How to Grow Delicious Onions in Ohio – A Complete Guide

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Onions are a versatile vegetable that add tons of flavor to foods. If you live in Ohio you can successfully grow onions in your own garden with proper planning and care. Follow this complete guide for tips on selecting onion varieties when to plant, growing from seeds or sets, and caring for your crop throughout the season. You’ll be harvesting armloads of juicy, homegrown onions in no time!

Choosing the Best Onion Varieties for Ohio

Ohio’s climate is well-suited for growing long-day onion varieties. Long-day onions require 14-16 hours of daylight to form bulbs, making them a great match for Ohio’s long summer daylight hours.

Some top long-day onion varieties to try include:

  • Copra – Reliable variety that stores well. Produces large, yellow onions.

  • Candy – Super sweet onions perfect for raw eating.

  • Super Star – Hybrid with excellent disease resistance. White skin and mild flavor.

  • Walla Walla – Sweet Spanish type good for short-term storage.

  • Ailsa Craig – Large, mild onions good for slicing raw.

  • Red Wing – Purplish-red skin and mild taste. Stores 3-6 months.

Consult seed catalogs or local nurseries to find even more long-day varieties adapted to Ohio’s growing conditions.

When to Plant Onions in Ohio

You can start onions in Ohio from seeds indoors or plant onion sets directly in the garden:

  • Seeds: Start seeds indoors 10-12 weeks before the last spring frost. Transplant seedlings outside 4 weeks before the last frost.

  • Sets: Plant onion sets outdoors 4-6 weeks before the average last frost date.

The best time to plant onions outdoors in Ohio is mid-March through mid-April. Onion seeds and sets should go in the ground as soon as it can be worked in early spring.

Growing Onions from Seeds

Starting onions from seeds takes more time and care, but gives you more variety options. Here’s how:

  • Sow seeds 1⁄4 inch deep indoors in trays 10-12 weeks before transplanting. Use a seed starting mix.

  • Keep soil moist and grow seedlings near a sunny window or under grow lights.

  • Transplant onion seedlings into the garden 4 weeks before the last spring frost.

  • Space transplants 4-6 inches apart in rows 12-18 inches apart. Set them at the same depth as in trays.

  • Water transplants well and protect from frost with covers if needed.

Planting Onion Sets

For a faster harvest, onion sets are a great option. Follow these tips:

  • Choose small, firm onion sets without signs of sprouting or mold.

  • Plant sets 1-2 inches deep and 2-3 inches apart in rows 12 inches apart.

  • Push sets gently into soft garden soil in early spring 4-6 weeks before the last frost.

  • Water thoroughly after planting sets. Cover with mulch to retain moisture.

Growing Onions from Seeds vs. Sets

Both seed and set onions have pros and cons:

  • Seeds provide more variety options but take longer (4 months start to harvest).

  • Sets let you skip starting indoors and give earlier harvests (1-2 months).

  • Seeds are cheaper, while sets are more convenient.

  • Sets sometimes bolt prematurely if subjected to cold weather.

Choose the method that best fits your needs and schedule!

Caring for Onions as They Grow

Give your growing onions attentive care for healthy, robust bulbs:

  • Water 1-2 inches per week. Avoid both overwatering and drought.

  • Weed meticulously to prevent competition for nutrients and water.

  • Side-dress with nitrogen fertilizer monthly during main growth.

  • Hill soil up against bulbs as they enlarge to cover and stabilize bases.

  • Control pests like onion maggots, cutworms, and thrips organically.

  • Harvest green onions for salads once tops are 6 inches tall.

Consistent watering and quick weeding are vital to grow full-sized, picture-perfect onions.

How to Tell When Onions Are Ready to Harvest

Onions take 3-5 months to mature depending on variety. Watch for these signs bulbs are ready for harvest:

  • Tops soften and fall over.
  • Necks shrink and soften.
  • Skin takes on mature color – yellow, red or white.
  • When lifted, small roots come off bulbs easily.

Stop watering once 50% of tops fall over so necks cure well.

Harvesting and Storing Onions

Gather a bountiful harvest of fresh onions for months of enjoyment:

  • Carefully lift bulbs with a garden fork, avoiding cuts or bruising.

  • Allow onions to dry for 1-2 weeks laid out in a warm, well-ventilated spot.

  • Brush off loose dirt but don’t wash yet. Clean outer scales will help storage.

  • Trim off foliage, leaving 1-2 inches of stem. Take care not to cut into the bulb.

  • Cure onions in a dark, dry area with plenty of air circulation for 2-3 weeks.

  • Store fully cured bulbs in mesh bags or crates in a cool (40-50°F), very dry spot.

Follow proper harvesting steps for maximum onion storage of 3-6 months or more.

Enjoying the Onion Harvest

Homegrown onions are incredibly versatile in the kitchen. Here are some ways to put your harvest to good use:

  • Chop pungent yellow, white or red onions to flavor countless savory dishes.

  • Make caramelized onions, jam, relish, or pickled onions.

  • Grill large onion slices as burger toppings or kebabs.

  • Fry up rings of sweet Vidalia-type onions for appetizers or garnishes.

  • Use milder varieties raw in salads, salsas and sandwiches.

With the right care, Ohio gardeners can grow a year’s supply of onions that are far superior to store-bought. Now go enjoy the fruits of your labor!

When armed with the proper knowledge on selecting varieties, planting methods, and care, growing a bountiful crop of onions in Ohio is very achievable. Follow the tips above on when to sow, fertilizing, watering, pest control, and harvesting for your best onion harvest yet. With tasty homegrown onions, you’ll bring huge flavor to soups, stews, sandwiches and more all season long.

Should I Grow Onions from Seeds or Sets?

We like planting onion sets instead of starting them from seeds because they grow faster and are easier to plant.

  • Onion sets are small onions that are ready to eat in 14 weeks. They are more likely to grow than direct-sown seeds or transplants and can handle light freezes. You can buy onion sets at gardening stores. They look like small bulbs and grow into full-size bulbs when they’re ready. Pick onion sets with bulbs that are 3/4 of an inch in diameter; bigger ones tend to grow stiff necks and seeds.
  • Of course, you can start onions from seeds, and in colder places (Zone 5 and below), you may even need to. To grow onions from seeds, the soil needs to be at least 50°F. This means that the onions should be started indoors about 6 weeks before they are moved to the garden. If you’d like to try this method, read our guide on how to grow onions from seeds.

Practice crop rotation with onions. Don’t plant them in the same spot every year, because that can help diseases that hurt the crop spread. Learn more about crop rotation. Read Next.

Select a location with full sun, where other plants won’t shade your onions. The more energy they can get from the sunlight, the larger their bulbs can grow. Mix aged manure or compost into the soil in the fall or early spring to improve texture. Ensure there are no rocks or debris. Soil needs to be well-draining and loose; compacted soil affects bulb development.

When to Plant Onions

  • In the spring, plant onion sets outside as soon as the ground can be worked. This is usually in late March or early April, when it won’t be colder than 28°F (-2°C).
  • Early in the spring, plant onion seeds indoors and let them grow for about six weeks. Then, when the soil is at least 50°F, move them outside.
  • If you plant onions in the fall, they need at least 4 to 6 weeks of warm weather to get established in the ground. The onions will stay dormant during the cool months. When the weather and soil warm up again in early spring, they come back to life.

Starting Onions and Leeks From Seed | Winter Sowing | Central Ohio Zone 6A


What is the trick to growing onions?

Grow them in a sunny spot that has fertile, well-drained soil with a pH of 6.0 to 6.8. Improve your native soil by mixing in several inches of aged compost or other rich organic matter. Onions aren’t great at taking up water, so it’s important to keep soil moist so their shallow roots can drink up.

What type of onions grow best in Ohio?

Suggested Varieties for Ohio Gardens Dry (storage) – Ebenezer, Yellow Globe strains, Elite, Stuttgarter (from sets).

How long do onions take to grow?

How long do onions take to grow? Onions require 90-100 days to mature from seed, which is around four months. From sets, onions are ready to harvest after around 80 days, or just under three months.

How many onions grow from one bulb?

If you plant the whole cut bottom as one piece, you may get more than one new onion but they will likely be crowded together and small. The number of plants a single onion can grow will vary from 1-6, the onion pictured above can be divided into two.

When should you plant onions in Ohio?

The best rule of (green) thumb is to plant onion seedlings into the ground after the danger of frost has passed. This is usually by mid-April, but it could be as late as mid-May. In Ohio, here are some average frost dates for planting onions and other garden favorites. Onions grow in direct sunlight.

What kind of soil do onions grow in?

Onion grows best in an area that has full sun, loose, well-drained, fertile, sandy-loam to silt-loam soils soil with plenty of organic matter. Onions are easily affected by high acid soils and prefer soil pH between 6.0 and 6.8. Avoid heavy clay soils as they retain water longer after rains and irrigation.

How do you grow a green onion in a pot?

Here’s how to do it: Fill a pot with potting soil and make a hole in the middle about the onion’s depth and width. Place the onion in the hole and cover with soil. Water and put the pot in a sunny spot. Harvest the green sprouts as needed for cooking. If you get a sprout with a flower, wait until the flower goes to seed.

How do onions grow?

Onions are started by seeds, sets, and transplants. Garden stores offer sets for transplanting—arguably the easiest way to grow onions. Sets, which are onion bulbs previously started from seeds, are small and firm. Onions grow in soil temperatures of 36 degrees Fahrenheit or higher (they thrive in climates where the temps are 50 F. or more).

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