Heirloom

Tower Custom Mix

Callistephus chinensis

All the elegance and beauty of peonies and garden mums in an easy-to-grow annual. Bloom size avg. 2-3" with 13-20 stems per plant. Tower features uniform bloom time and plant height across the series and mix. Colors include yellow, chamois, white, red, violet, silver, blue, cherry rose, dusty pink, light blue, and salmon. Colors are subject to slight variance due to seed availability. Also known as summer aster.

Harvest

110-120d

Days to harvest

📅

Sun

Full sun to partial shade

☀️

Zones

2–11

USDA hardiness

🗺️

Height

1-3 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 Tower Custom Mix in USDA Zone 7

All Zone 7 flower →

Zone Map

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Tower Custom Mix · Zones 2–11

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

Spacing12-18 inches

SoilWell-draining soil, tolerates most soil types

WaterRegular, consistent moisture; avoid waterlogging

SeasonWarm season annual

ColorMulti-color mix: yellow, white, red, blue, violet, silver, cherry rose, dusty pink, light blue, chamois, and salmon

Size2-3"

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

Tower Custom Mix runs 110-120 days to bloom, so in zone 7 you only get two realistic windows. Start seeds indoors in late February or early March, transplant after last frost (around April 1-15 for most of Georgia), and you'll have flowers by mid-to-late summer. For a fall flush — which is often the better show once the heat has backed off — start a second round indoors in late April and get those plants in the ground by early June. September and October blooms on China asters are genuinely worth planning for.

Don't push direct sowing past June. Germination wants soil temps around 70°F, and plants started much later won't reach 110 days before a killing frost arrives in November. A third succession isn't worth attempting; the math doesn't work out in this climate.

Complete Growing Guide

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, High Organic Matter, Loam (Silt), Sand. Soil pH: Acid (<6.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 1 ft. 0 in. - 3 ft. 0 in.. Spread: 1 ft. 0 in. - 1 ft. 6 in.. Spacing: Less than 12 inches. Growth rate: Rapid. Maintenance: Medium. Regions: Coastal, Mountains, Piedmont.

Harvesting

The fruit is a rough-textured, glandular, purple-mottled cypsela that turns gray with age.

Storage & Preservation

Tower Custom Mix flowers should be cut in the early morning when blooms are freshly opened and placed immediately in cool water. Store in a cool room (65-72°F) away from ripening fruit and direct sunlight. Vase water should be changed every 2-3 days for maximum freshness; blooms typically last 7-10 days as cut flowers. For preservation, air-dry stems by hanging upside-down in a warm, dark, well-ventilated space for 2-3 weeks for dried arrangements. Alternatively, press individual blooms between parchment paper under weight for 1-2 weeks to create pressed flower crafts. Silica gel drying is another option for preserving color and form.

History & Origin

Origin: China and Southern Russia

Advantages

+Produces 13-20 stems per plant for abundant cutting potential
+Uniform bloom time and height simplify garden planning and harvesting
+Eleven vibrant colors in one mix provide striking visual variety
+Easy-to-grow annual requires minimal experience or special care requirements
+2-3 inch blooms resemble peonies with elegant, full-petaled appearance

Considerations

-Color variance occurs due to seed availability affecting consistency
-Susceptible to powdery mildew in humid or crowded growing conditions
-Requires 110-120 days to bloom, limiting short-season growing regions
-Flowers may require staking or support in windy locations

Companion Plants

Marigolds (especially Tagetes patula) are the most practical companion here — their root secretions suppress nematode populations in the soil, and since Fusarium wilt is a standing threat to China asters, anything that reduces root-zone stress is worth the bed space. Sweet Alyssum draws in parasitic wasps and hoverflies that knock back aphids, which can vector aster yellows phytoplasma. Chives planted at the bed edge do similar work in about 6 inches of lateral space. Nasturtiums pull double duty as a trap crop for aphids and as a low visual fill between taller aster stems.

Fennel releases allelopathic compounds from both roots and foliage that stunt most nearby annuals, asters included — and in our zone 7 Georgia garden, where cutting-flower beds often sit right next to herb plantings, that's a mistake that's easy to make and takes weeks to diagnose. Black walnut (Juglans nigra) produces juglone, a compound toxic to a wide range of plants; don't site asters within 50 feet of a black walnut's drip line.

Plant Together

Marigolds

Repel aphids, whiteflies, and nematodes 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 while attracting pollinators

Lavender

Repels moths, fleas, and mosquitoes while attracting bees and butterflies

Zinnia

Attracts butterflies, bees, and beneficial predatory insects

Cosmos

Attracts beneficial insects and provides structural support for climbing flowers

Borage

Attracts pollinators and beneficial insects while improving soil nutrients

Chives

Repel aphids and other soft-bodied insects with their strong scent

Keep Apart

Black Walnut

Releases juglone toxin that inhibits growth and can kill many flowering plants

Eucalyptus

Produces allelopathic compounds that suppress growth of nearby plants

Fennel

Inhibits growth of most garden plants through allelopathic root secretions

Troubleshooting Tower Custom Mix

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

Seedlings collapse at soil level, stems pinched and dark at the base, 7-14 days after germination

Likely Causes

Damping off (Pythium or Rhizoctonia spp.) — fungal complex that thrives in cold, wet, poorly ventilated trays
Overwatering or trays without drainage

What to Do

1.Toss the affected tray — there's no saving collapsed seedlings; start fresh in sterile seed-starting mix
2.Water from the bottom only, and run a small fan near your trays to keep air moving
3.Don't sow too early indoors; China asters don't need more than 6-8 weeks before transplant

Leaves yellowing, plant stunted, wilting despite adequate soil moisture — sometimes one side of the plant goes before the other

Likely Causes

Fusarium wilt (Fusarium oxysporum f. sp. callistephi) — soil-borne, persists for years, enters through roots
Aster yellows phytoplasma — transmitted by aster leafhoppers (Macrosteles quadrilineatus)

What to Do

1.Pull and trash any plant showing one-sided wilt or yellowing — don't compost it
2.Rotate asters out of that bed for at least 3 years; Fusarium doesn't leave on its own
3.Cover transplants with row fabric through early summer to block leafhoppers and reduce aster yellows pressure

White powdery coating on upper leaf surfaces, usually appearing in late summer as nights cool below 65°F

Likely Causes

Powdery mildew (Erysiphe cichoracearum) — spreads via airborne spores in dry weather with cool nights
Crowded planting at less than 12-inch spacing that cuts airflow between stems

What to Do

1.Space plants 12-18 inches apart at transplant — crowding is the main risk factor here
2.Apply potassium bicarbonate (per label rate) or a baking soda solution at 1 tablespoon per gallon at first sign
3.Strip and bag the worst-affected leaves; the infection won't reverse, but you can slow the spread

Ragged holes in petals and leaves, or flower buds failing to open, with no visible insects during the day

Likely Causes

Earwigs (Forficula auricularia) — feed at night, hide in mulch or debris during the day
Tarnished plant bug (Lygus lineolaris) — pierces buds, causing distorted or blind flower heads

What to Do

1.Set a rolled-damp-newspaper trap near the base of plants at night; check and drop contents into soapy water each morning
2.For tarnished plant bug, keep the bed edges weeded — especially wild mustard and dock, which host them over winter
3.Cut flowers at the half-open stage; they'll finish indoors away from pest pressure and last longer in the vase anyway

Frequently Asked Questions

How long do Tower Custom Mix flowers last in a vase?▼

When properly cut and cared for, Tower Custom Mix blooms typically last 7-10 days in fresh water. To extend vase life, cut stems at a 45-degree angle, remove lower foliage, use fresh cool water, and change the water every 2-3 days. Adding flower food can help maximize longevity and vibrancy of the blooms.

Is Tower Custom Mix a good flower for beginner gardeners?▼

Yes, Tower Custom Mix is excellent for beginners. It's an easy-to-grow annual that thrives in full sun to partial shade (4-6+ hours minimum). The variety produces uniform plant height and synchronized blooming, reducing the need for complex maintenance. Simply provide regular water and deadhead spent flowers to encourage continuous blooming throughout the season.

Can you grow Tower Custom Mix flowers in containers?▼

Yes, Tower Custom Mix grows well in containers. Its uniform, compact plant height makes it ideal for pots, window boxes, and planters. Use well-draining potting soil and select containers at least 12 inches deep. Place in a location receiving 4-6+ hours of sunlight daily, water regularly to keep soil consistently moist but not waterlogged, and deadhead regularly for best blooming.

When should I plant Tower Custom Mix seeds?▼

Sow Tower Custom Mix seeds indoors 6-8 weeks before your last spring frost date, or direct sow outdoors after the last frost when soil has warmed. Seeds germinate in 7-14 days under proper conditions. These heat-loving annuals prefer warm soil, so avoid planting too early. Once established, they bloom reliably from mid-summer through fall.

What colors are included in the Tower Custom Mix?▼

Tower Custom Mix offers a beautiful spectrum of 12+ colors including yellow, white, red, blue, violet, silver, cherry rose, dusty pink, light blue, chamois, and salmon. Each plant produces 13-20 stems with 2-3 inch blooms, creating a stunning mixed display. Colors may vary slightly based on seed availability from year to year.

How often should I deadhead Tower Custom Mix flowers?▼

Deadhead spent blooms regularly—ideally every few days—to encourage continuous flower production throughout the season. Removing faded flowers signals the plant to produce more blooms rather than setting seed. This practice extends your flowering period and keeps plants looking full and vibrant, maximizing the garden display.