How Deep to Plant Candy Onions for the Best Harvest

Candy onions are a sweet hybrid variety that makes a delicious addition to any garden. Getting the planting depth right is key to growing big, healthy candy onions In this comprehensive guide, we’ll look at the ideal planting depth for candy onion sets, seeds, and seedlings along with tips for preparing the soil, proper spacing, and more

What are Candy Onions?

Candy onions are a hybrid cross between common onions and sweet onions. They are sweeter than regular onions but not quite as sweet as varieties like Vidalia or Walla Walla. The bulbs grow up to 4 inches wide with a globular shape. The skins are yellowish-white.

Compared to standard onion varieties candy onions offer these advantages

• Higher resistance to diseases like downy mildew and botrytis
• Stronger, more vigorous roots
• Ability to grow very large if given adequate space
• Mild yet crisp flavor that’s perfect for raw uses

Candy onions take around 100 days to mature and can be harvested throughout the summer in most regions. They store for 1-3 months which is less than regular storage onions. But their sweet taste and large potential size makes them popular among home gardeners.

When to Plant Candy Onions

Candy onions grow best as a cool season crop The ideal planting window is early to mid spring Here are the recommended planting dates

• Spring planting: March – May
• Fall planting: August – September (overwintering)

Aim to plant candy onion sets, seeds, or transplants 4-6 weeks before the last expected frost in your area. Onions need soil temperatures of at least 55°F to germinate and actively grow.

Planting in early spring allows the onions to size up through the cool weather of spring and early summer. Temperatures above 80°F cause the bulbs to mature too quickly and this results in smaller onions.

Some gardeners also plant candy onions in late summer or fall to overwinter them. This can work in climates with milder winters. Heavy mulch helps protect the plants through cold periods so they resume growth in spring.

How Deep to Plant Candy Onion Sets

Onion sets are miniature bulbs that let you skip the seedling stage. Candy onion sets should be planted 2-3 inches deep spaced 4 inches apart in all directions. Deeper planting prevents the sets from dislodging as they begin growing. It also protects them from cold weather and drying out.

Follow these tips when planting candy onion sets:

• Prepare soil in advance by mixing in compost and balanced fertilizer
• Use a dibble stick or trowel to make holes 2-3 inches deep
• Drop one onion set into each hole and cover with soil
• Water thoroughly after planting
• Consider mulching around sets to retain moisture

Onion sets drain energy stored in the bulb to produce foliage and roots. Therefore, they yield smaller onions compared to plants grown from seeds. However, sets are extremely easy to plant. So they are a good option for beginner gardeners.

How Deep to Plant Candy Onion Seeds

When growing candy onions from seeds, the planting depth should be 1⁄4 – 1⁄2 inch. Seeds planted too deep may rot before they can emerge. Shallow planting exposes the seeds to light which is needed for germination.

Follow these tips when direct sowing candy onion seeds:

• Prepare seed beds in advance by mixing in compost
• Rake the soil smooth and remove any rocks or debris
• Use a hoe handle or stick to make 1⁄4 inch deep furrows 12-16 inches apart
• Sprinkle seeds thinly along the furrows and cover them lightly with soil
• Water gently to moisten the soil without displacing seeds
• Consider placing floating row covers to retain moisture and heat
• Thin seedlings to 2 inches apart once they sprout

Onion seeds can take up to 2 weeks to germinate depending on soil temperature. Keep the beds consistently moist during this time. Thinning is important to prevent overcrowding and allow the bulbs adequate space to enlarge.

How Deep to Plant Candy Onion Transplants

The third option for planting candy onions is using transplants. Transplants are seedlings that were started indoors and grown for 4-6 weeks before planting outside. When transplanting onions, the general planting depth is the same as for sets – 2 to 3 inches deep.

Follow these tips when transplanting candy onion seedlings:

• Harden off transplants for 7-10 days before transplanting outside
• Prepare transplant beds by mixing in aged compost or manure
• Water transplants thoroughly a few hours before transplanting
• Use a trowel to dig holes 2-3 inches deep and 12+ inches apart
• Carefully place one seedling in each hole and fill around stem with soil
• Firm the soil gently and water immediately after planting
• Consider using transplant fertilizer to reduce shock

The main advantage of transplanting onions is earlier maturity since the seedlings get a head start indoors. Just be sure to harden off the seedlings properly before exposing them to outdoor conditions. Transplant on a calm, cloudy day if possible.

Soil Preparation for Candy Onions

Preparing the soil in advance leads to healthier, more productive candy onion plants. Onions need nutrient-rich soil that drains well. Here are some tips:

• Choose a site with full sun exposure (at least 6 hours per day)
• Test the soil pH and amend with lime if needed to reach a neutral pH
• Mix in 2-4 inches of aged compost or well-rotted manure
• Add a balanced organic fertilizer according to package directions
• Create raised planting beds if drainage is poor
• Remove any weeds which compete for water and nutrients

Soil preparation can be done in fall or early spring before planting. Onions thrive when given fertile, loose soil. Avoid over-fertilizing with nitrogen which causes excessive leaf growth rather than bulb enlargement.

Proper Spacing for Candy Onions

Whether planting onion sets, seeds, or transplants, be sure to space them appropriately to allow for full bulbing. Here are the recommended spacing guidelines:

• Sets: Space 4 inches apart in rows 12-16 inches apart
• Seeds: Sow seeds 2 inches apart; thin to 3-4 inches apart in rows 12-16 inches apart
• Transplants: Space 4-6 inches apart in rows 12-16 inches apart

Wider spacing produces larger bulbs. But don’t space too far apart or weeds will take over. Closer spacing results in smaller onions. Adjust spacing depending on your desired onion size.

Harvesting Mature Candy Onions

Candy onions reach maturity around 100 days after planting. Here’s how to identify when they are ready to harvest:

• Tops fall over and turn yellow or brown
• Skins take on a papery texture
• Cutting into a bulb reveals solid white flesh
• 70-90% of the tops have fallen over
• A few outer skins can be removed easily

Use care when harvesting. Try not to bruise the bulbs as this causes storage issues. Pull green tops rather than the bulbs to lift plants. Cure bulbs for 1-2 weeks in a warm, dry spot before storage.

Storing Candy Onions Properly

Candy onions generally won’t last as long in storage compared to other onion varieties. Still, proper curing and storage conditions can help extend their shelf life to 2-3 months. Ideal storage guidelines include:

• Cure bulbs for 1-2 weeks immediately after harvest
• Store cured bulbs in a cool (32-40°F), dry location
• Use slatted crates, nets bags, or trays to allow air circulation
• Avoid exposure to sunlight which causes sprouting
• Check bulbs regularly and remove any rotting ones

Well-cured candy onions keep for a few months in the right conditions. But their incredibly sweet flavor and juicy crunch is best enjoyed fresh!

Growing Candy Onions in Containers

Don’t have space for a garden? Candy onions can also be grown in containers. Use these tips:

• Select a pot at least 12 inches wide and deep
• Use potting mix enriched with compost or manure
• Plant onion sets or transplants; seeds are harder in containers
• Space plants 4-6 inches apart in all directions
• Place pot in full sun – at least 6 hours per day
• Water when soil dries out; provide 1-2 inches per week
• Apply a balanced liquid fertilizer every 2-3 weeks

A 5 gallon bucket can accommodate 4-5 candy onion plants. Make sure the container has drainage holes on the bottom. Onions are sensitive to overwatering.

Common Problems When Planting Candy Onions

Here are some potential issues and how to resolve them:

• Seeds fail to sprout: Ensure soil moisture is consistent. Replant if no sprouts after 2 weeks.

• Leggy seedlings: Give seedlings more sunlight or use a grow light. Legginess indicates not enough light.

• Tops fall over too early: Onions planted too densely won’t bulb properly before tops fall. Allow adequate spacing.

• Small bulbs: Insufficient nutrients, overcrowding, or too much nitrogen can limit bulb size. Fertilize properly and space plants.

• Rot during storage: Harvest onions when fully mature and cure for 1-2 weeks. Rot occurs if bulbs weren’t dried properly after harvest.

Key Takeaways on Planting Depth for Candy Onions

• Onion sets should be planted 2-3 inches deep spaced 4 inches apart.
• Seeds do best planted just 1⁄4 – 1⁄2 inch deep. Thin seedlings to 2-4 inches.
• Transplants should be planted 2-3 inches deep and 4-6 inches apart.
• Prepare soil with compost and balanced fertilizer before planting.
• Allow for adequate spacing between plants for full bulbing.
• Harvest when tops fall over and skins take on papery texture.

Getting the planting depth and spacing right enables candy onions to grow their absolute biggest. Monitor soil moisture and fertility all season. Then enjoy the sweet oniony flavor of candy onions!