet in USDA Zone 7

All Zone 7 flower →

Zone Map

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Oklahoma Scarlet · Zones 2–11

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

Spacing9-12 inches

SoilFertile, well-drained loam, pH 6.0-7.0

WaterModerate — about 1 inch per week, watered at the base

SeasonWarm season annual

Size1 1/2-2 1/2"

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
Zone 1	May – June	July – August	July – September	—
Zone 2	April – May	June – July	June – August	—
Zone 11	January – January	January – February	January – March	—
Zone 12	January – January	January – February	January – March	—
Zone 13	January – January	January – February	January – March	—
Zone 3	April – May	June – July	June – August	—
Zone 4	March – April	June – June	June – July	—
Zone 5	March – April	May – June	May – July	—
Zone 6	March – April	May – June	May – July	—
Zone 7	February – March	April – May	April – June	—
Zone 8	February – March	April – May	April – June	—
Zone 9	January – February	March – April	March – May	—
Zone 10	January – January	February – March	February – April	—

Succession Planting

Oklahoma Scarlet keeps blooming as long as you deadhead it regularly, so a single planting will carry you through most of the warm season. That said, if you want continuous flushes of fresh, full-sized blooms rather than relying on one planting to sustain itself, direct sow every 3 weeks from your last frost date through early summer — in zone 7, that's roughly April 1 through June 15. Stop sowing once daytime highs are reliably above 90°F; seeds germinate fine in heat, but seedlings started that late often get cut short by first frost before they hit peak bloom at 75 to 90 days.

If you're growing for cut flowers specifically, that 3-week cadence makes a real difference — you get distinct waves of stems rather than a single mid-summer glut. Pinch transplants or seedlings at 8 to 12 inches tall to encourage branching; plants left unpinched tend to throw one strong central stem and then slow down considerably.

Complete Growing Guide

Oklahoma Scarlet is one of the easiest cut flowers you can grow, but a few details separate a decent patch from a truly productive one. Start by choosing a site with at least 6–8 hours of direct sun and good airflow — zinnias are prone to powdery mildew, and crowded, shaded plantings will mildew by midsummer no matter what variety you grow.

Work 2–3 inches of finished compost into the bed before planting and add a balanced organic fertilizer (something like 5-5-5) at the rate listed on the bag. Zinnias prefer fertile, well-drained soil with a pH around 6.0–7.0. Heavy clay should be amended with compost; sandy soils benefit from added organic matter to hold moisture.

You can direct sow Oklahoma Scarlet after your last frost date once soil temperatures reach 70°F, or start seeds indoors 4–6 weeks before transplanting. Indoor starts give you a 2–3 week head start, which is valuable in cooler zones (3–6). Sow seeds ¼ inch deep; they germinate in 5–10 days at warm temperatures. Don't start them too early — zinnias resent being root-bound and sulk for weeks if transplanted late.

Space plants 9–12 inches apart for cut-flower production. This tighter-than-recommended spacing forces longer, straighter stems and discourages overly bushy growth. For market growers, a single layer of horizontal netting (Hortonova) installed at 12 inches high will keep stems straight through summer storms. Home gardeners can usually skip staking thanks to Oklahoma Scarlet's sturdy habit.

Pinch your plants when they reach 8–12 inches tall by snipping out the top 3–4 inches above a set of leaves. This single step is the most-skipped trick in zinnia growing — it triples your stem count and dramatically improves stem length on later harvests. Pinched plants branch from the base and produce dozens of usable cut stems instead of one central flower.

Water deeply once a week, aiming for about an inch, and water at the base of the plant rather than overhead to keep foliage dry. Drip irrigation or soaker hoses are ideal. Side-dress with compost or a light dose of liquid fish emulsion every 3–4 weeks during peak bloom to keep production high.

Common mistakes to avoid: planting too early in cold soil (seeds rot), overhead watering (mildew), skipping the pinch (short stems), and harvesting too soon (floppy stems that won't hold up in a vase). In zones 8–10, a second succession sown in early July will give you fresh, mildew-free plants for fall harvest when your spring planting starts to fade. Deadhead or harvest religiously — every spent bloom left on the plant signals it to slow production.

Harvesting

Oklahoma Scarlet is a cut-and-come-again flower, and harvest technique directly affects how many stems you get over the season. The single most important rule: cut deep. Reach 12–18 inches down into the plant and snip just above a leaf node, even if you're sacrificing a few smaller buds. Shallow cuts produce short, weak side stems; deep cuts force vigorous new growth from the base.

Use the "wiggle test" to judge readiness — gently grasp the stem about 8 inches below the bloom and give it a shake. If the stem is stiff and the flower head stays upright, it's ready. If the stem bends or the flower flops, leave it another day or two. Picked too early, zinnia stems will never firm up in the vase.

Harvest in the cool of early morning when stems are fully hydrated, and plunge them immediately into clean, cool water. Strip all foliage that would sit below the waterline. Cut every 2–3 days at peak season; the more aggressively you harvest, the more the plant produces.

Storage & Preservation

Once harvested, condition Oklahoma Scarlet stems in clean water with floral preservative for at least 2–3 hours in a cool, dark location before arranging. Properly cut and conditioned stems hold 7–10 days in the vase — exceptional for a zinnia. Store at 38–40°F if you have a flower cooler, but unlike many cut flowers, zinnias are chill-sensitive and can be damaged below 35°F, so don't use a regular refrigerator for long-term storage.

For preservation, Oklahoma Scarlet's smaller, denser blooms dry beautifully using silica gel, retaining their scarlet color far better than air-drying (which fades them to dusty maroon). Pressing also works well for the semidouble blooms — flatten between blotter paper under heavy books for 2–3 weeks for use in resin jewelry, cards, or framed botanical art.

History & Origin

Oklahoma Scarlet is part of the Oklahoma series of zinnias (Zinnia elegans), a cut-flower series developed specifically to address a gap in the market: florists and bouquet makers wanted a smaller-bloomed, more refined zinnia than the popular Benary's Giant series, with the same disease tolerance and long stems. The Oklahoma series — which also includes Salmon, Pink, Ivory, Carmine, and Formula Mix — was bred to produce 1½–2½ inch double and semidouble flowers on long, wiry stems ideal for mixed bouquet work.

Like all garden zinnias, Oklahoma Scarlet traces its ancestry to Zinnia elegans, a wildflower native to the grasslands of Mexico. Spanish botanists sent seeds to Europe in the 18th century, where the genus was named for German botanist Johann Gottfried Zinn. Modern cut-flower zinnia breeding accelerated in the late 20th century as the specialty cut-flower industry grew, and the Oklahoma series has become a backbone variety on small flower farms across North America for its productivity, color saturation, and excellent vase life.

Advantages

+Exceptional vase life of 7–10 days, longer than most zinnia varieties
+Smaller bloom size makes it ideal for mixed bouquets where Benary's Giants would dominate
+True scarlet red color holds saturation in heat without fading to pink or coral
+Sturdy, wiry stems rarely require staking even in summer storms
+Cut-and-come-again habit produces dozens of stems per plant over the season
+Easy from direct-sown seed — beginner friendly with high success rate
+Heat and humidity tolerant, performing well in southern summers

Considerations

-Susceptible to powdery mildew in late summer, especially with overhead watering or poor airflow
-Requires aggressive pinching and deep harvesting to reach full productivity — casual gardeners often get short stems
-Not frost tolerant; a single light frost ends the season
-Can attract Japanese beetles, which target the open blooms
-Smaller bloom size means it works as an accent flower, not a focal flower

Companion Plants

Marigolds and nasturtiums are the most practical companions here. French marigold types like 'Petite Gold' release thiophene compounds from their roots that suppress root-knot nematodes in the surrounding soil, and their scent is thought to confuse aphids scouting for nearby vegetable crops. Nasturtiums pull double duty — they draw aphids away from more valuable plants and attract predatory insects like lacewings. Neither one competes hard with Oklahoma Scarlet's root system, which stays shallow given the plant tops out around 3 feet.

Sweet alyssum and catmint earn their spots by pulling in parasitic wasps and hoverflies — both of which prey on soft-bodied pests like aphids and thrips. Plant them as a low border 6 to 8 inches out from your zinnia rows and they act as a landing pad for those predators without shading anything out. Cosmos is a looser fit; fine nearby, but at 4 to 6 feet it can lean into shorter zinnias if you're not watching placement.

Black walnut (Juglans nigra) is the one to keep well off the list — juglone, the compound it releases from roots and decomposing hulls, is toxic to a wide range of ornamentals within the drip zone, and zinnias aren't tolerant of it. Eucalyptus causes similar problems through allelopathic oils in both its roots and dropped leaf litter; the damage there tends to show up as stunted, off-color seedlings that never really get going. Sunflowers aren't chemically problematic the same way, but they're aggressive enough for light that anything planted closer than 18 inches tends to come up short.

Plant Together

Marigolds

Repel nematodes and aphids while attracting beneficial insects

Nasturtiums

Act as trap crops for aphids and cucumber beetles, protecting nearby plants

Sweet Alyssum

Attracts beneficial insects like lacewings and parasitic wasps

Zinnias

Attract pollinators and beneficial predatory insects while providing color contrast

Cosmos

Attract beneficial insects and provide structural support without competing for nutrients

Lavender

Repels pests like moths and fleas while attracting pollinators

Catmint

Deters aphids, ants, and rodents while attracting beneficial pollinators

Petunias

Repel aphids, tomato hornworms, and other garden pests

Keep Apart

Black Walnut Trees

Release juglone toxin that inhibits growth and can kill sensitive flowering plants

Sunflowers

Produce allelopathic compounds that can stunt growth of nearby smaller flowers

Eucalyptus

Releases allelopathic oils that inhibit seed germination and plant growth

Troubleshooting Oklahoma Scarlet

What you'll see, why it happens, and what to do about it.

White powdery coating on upper leaf surfaces, usually showing up mid-summer once plants are mature

Likely Causes

Powdery mildew (Erysiphe cichoracearum) — a fungal disease that thrives in warm days, cool nights, and poor airflow
Crowded spacing under 9 inches that traps humidity between plants

What to Do

1.Remove and trash the worst-affected leaves — don't compost them
2.Thin or cut back neighboring plants to open up airflow around the stems
3.Spray with a diluted potassium bicarbonate solution (1 tablespoon per gallon of water) every 7 days until new growth looks clean

Seedlings collapse at the soil line within the first 2 weeks after germination

Likely Causes

Damping off — typically Pythium or Rhizoctonia fungi, almost always triggered by overwatering or poorly draining seed-starting mix
Sowing too early into cold, wet soil below 60°F

What to Do

1.Don't water again until the top half-inch of the mix is dry
2.If starting indoors, use a fresh sterile seed-starting mix — not garden soil or old potting mix from last season
3.For direct sow, wait until soil temps are consistently at or above 65°F

Ragged holes chewed in petals and flower buds, sometimes whole buds disappearing overnight

Likely Causes

Japanese beetles (Popillia japonica) — they're particularly drawn to open-faced flowers like zinnias in mid-summer
Caterpillars (various Lepidoptera larvae), especially if damage appears on both petals and nearby leaves

What to Do

1.Hand-pick Japanese beetles in the morning when they're sluggish and drop them into a bucket of soapy water
2.Check the undersides of leaves for caterpillar egg masses and crush them
3.Apply Bacillus thuringiensis (Bt) spray to foliage if caterpillar pressure is heavy — it won't affect beetles, so identify which pest you have first

Frequently Asked Questions

How long does Oklahoma Scarlet zinnia take to grow?▼

Oklahoma Scarlet takes 75–90 days from sowing to first harvest. Seeds germinate in 5–10 days in warm soil, and plants typically begin blooming about 10–12 weeks after sowing. Once it starts producing, expect continuous blooms for 8–12 weeks until your first frost, especially if you harvest or deadhead consistently. For earlier blooms, start seeds indoors 4–6 weeks before your last frost date and transplant after the soil warms to 65–70°F.

Is Oklahoma Scarlet good for beginners?▼

Yes — Oklahoma Scarlet is one of the most beginner-friendly cut flowers available. Zinnias germinate quickly, tolerate a wide range of soils, and forgive irregular watering better than most cut flowers. The main skills to learn are pinching young plants for branching and harvesting deeply. As long as you give it full sun, decent soil, and good airflow, you'll get an abundance of flowers your first season with very little experience.

Can you grow Oklahoma Scarlet in containers?▼

Yes, Oklahoma Scarlet grows well in containers at least 12 inches deep and wide. Use a quality potting mix amended with compost, and plan on watering daily during hot weather since container soil dries quickly. Container plants benefit from a half-strength liquid feed every two weeks. Limit to 1–2 plants per 12-inch pot to allow for branching, and place containers where they'll receive at least 6 hours of direct sun.

How tall does Oklahoma Scarlet zinnia get?▼

Oklahoma Scarlet typically reaches 30–40 inches tall (about 2½–3½ feet) at maturity, with a branching, multi-stemmed habit. Plants grown in fertile soil with consistent water and aggressive harvesting tend toward the upper end of that range. Despite the height, the stems are notably sturdy and rarely require staking, though market growers often run a single layer of horizontal netting at 12 inches for insurance against summer wind storms.

What's the difference between Oklahoma Scarlet and Benary's Giant Scarlet?▼

Both are cut-flower zinnias in scarlet red, but they serve different purposes. Benary's Giant Scarlet produces large 4–5 inch focal flowers on tall stems — perfect as a centerpiece bloom. Oklahoma Scarlet produces smaller 1½–2½ inch accent flowers in greater abundance, ideal as a supporting element in mixed bouquets. Oklahoma also tends to branch more heavily and produce more stems per plant, while Benary's Giants offer fewer but more dramatic blooms.

When should I plant Oklahoma Scarlet zinnia seeds?▼

Plant Oklahoma Scarlet after all danger of frost has passed and soil temperatures have reached at least 65–70°F — typically 1–2 weeks after your average last frost date. In most of the US, this falls between late April and early June. For an earlier harvest, start seeds indoors 4–6 weeks before your last frost. Avoid starting too early; zinnias dislike being root-bound and transplant best when small and actively growing.