Onion Transplants for Sale: When to Buy & How to Choose

Onion transplants are young onion seedlings ready for planting, typically available for purchase from late winter through early spring. The best time to buy depends on your USDA hardiness zone, with northern growers ordering in February-March and southern growers in November-January. Quality transplants should be pencil-thick, disease-free, and properly stored at 32-35°F until planting.

Discover exactly when to buy onion transplants for your region, how to select the healthiest plants, and what to expect for successful harvests. This guide cuts through the confusion with science-backed timing recommendations, visual quality indicators, and practical planting strategies used by experienced gardeners.

Why Choose Onion Transplants Over Seeds

Onion transplants give home gardeners a significant advantage over starting from seeds. According to the Penn State Extension, transplants typically yield 30-50% larger bulbs because they've already overcome the critical germination phase under controlled conditions. The University of Georgia's agricultural research shows transplants mature 2-3 weeks faster than seed-started plants, crucial for regions with shorter growing seasons.

"Transplants eliminate the guesswork of seed germination rates and early-season pest vulnerability," explains Dr. Robert Westerfield, vegetable specialist at UGA. "For most home gardeners, especially beginners, transplants dramatically increase success rates."

Understanding Onion Transplant Types and Varieties

Not all onion transplants are created equal. Your selection should match your geographic location and culinary preferences. Day-length requirements determine which varieties will properly form bulbs in your region:

Variety Type	Best For Zones	Harvest Time	Storage Life	Flavor Profile
Long-Day Onions	3-5 (Northern)	July-August	6-8 months	Strong, pungent
Intermediate-Day	5-7 (Midwest)	June-July	4-6 months	Balanced
Short-Day Onions	7-10 (Southern)	May-June	2-4 months	Sweet, mild

When to Purchase Onion Transplants by Region

Timing your purchase correctly ensures you receive vigorous plants ready for your soil conditions. The USDA Plant Hardiness Zone Map provides the framework, but microclimates matter:

• Northern Zones (3-5): Order in February, plant as soon as soil can be worked (late March-April)
• Midwest Zones (5-7): Order in March, plant early to mid-April
• Southern Zones (7-10): Order in November-January, plant December-February

"Many gardeners make the mistake of waiting too long to order northern varieties," notes the University of Minnesota Extension. "Reputable suppliers often sell out by early March because commercial growers secure the majority of transplants first."

How to Identify Quality Onion Transplants

Not all available transplants deliver equal results. Use these professional selection criteria before purchasing:

Visual Quality Indicators

• Size: Ideal transplants measure 1/8 to 1/4 inch in diameter - pencil-thick
• Color: Vibrant green tops without yellowing or browning
• Roots: White, fibrous roots (avoid brown, mushy roots)
• Condition: No signs of mold, disease, or insect damage

Storage and Handling Requirements

Proper storage before planting significantly impacts survival rates. Research from Cornell University shows transplants stored above 40°F for more than 48 hours experience 25% higher transplant shock. The Oregon State University Extension recommends:

• Refrigerate upon arrival at 32-35°F
• Keep bundled plants moist but not wet
• Plant within 7-10 days of receipt
• Never allow roots to dry out before planting

What to Expect for Pricing and Quantities

Understanding typical pricing structures helps avoid overpaying while ensuring quality. Market data from agricultural suppliers shows consistent patterns:

• 10-25 plants: $3-6 (ideal for small gardens)
• 50-100 plants: $0.15-0.25 per plant
• 250+ plants: $0.10-0.15 per plant (wholesale rates)

Be cautious of prices significantly below these ranges, which often indicate older stock or poor quality. Reputable suppliers typically provide variety specifications, planting instructions, and germination guarantees.

Planting and Care for Maximum Yield

Proper planting technique determines your harvest success more than any other factor. Follow these research-backed methods:

1. Soil preparation: Amend with 2-3 inches of compost, ensuring pH 6.0-6.8
2. Planting depth: Set transplants so only the very top remains visible
3. Spacing: 4-6 inches between plants in rows 12-18 inches apart
4. Watering: 1 inch per week, consistent moisture critical during bulb formation
5. Fertilizing: Side-dress with nitrogen when tops reach 6 inches

The University of Wisconsin Extension emphasizes that inconsistent watering during bulb formation causes splitting and reduces storage life. "Onions need steady moisture - drought followed by heavy rain creates onion doubles and reduces quality," states their vegetable production guide.

Avoiding Common Onion Transplant Mistakes

Even experienced gardeners make these preventable errors that reduce yields:

• Planting too deep: Buried growth plates prevent proper bulb development
• Ignoring day-length requirements: Wrong varieties won't bulb properly
• Over-fertilizing with nitrogen: Creates excessive top growth at bulb expense
• Planting too early: Frost damage stunts growth and invites disease
• Crowding plants: Reduces bulb size and increases disease risk

"The single biggest mistake I see is gardeners trying to save transplants that arrived in poor condition," says agricultural extension agent Martha Smith. "It's better to request replacements than struggle with weak plants that never recover."

When Onion Transplants Aren't Your Best Option

While transplants work well for most home gardeners, certain situations warrant alternative approaches:

• Very short seasons: Consider starting seeds indoors 8-10 weeks before last frost
• Unique heirloom varieties: Many specialty onions only available as seeds
• Large-scale planting: Direct seeding more economical for 100+ plants
• Specific disease resistance: Some resistant varieties only available as seeds

For gardeners in zones 8-10, the University of Florida Extension recommends short-day varieties like 'Texas Super Sweet' or 'Granex' for best results, typically planted from December through February.

When is the best time to order onion transplants?

Order timing depends on your USDA hardiness zone. Northern gardeners (zones 3-5) should order in February for spring planting. Midwest gardeners (zones 5-7) should order in March. Southern gardeners (zones 7-10) need to order in November-January for winter planting. Ordering early is crucial as quality suppliers often sell out before peak season.

How can I tell if onion transplants are healthy?

Healthy onion transplants should be pencil-thick (1/8 to 1/4 inch in diameter) with vibrant green tops and white, fibrous roots. Avoid plants with yellowing leaves, brown or mushy roots, or signs of mold. The ideal storage temperature before planting is 32-35°F, and they should be planted within 7-10 days of receipt for best results.

What's the difference between long-day and short-day onion varieties?

Long-day onions (best for zones 3-5) require 14-16 hours of daylight to form bulbs and are typically pungent with long storage life. Short-day onions (zones 7-10) form bulbs with 10-12 hours of daylight, are sweeter, and have shorter storage life. Intermediate-day varieties work in zones 5-7 with 12-14 hours of daylight required. Choosing the wrong type for your region results in poor bulb formation.

How many onion transplants do I need per person?

Most home gardeners plant 20-30 onion transplants per person for fresh use and storage. This typically yields 15-25 pounds of onions per 10 square feet of garden space. If you consume onions frequently or want ample storage onions, consider 40-50 plants per person. Remember that about 20% of plants may not survive transplanting or develop properly.

Can I grow onions from seed instead of using transplants?

Yes, you can grow onions from seed, but it requires 8-10 weeks of indoor growing before transplanting outdoors. Seeds offer more variety options but have lower success rates for beginners. Transplants give you a 3-4 week head start and generally produce larger, more uniform bulbs. Direct seeding works best in mild winter climates or for large plantings where transplanting would be too labor-intensive.