Tower Yellow
Callistephus chinensis
All the elegance and beauty of peonies and garden mums in an easy-to-grow annual. Buttercream-yellow blooms avg. 2-3" with 13-20 stems per plant. Tower features uniform bloom time and plant height across the series and mix. 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
Showing dates for Tower Yellow in USDA Zone 7
All Zone 7 flower →Zone Map
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Tower Yellow · Zones 2–11
Growing Details
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 Yellow runs 110-120 days from seed to bloom, which is long for a warm-season annual — long enough that a single sowing gives you one flush and you're done. If you want cut flowers from July through September, start two rounds indoors: the first in late February, transplanting out in late April after the last frost date; the second about 4 weeks later in late March, transplanting in May. That spacing staggers bloom time enough to matter without overlapping so much that you're overwhelmed at once.
Don't push direct sowing past early June. China asters are finicky about setting buds during heat — sustained daytime highs above 85°F tend to stall bud development or cause distorted blooms. Plants started too late run straight into that window right at the critical stage. Two indoor rounds is enough for most gardeners to carry a steady supply through to first frost.
Complete Growing Guide
All the elegance and beauty of peonies and garden mums in an easy-to-grow annual. Buttercream-yellow blooms avg. 2-3" with 13-20 stems per plant. Tower features uniform bloom time and plant height across the series and mix. Also known as summer aster. According to Johnny's Selected Seeds, Tower Yellow is 110 - 120 days to maturity, annual, open pollinated. Notable features: Use for Cut Flowers and Bouquets.
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
Tower Yellow reaches harvest at 110 - 120 days from sowing per Johnny's Selected Seeds. Expect 2-3" at peak. As an annual, harvest continues until frost ends the season.
The fruit is a rough-textured, glandular, purple-mottled cypsela that turns gray with age.
Storage & Preservation
Store Tower Yellow cut flowers in a cool location, ideally in a refrigerator at 35-40°F with 85-90% humidity to extend vase life to 7-10 days. Keep stems in clean, fresh water with floral preservative. For longer preservation, dry flowers by hanging bundles upside-down in a cool, dark, well-ventilated space for 2-3 weeks until completely dry, then store in airtight containers. Alternatively, press individual blooms between parchment paper under weight for 1-2 weeks to preserve for crafts or arrangements.
History & Origin
Tower Yellow is open-pollinated, meaning seed saved from healthy plants will produce true-to-type offspring. Listed in the Johnny's Selected Seeds catalog.
Origin: China and Southern Russia
Advantages
- +Buttercream-yellow blooms resemble peonies and mums without difficulty
- +13-20 stems per plant provide excellent cut flower yields
- +Uniform bloom time and height simplify garden design and planning
- +Easy to grow annual requires minimal care or expertise
- +110-120 day season fits well into most growing regions
Considerations
- -Yellow blooms may fade in intense afternoon sun exposure
- -Asters susceptible to powdery mildew in humid conditions
- -Requires staking or support as stems reach full height
- -Prefers well-drained soil and dislikes waterlogged conditions
Companion Plants
Marigolds and nasturtiums are the most practical companions here. Marigolds — especially compact French types like 'Petite Yellow' — deter aphids and thrips through scent, which matters because aster leafhoppers (Macrosteles quadrilineatus) and aphids are Tower Yellow's biggest insect headaches. Nasturtiums work differently: aphids tend to pile onto them first, which gives you an early warning and a concentrated target to cut off before the infestation reaches your China asters. Neither competes hard for root space alongside a shallow-rooted annual like Tower Yellow.
Zinnias, cosmos, and sweet alyssum pull their weight by drawing in parasitic wasps and hoverflies that feed on the same aphids troubling the asters. Sweet alyssum is particularly reliable — it tops out around 6-8 inches, so it won't shade Tower Yellow, and its bloom window is long enough to keep beneficial insects on patrol through most of the summer. Sunflowers can anchor a border or backdrop, but plant them at least 24 inches back so their canopy doesn't steal light from plants that need 4-6 hours minimum.
The three to keep at a distance are black walnut, fennel, and eucalyptus. Black walnut releases juglone through its roots and decomposing leaf litter — enough to stunt or kill many annuals planted within the tree's drip line. Fennel is broadly allelopathic and suppresses neighbors through root exudates; it's worth isolating in its own bed no matter what you're growing nearby. Eucalyptus releases volatile compounds into the surrounding soil that can interfere with root development and germination in neighboring plants.
Plant Together
Marigolds
Repel nematodes and aphids while attracting beneficial insects
Nasturtiums
Act as trap crop for aphids and cucumber beetles
Zinnias
Attract pollinators and beneficial predatory insects
Cosmos
Provide habitat for beneficial insects and complement yellow blooms
Sweet Alyssum
Attracts parasitic wasps and other beneficial predators
Lavender
Repels moths, fleas, and mosquitoes with aromatic oils
Sunflowers
Provide support structure and attract pollinators
Petunias
Repel aphids, tomato hornworms, and squash bugs
Keep Apart
Black Walnut Trees
Release juglone toxin that inhibits growth of many flowers
Fennel
Allelopathic properties inhibit growth of nearby flowering plants
Eucalyptus
Releases chemicals that suppress germination and growth of other plants
Troubleshooting Tower Yellow
What you'll see, why it happens, and what to do about it.
Seedlings collapse at soil level, stems look pinched or water-soaked at the base
Likely Causes
- Damping off — typically Pythium or Rhizoctonia fungi thriving in soggy, poorly ventilated flats
- Overwatering combined with low air circulation around the tray
What to Do
- 1.Water only when the top inch of soil is dry, and bottom-water when possible to keep the stem base dry
- 2.Run a small fan near your seedling trays for at least a few hours each day
- 3.Toss the affected seedlings and any adjacent ones — don't try to save them
Stunted plants with distorted, curled new growth; tiny insects visible on undersides of leaves
Likely Causes
- Aster yellows phytoplasma — transmitted by the aster leafhopper (Macrosteles quadrilineatus)
- Aphid infestation causing direct feeding damage and potentially transmitting additional pathogens
What to Do
- 1.Pull and bag any plant showing aster yellows symptoms immediately — there is no cure and leafhoppers will spread it to healthy plants within days
- 2.For aphids, knock them off with a firm stream of water or apply insecticidal soap every 5-7 days until populations drop
- 3.Drape row cover over young transplants to cut leafhopper pressure during the first few weeks after planting
Gray fuzzy mold forming on petals and upper leaves, especially after cool wet weather
Likely Causes
- Botrytis blight (Botrytis cinerea) — a fungal disease that moves fast in cool, humid conditions below 70°F
- Overcrowded planting that traps moisture between plants
What to Do
- 1.Space plants at least 18 inches apart to let air move through — the wider end of the recommended spacing pays off here
- 2.Deadhead spent blooms promptly; Botrytis cinerea colonizes dying tissue before it moves to healthy growth
- 3.Strip and bin (don't compost) any affected leaves or flowers, then apply a copper-based fungicide if the problem is spreading
Leaves developing small, angular yellow spots that turn brown; powdery or rusty coating on leaf undersides
Likely Causes
- Powdery mildew (Golovinomyces cichoracearum) — common late in the season when nights cool and days stay warm
- Aster rust (Coleosporium asterum) — less common but produces orange pustules on leaf undersides
What to Do
- 1.For powdery mildew, apply a baking soda spray (1 tablespoon per gallon of water with a few drops of dish soap) weekly, or switch to a sulfur-based fungicide if it's gaining ground
- 2.For rust, remove affected leaves immediately and stop overhead watering — keep water off the foliage entirely
- 3.Both problems worsen with plant stress, so make sure Tower Yellow is getting consistent moisture and isn't crowded at the 18-24 inch spacing
Frequently Asked Questions
How long do Tower Yellow flowers last in a vase?▼
Is Tower Yellow a good variety for beginners?▼
Can you grow Tower Yellow in containers?▼
When should I plant Tower Yellow seeds?▼
How many flowers does Tower Yellow produce per plant?▼
What makes Tower Yellow different from regular mums?▼
Growing Guides from Wind River Greens
Where to Buy Seeds
Sources & References
External authority sources used in compiling this guide.
- BreederJohnny's Selected Seeds
See the Methodology page for how this data is sourced, what's AI-assisted, and known limitations.