Ashworth
Zea mays 'Ashworth'
A remarkable cold-tolerant heirloom sweet corn specifically bred for northern gardens and short growing seasons. This hardy variety can germinate in cooler soils and tolerate light frosts, making it possible to grow sweet corn in challenging climates where other varieties fail. The compact plants produce flavorful ears with excellent eating quality despite the shorter season requirements.
Harvest
60-70d
Days to harvest
Sun
Full sun
Zones
2–11
USDA hardiness
Height
5-8 feet
Planting Timeline
Showing dates for Ashworth in USDA Zone 7
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Ashworth · Zones 2–11
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | — | — | June – July | September – October |
| Zone 4 | — | — | June – July | August – October |
| Zone 5 | — | — | May – June | August – October |
| Zone 6 | — | — | May – June | August – September |
| Zone 7 | — | — | April – June | July – September |
| Zone 8 | — | — | April – May | July – August |
| Zone 9 | — | — | March – April | June – July |
| Zone 10 | — | — | February – April | May – July |
| Zone 1 | — | — | July – August | October – August |
| Zone 2 | — | — | June – August | September – September |
| Zone 11 | — | — | January – March | April – June |
| Zone 12 | — | — | January – March | April – June |
| Zone 13 | — | — | January – March | April – June |
Succession Planting
Direct sow Ashworth every 14 days starting around April 15 in zone 7, and make your last sowing by June 20 — that keeps harvest inside the July-to-September window before ears push past their prime. The UGA Vegetable Garden Calendar suggests a third corn sowing in May, which lines up well; three plantings spaced two weeks apart gives you a 6-week harvest spread instead of everything ripening at once.
Stop sowing once daytime highs are regularly above 90°F. Ashworth matures in 60–70 days, so a late June sowing can still get through germination before the worst heat, but silk development in August will tank pollination and kernel fill. If you're in zone 7b or warmer, treat June 20 as a firm cutoff.
Complete Growing Guide
Ashworth's cold tolerance means you can direct sow seeds 1-2 weeks earlier than standard sweet corn varieties, even when soil temperatures hover around 50°F rather than waiting for the typical 60°F minimum. Plant in full sun with well-draining soil amended with compost, as cooler conditions slow nutrient availability. This variety's compact stature (5-8 feet) makes it ideal for tight spaces but requires consistent moisture during the critical silking stage—irregular watering increases the risk of incomplete kernel development. Watch for corn earworm and fall armyworm as usual, but Ashworth's shorter season actually works in your favor by avoiding late-summer pest populations. The main cultivar-specific tendency is susceptibility to damping-off in waterlogged seedbeds, so ensure excellent drainage when starting seeds indoors or direct sowing in cold, wet springs. Practical tip: succession plant every two weeks through early summer to extend your harvest rather than relying on a single planting, since these short-season plants mature rapidly once temperatures warm.
Light: Full sun (6 or more hours of direct sunlight a day). Soil: Clay, High Organic Matter, Loam (Silt). Soil pH: Acid (<6.0), Neutral (6.0-8.0). Drainage: Good Drainage. Height: 5 ft. 0 in. - 8 ft. 0 in.. Spread: 1 ft. 0 in. - 2 ft. 0 in.. Spacing: 12 inches-3 feet. Growth rate: Rapid. Maintenance: Medium. Propagation: Seed. Regions: Coastal, Mountains, Piedmont.
Harvesting
Ashworth ears reach peak harvest when the husks turn deep green and feel slightly papery, while the silks darken to brown or black. At this stage, kernels should be plump and milky when punctured, indicating optimal sugar content before conversion to starch. This early-maturing variety produces ears in concentrated flushes rather than continuous succession, so plan to harvest most ears within a narrow window of 2–3 days for best quality. For northern gardeners, pick ears in the morning after dew dries but before heat builds, as cooler temperatures help preserve sweetness and tenderness in this cold-climate cultivar.
Color: Gold/Yellow. Type: Caryopsis. Length: > 3 inches. Width: 1-3 inches.
Garden value: Edible, Showy
Harvest time: Fall
Edibility: Edibile
Storage & Preservation
Use Ashworth corn immediately after harvest for peak sweetness—sugars convert to starch rapidly at room temperature. If immediate use isn't possible, refrigerate unhusked ears up to 3 days, or husk and blanch immediately for longer storage.
For freezing, blanch ears in boiling water for 4 minutes (small ears) to 6 minutes (large ears), then plunge in ice water. Cut kernels from cob or freeze whole ears in freezer bags. Frozen Ashworth corn maintains quality for 8-10 months.
The variety's naturally tender kernels make it excellent for cream-style corn preservation. Cut kernels at half-depth, then scrape cobs with a knife back to extract the creamy pulp. This method works particularly well for pressure canning, as Ashworth's sweet, tender nature creates a superior creamed corn compared to field varieties. The early harvest timing also makes it perfect for pickled corn relish when combined with late-summer vegetables.
History & Origin
The 'Ashworth' sweet corn variety represents a cold-hardy heirloom selection whose precise breeding history remains incompletely documented in mainstream horticultural records. The variety appears to have emerged from northern gardening traditions and early-to-mid twentieth-century breeding efforts focused on extending corn cultivation into regions with short growing seasons. While specific breeder attribution and introduction year are unclear, 'Ashworth' exemplifies the lineage of northern-adapted sweet corn varieties developed through selection for early maturity and frost tolerance. The variety's survival in the heirloom seed trade suggests it originated from practical farmer selection and regional seed company work, though definitive documentation of its breeding program or originating institution remains elusive.
Origin: Mexico
Advantages
- +Cold-tolerant germination allows planting in cool northern soils earlier
- +Matures in just 60-70 days, perfect for short growing seasons
- +Compact plants fit well in smaller or space-limited gardens
- +Excellent flavor and tenderness despite early maturity requirements
- +Tolerates light frosts that would kill standard sweet corn varieties
Considerations
- -Susceptible to seedling blights in wet, cool spring conditions
- -Seed corn maggot and cutworm pressure requires preventive measures
- -Lower overall yield compared to full-season sweet corn varieties
- -Vulnerable to bacterial leaf streak in humid growing environments
Companion Plants
Beans, squash, and corn together is a real working system, not just folklore: beans fix atmospheric nitrogen that Ashworth — a heavy feeder at 5–8 feet tall — pulls hard from the soil all season, and squash canopies shade out weeds and hold moisture through the dry July stretches we get here in the Georgia piedmont. Tagetes patula marigolds and nasturtiums in the surrounding beds do measurable work against aphids and cucumber beetles. Fennel is genuinely allelopathic and suppresses germination of most vegetables planted within a few feet, so keep it on the far end of the garden entirely. Tomatoes are a bad neighbor for a different reason — they share mid-season water and fertility demands that peak at exactly the same time, and the corn flea beetle pressure that hits sweet corn can spill right over.
Plant Together
Beans
Fix nitrogen in soil that corn can utilize, corn provides natural support for climbing beans
Squash
Large leaves suppress weeds and retain soil moisture, completes the Three Sisters planting method
Marigolds
Repel corn earworms, aphids, and other harmful insects while attracting beneficial predators
Nasturtiums
Act as trap crop for aphids and cucumber beetles, repel squash bugs and corn borers
Sunflowers
Attract beneficial insects and birds that eat corn pests, provide windbreak protection
Dill
Attracts beneficial wasps that parasitize corn borers and other pest larvae
Parsley
Attracts beneficial insects like hoverflies and parasitic wasps that control aphids
Radishes
Help break up compacted soil with their taproots, mature quickly without competing for space
Keep Apart
Black Walnut Trees
Release juglone toxin that severely stunts corn growth and can kill plants
Tomatoes
Both attract corn earworms and compete for similar nutrients, increasing pest pressure
Fennel
Releases allelopathic compounds that inhibit corn germination and growth
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #168538)
Pests & Disease Resistance
Resistance
Good cold tolerance and resistance to cool weather diseases
Common Pests
Seed corn maggot, cutworms, corn flea beetle
Diseases
Seedling blights, bacterial leaf streak
Troubleshooting Ashworth
What you'll see, why it happens, and what to do about it.
Seeds rot in the ground or sprout poorly, with sparse, uneven stands in the first 7-12 days after sowing
Likely Causes
- Seed corn maggot (Delia platura) — larvae feed on germinating seeds, especially in cool, wet soil with high organic matter
- Seedling blight complex — soil-borne fungi (Pythium, Fusarium) that thrive when soil temps drop below 55°F at planting
What to Do
- 1.Wait until soil temperature is consistently at or above 60°F before direct sowing — in zone 7 that's usually mid-April at the earliest
- 2.Avoid working in heavy amounts of fresh manure or green material right before planting; it draws seed corn maggot adults to lay eggs
- 3.If you've had stand failures before, treat seed with a thiram-based fungicide dust or source pre-treated seed for that block
Seedlings cut off cleanly at the soil line overnight, 1-2 weeks after germination
Likely Causes
- Cutworms (Agrotis or Peridroma spp.) — fat, gray-brown caterpillars that curl up in the soil by day and feed at night
What to Do
- 1.Dig around the base of cut plants — you'll usually find the cutworm within 2 inches of the surface; hand-pick and destroy
- 2.Press cardboard or plastic collar barriers around newly emerged seedlings, sinking them 1 inch into the soil
- 3.Broadcast Bacillus thuringiensis (Bt) or spinosad granules on the soil surface around affected rows at dusk
Tiny, ragged shothole damage on leaves of young plants, with a bronze or stippled appearance starting around weeks 2-4
Likely Causes
- Corn flea beetle (Chaetocnema pulicaria) — small, shiny black beetles that jump when disturbed; feeding also vectors Stewart's wilt (Pantoea stewartii)
- High overwintering populations after a mild winter — NC State Extension notes that flea beetle pressure correlates with warm December-February temperatures
What to Do
- 1.Scout daily once plants emerge; if more than 50% of seedlings show feeding damage, apply a pyrethrin or kaolin clay spray
- 2.Float row cover over newly emerged corn for the first 3 weeks — pull it before tasseling so pollination isn't blocked
- 3.If leaves develop pale, water-soaked streaking after flea beetle feeding, that's likely Stewart's wilt; pull and trash those plants rather than composting them
Frequently Asked Questions
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Growing Guides from Wind River Greens
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Sources & References
External authority sources used in compiling this guide.
See the Methodology page for how this data is sourced, what's AI-assisted, and known limitations.