Heirloom

Sensation Mix

Cosmos bipinnatus

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

Single flowers, 3-4" across, in lavender, pink, magenta, and white. AAS Winner. Cosmos are also known as garden cosmos.

Harvest

75-90d

Days to harvest

📅

Sun

Full sun to partial shade

☀️

Zones

2–11

USDA hardiness

🗺️

Height

2-4 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 Sensation Mix in USDA Zone 7

All Zone 7 flower →

Zone Map

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Sensation Mix · Zones 2–11

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

Spacing12-18 inches

SoilWell-drained, tolerates poor soil

WaterModerate; drought tolerant once established

SeasonWarm season annual

ColorLavender, pink, magenta, and white

Size3-4"

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
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	—
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	—

Succession Planting

Direct sow cosmos every 3 weeks starting when soil temps hit 60°F, through about 10 weeks before your first fall frost. In zone 7, that's roughly April through mid-July. They bloom 75–90 days from seed, so a July 15 sowing still gets you flowers before frost shuts things down. Stop succession once daytime highs are consistently above 90°F — germination rates drop sharply in hot soil and you'll waste the seed. Let the last planting go to seed if you want volunteers next year; Sensation Mix comes true enough from saved seed that it's worth leaving a few heads on the plant.

Complete Growing Guide

Single flowers, 3-4" across, in lavender, pink, magenta, and white. AAS Winner. Cosmos are also known as garden cosmos. According to Johnny's Selected Seeds, Sensation Mix is 75 - 90 days to maturity, annual, open pollinated. Notable features: Heirloom, Use for Cut Flowers and Bouquets, Attracts Beneficial Insects, AAS (All-America Selections) Winners.

Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: Clay, Loam (Silt), Sand. Soil pH: Alkaline (>8.0), Neutral (6.0-8.0). Drainage: Good Drainage, Occasionally Dry. Height: 2 ft. 0 in. - 4 ft. 0 in.. Spread: 2 ft. 0 in. - 3 ft. 0 in.. Spacing: 12 inches-3 feet. Growth rate: Rapid. Maintenance: Low. Propagation: Seed. Regions: Coastal, Mountains, Piedmont.

Harvesting

Sensation Mix reaches harvest at 75 - 90 days from sowing per Johnny's Selected Seeds. Expect 3-4" at peak. As an annual, harvest continues until frost ends the season.

Type: Capsule.

Storage & Preservation

For fresh Sensation Mix cosmos flowers, display in a clean vase at room temperature (65-72°F) away from direct sunlight and ripening fruit. Change water every 2-3 days for a vase life of 7-10 days. For preservation: (1) Air-dry by hanging stems upside-down in a warm, dark, well-ventilated space for 2-3 weeks to create dried arrangements; (2) Press flowers between parchment paper under heavy weight for 1-2 weeks for botanical crafts and framing; (3) Freeze flowers on a baking sheet, then store in airtight containers at 0°F for up to 6 months for later decorative use.

History & Origin

Sensation Mix is open-pollinated, meaning seed saved from healthy plants will produce true-to-type offspring. Listed in the Johnny's Selected Seeds catalog.

Origin: Mexico and southwest North America

Advantages

+AAS Winner status confirms superior performance and ornamental qualities
+Large 3-4 inch flowers create bold visual impact in gardens
+Vibrant color mix of lavender, pink, magenta, and white
+Quick 75-90 day maturity allows multiple plantings per season
+Easy growing difficulty makes it ideal for beginner gardeners

Considerations

-Tall plants often require staking or support in windy locations
-Self-seeds prolifically, potentially becoming invasive in future seasons
-Thin stems prone to breaking during heavy rain or storms

Companion Plants

Marigolds (especially Tagetes patula) are the most practical neighbor here — their root secretions deter nematodes, and the open blooms pull in the same hoverflies and parasitic wasps that keep aphid pressure off cosmos. Sweet alyssum does similar pest-suppression work through nectar, but it also fills the low horizontal layer that cosmos — at 2 to 4 feet — leaves completely open. Nasturtiums are worth planting at the bed edge specifically because Myzus persicae aphids prefer them over cosmos; they'll cluster on the nasturtiums first, giving you an early-warning system. Give black walnut a wide berth: juglone leaches from the roots and hulls into surrounding soil, and cosmos are sensitive enough that you'll see stunting and dieback well before you figure out why. Fennel is a subtler problem — its allelopathic root exudates suppress germination of nearby annuals, which matters a lot when you're direct-sowing cosmos.

Plant Together

Marigolds

Repel aphids, whiteflies, and other pests while attracting beneficial insects

Sweet Alyssum

Attracts beneficial insects like hoverflies and parasitic wasps for natural pest control

Nasturtiums

Act as trap crops for aphids and cucumber beetles, drawing pests away from cosmos

Zinnias

Attract pollinators and beneficial insects while providing complementary colors and bloom times

Cleome

Attracts butterflies and beneficial insects while providing vertical structure and contrast

Sunflowers

Provide natural support structure and attract pollinators and beneficial birds

Lavender

Repels aphids, moths, and other pests while attracting beneficial pollinators

Basil

Repels aphids, spider mites, and thrips that commonly affect cosmos

Keep Apart

Black Walnut

Releases juglone toxin that inhibits cosmos growth and can cause stunting or death

Fennel

Produces allelopathic compounds that inhibit growth and development of cosmos

Large Shade Trees

Create excessive shade that reduces flowering and causes leggy, weak growth in sun-loving cosmos

Pests & Disease Resistance

Common Pests

Aphids, spider mites, whiteflies

Diseases

Powdery mildew, rust, root rot in poorly drained soil

Troubleshooting Sensation Mix

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

White powdery coating on upper leaf surfaces, usually appearing mid-summer when nights cool down

Likely Causes

Powdery mildew (Erysiphe cichoracearum) — fungal spores spread by wind, thrives when humidity is high but leaves stay dry
Crowded planting at less than 12-inch spacing that cuts airflow

What to Do

1.Thin plants to at least 12 inches apart if you haven't already — airflow is your first fix
2.Spray affected foliage with a diluted baking soda solution (1 tablespoon per gallon of water) or a neem oil product early in the morning
3.Pull and trash heavily infected stems; don't compost them

Tiny clustered insects on new growth, stems sticky or shiny, flower buds deformed

Likely Causes

Aphid infestation (commonly green peach aphid, Myzus persicae) — they colonize fast on soft new growth
Absence of natural predators, often because nearby plants lack nectar sources to support beneficial insects

What to Do

1.Knock aphids off with a firm spray of water from the hose — do this three mornings in a row
2.If they persist, apply insecticidal soap directly to the colonies, coating undersides of leaves
3.Plant sweet alyssum within a few feet going forward; it draws parasitic wasps that keep aphid populations down

Plants wilting and yellowing at the base despite adequate watering, stems soft or discolored near soil level

Likely Causes

Root rot (commonly Pythium or Rhizoctonia species) from waterlogged or poorly drained soil
Planting in a low spot that holds water after rain

What to Do

1.Pull the affected plant — there's no saving it once root rot takes hold — and check the roots for brown, mushy tissue to confirm
2.Amend the bed with coarse sand or pine bark to improve drainage before replanting
3.Direct sow cosmos rather than transplanting in marginal soil; they establish a sturdier root system from seed

Frequently Asked Questions

How long do Sensation Mix cosmos flowers last in a vase?▼

Sensation Mix cosmos typically last 7-10 days in a vase with proper care. Keep stems in fresh, room-temperature water and change the water every 2-3 days. Remove any leaves below the waterline to prevent bacterial growth. Trim stems at a 45-degree angle for better water absorption. Keeping flowers away from direct sunlight and ripening fruit will extend their vase life.

Is Sensation Mix cosmos good for beginners?▼

Yes, Sensation Mix cosmos are excellent for beginners. They're labeled as easy to grow and are an AAS (All-America Selections) Award Winner, indicating superior performance. These flowers thrive in full sun to partial shade, tolerate poor soil, require minimal maintenance, and produce abundant blooms throughout the season. They're ideal for new gardeners seeking reliable, showy results.

Can you grow Sensation Mix cosmos in containers?▼

Yes, Sensation Mix cosmos grow well in containers. Use large pots (at least 12 inches in diameter) with well-draining potting soil. Place containers in a location receiving 4-6+ hours of sunlight daily. Water regularly to keep soil consistently moist but not waterlogged. Container-grown cosmos may need occasional staking as they mature and produce flower-heavy stems.

When should I plant Sensation Mix cosmos seeds?▼

Direct sow Sensation Mix cosmos seeds in the garden after the last spring frost when soil has warmed. Seeds germinate quickly in warm conditions. Alternatively, start seeds indoors 6-8 weeks before your last frost date and transplant seedlings after frost danger has passed. Cosmos prefer warm soil and sunlight, so timing matters for successful germination and strong growth.

How tall do Sensation Mix cosmos grow?▼

Sensation Mix cosmos typically grow to 24-36 inches tall with a similar spread, producing flowers 3-4 inches across. Their height makes them excellent for back borders, cutting gardens, and tall arrangements. The plant's bushy growth habit and prolific blooming create a full, attractive appearance suitable for mixed beds and cottage gardens.

What colors come in the Sensation Mix variety?▼

Sensation Mix cosmos produce single flowers in four beautiful colors: lavender, pink, magenta, and white. Each plant may produce flowers in all colors or concentrate on specific hues, creating a naturally colorful display. This color variety makes them versatile for garden design and attractive as fresh cut flowers for mixed bouquets.