Planting Timeline
Showing dates for Candy Onion in USDA Zone 7
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Candy Onion · Zones 4–9
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 4 | February – March | April – May | April – May | August – September |
| Zone 5 | February – March | April – May | March – April | July – September |
| Zone 6 | January – February | March – April | March – April | July – September |
| Zone 7 | January – February | March – April | February – March | June – August |
| Zone 8 | December – January | February – March | January – February | May – July |
| Zone 9 | November – December | January – February | December – January | April – June |
Complete Growing Guide
Start your Candy Onion seeds indoors 10-12 weeks before your last expected frost date. Sow seeds ¼ inch deep in seed-starting mix, keeping soil temperature around 60-65°F for optimal germination. These intermediate-day onions need 12-14 hours of daylight to begin bulbing, making them perfect for zones 5-7.
Prepare your planting bed by working in 2-3 inches of well-aged compost or rotted manure. Candy Onions demand rich, loose soil with excellent drainage—standing water will cause bulb rot. Test your soil pH; onions prefer 6.0-7.0 for best nutrient uptake. If your soil is heavy clay, consider raised beds or mounded rows.
Transplant seedlings when they're pencil-thick and soil temperature reaches 50°F consistently. Space plants 4-6 inches apart in rows 12 inches apart—closer spacing produces smaller bulbs, wider spacing yields larger ones. Plant at the same depth they were growing indoors; burying too deep restricts bulb development.
Fertilize with a balanced 10-10-10 fertilizer at planting, then switch to high-nitrogen fertilizer every 3-4 weeks until midsummer. Stop nitrogen feeding when bulbs begin swelling (usually late June in most zones) to prevent soft necks and poor storage.
Maintain consistent moisture throughout the growing season—irregular watering causes split bulbs and bitter flavor. Apply 1-2 inches weekly, watering at soil level to prevent foliar diseases. Mulch around plants to retain moisture and suppress weeds, but keep mulch 2 inches away from bulb necks.
Avoid the common mistake of harvesting too early. Candy Onions need the full 100-110 days to develop their signature sweetness. Also resist the urge to hill soil around developing bulbs—onions need their shoulders exposed to sunlight for proper curing.
For maximum yields, hand-weed carefully around plants since onions have shallow roots. Consider companion planting with carrots or lettuce to maximize garden space, but avoid planting near beans or peas which can stunt onion growth.
Harvesting
Harvest Candy Onions when 50-75% of the green tops begin falling over naturally, typically 100-110 days from transplanting. Don't wait for all tops to brown—some may stay green while bulbs reach full size. The bulbs should feel firm when gently squeezed at soil level, with papery golden-yellow skin visible at the shoulders.
Perform the 'twist test' by gently rotating the bulb—it should move freely in the soil when ready. Harvest on a dry morning after dew has evaporated but before afternoon heat. Carefully lift bulbs with a garden fork, working 4-6 inches away from each bulb to avoid nicking the skin. Damaged onions won't store well, so handle gently.
Brush off excess soil but don't remove roots or cut tops immediately. Lay bulbs in a single layer in a warm, dry, well-ventilated area for initial curing. After 2-3 weeks, trim tops to 1 inch and roots to ½ inch once necks are completely dry and papery.
Storage & Preservation
Fresh Candy Onions store for 2-4 months in cool (32-40°F), dry conditions with good air circulation. Unlike storage onions, these sweet varieties have higher water content and softer necks, limiting long-term storage. Store cured bulbs in mesh bags or ventilated crates—never in plastic bags which trap moisture.
For shorter-term storage, keep uncured bulbs refrigerated for up to 3 weeks, perfect for showcasing their sweet, crisp texture. Slice and freeze on baking sheets, then transfer to freezer bags for 8-10 months—ideal for cooked dishes though texture becomes soft. Candy Onions make excellent pickled onions due to their mild flavor and firm texture. Their low sulfur content also makes them perfect for dehydrating into sweet onion powder, though they're honestly too delicious fresh to preserve extensively.
History & Origin
Candy Onion represents the modern era of sweet onion breeding, developed in the late 20th century as plant breeders focused on creating onions specifically for fresh consumption rather than storage. This hybrid emerged from breeding programs that prioritized reducing sulfur compounds responsible for onions' sharp bite and tear-inducing properties.
The variety was bred to combine the sweetness traits found in famous regional onions like Vidalia and Walla Walla with the reliability and uniformity that home gardeners need. Unlike these location-specific sweet onions that depend on unique soil conditions, Candy Onion was designed to produce consistent sweetness across various growing conditions.
Modern sweet onion breeding really accelerated in the 1980s and 1990s as consumer demand grew for milder, more versatile onions. Candy Onion exemplifies this trend toward 'dessert onions'—varieties so mild they can be eaten raw like fruit. The variety's development reflects changing American eating habits, where fresh salsas, salads, and lighter cooking styles created demand for onions that enhance rather than overpower other flavors.
Advantages
- +Exceptionally sweet flavor allows eating raw like an apple without tears or harsh aftertaste
- +Excellent uniformity produces consistently sized, well-shaped bulbs perfect for market gardening
- +Good hybrid vigor provides reliable germination and strong disease resistance compared to open-pollinated varieties
- +Crisp texture holds up beautifully in fresh applications like salsas and salads
- +Intermediate-day variety works well in most climate zones without requiring specific soil types
- +Low sulfur content makes processing tear-free and less irritating
- +Beautiful golden-yellow color adds visual appeal to fresh dishes
Considerations
- -Limited storage life of 2-4 months compared to storage onions that keep 6-8 months
- -Higher water content makes bulbs more susceptible to soft rot if curing conditions aren't ideal
- -Sweet flavor can become bland when cooked extensively—better for light sautéing than long braising
- -Hybrid variety means you cannot save seeds for next year's crop
- -More expensive than open-pollinated varieties due to hybrid breeding costs
Companion Plants
Plant Together
Carrots
Onions repel carrot flies while carrots help break up soil for onion bulb development
Tomatoes
Onions deter aphids, spider mites, and hornworms from tomato plants
Brassicas (Cabbage, Broccoli)
Onions repel cabbage worms, flea beetles, and other brassica pests
Lettuce
Onions provide natural pest protection while lettuce acts as a living mulch
Peppers
Onions deter aphids and other soft-bodied insects that attack pepper plants
Strawberries
Onions repel slugs and aphids that commonly damage strawberry plants
Roses
Onions help prevent black spot and aphid infestations on roses
Cucumber
Onions repel cucumber beetles and other pests while not competing for nutrients
Keep Apart
Beans
Onions can inhibit nitrogen fixation and stunt the growth of bean plants
Peas
Onions release compounds that can reduce pea plant growth and pod development
Asparagus
Both compete for similar soil nutrients and onions can inhibit asparagus spear production
Pests & Disease Resistance
Resistance
Good hybrid vigor with resistance to pink root and basal rot
Common Pests
Onion maggot, thrips, cutworms
Diseases
Downy mildew, purple blotch, neck rot