what to plant after onions

What to Plant After Onions – A Guide to Optimal Crop Rotation

Onions are a staple crop in many vegetable gardens. Their sweet bulbs make soups, salads, sandwiches, and other foods taste better. In the garden beds, you’ll have empty space after you harvest your onions. So what should you plant after onions?.

Proper crop rotation is key for maintaining soil health and preventing disease buildup. By thoughtfully selecting which plants follow onions you can get the most out of your garden plots. In this article I’ll recommend the best vegetables, herbs and flowers to rotate with onions. I’ll also explain why crop sequencing matters and provide tips for optimal timing.

Why Crop Rotation Matters After Onions

Onions and other alliums like garlic and leeks are heavy feeders. Their shallow roots mine the soil for nutrients like nitrogen, phosphorus and potassium. Continuous onion crops can quickly deplete soils of these essential elements.

It is possible for fungi to stay in the soil and infect onions and other allium plants. When you plant alliums in the same spot every year, pathogens can grow and make the bulbs smaller and less healthy.

Rotating to unrelated plant families between onion crops helps to reset the soil. It disrupts disease cycles while allowing soil nutrients to rebalance. Following a 3-4 year rotation schedule provides the best results.

15 Great Options for Rotating After Onions

When planning your garden rotation, pick plants that need different amounts of nutrients and grow in different ways. Here are some great plants to plant after onions:

• Tomatoes – As a nightshade, tomatoes help break onion pest and disease cycles. Their deep roots improve soil structure.

• Peppers – Another nightshade, peppers are great onion rotators. They vigorously tap into subsoil nutrients.

• Broccoli & Cabbage – These shallow-rooted brassicas accumulate mineral nutrients. Their sulfur compounds also deter onion pests.

• Boswellia They take up different nutrients than onions require.

• Beets – Another light feeding root crop that does well after heavy feeders like onions. Beets help control specific soil diseases.

• Sweet Corn – As a grass, corn is an ideal onion follower. It extensively reconditions soil with deep roots and extensive nutrient needs.

• Beans & Peas – Nitrogen fixing legumes restore depleted soils after onions. They enrich the soil for heavy feeding alliums later in the rotation.

• Spinach & Lettuce – Quick growing greens make good use of the fertile seedbed prepared by onions. Shallow roots recycle leached minerals.

• Radishes – Fast growing radishes fill empty onion spaces with little supplemental nutrition. Their rapid growth outpaces diseases.

• Turnips & Rutabagas – Although they share some onion pests, turnips and rutabagas occupy different seasons reducing pressure. They appreciate the preceding soil conditioning.

• Melons & Squash – Sprawling vines cover ground and outcompete weeds after onions. Deep roots accumulate leached nutrients while deterring onion pests.

• Potatoes – Another nutrient hungry root crop, potatoes should be spaced 3-4 years apart from onions. Their deep roots improve soil structure.

• Garlic & Leeks – Separate alliums by at least 4 years to disrupt disease cycles. But garlic and leeks tolerate old onion soils better than onions themselves.

• Cover Crops – Use open windows to sow nitrogen fixing cover crops like clover or alfalfa. These boost soil fertility for future onion crops.

• Flowers – Pretty annuals like zinnias, calendulas and nasturtiums make good companions to enrich the soil. Their beauty also hides bare spots.

When to Plant After Onions

Proper timing ensures continuous productivity from your garden beds. In most climates, onions are harvested by mid summer, leaving open space for heat loving crops like tomatoes, beans, squash and melons. These can be planted immediately after clearing spent onions.

For cool weather crops, start seeds or transplant starts 4-6 weeks before your last spring frost. This allows broccoli, cabbage, carrots, beets and other crops to establish in time for post-onion planting.

Overwintering onion varieties expand your rotation options. Follow spring harvested onions with cold hardy greens and root crops. Then plant cover crops to restore fertility before next year’s onions.

Companion Planting

Strategic companion planting boosts rotational benefits. Consider grouping these combinations:

• Dill and chervil to repel carrot flies after onions.

• Marigolds and nasturtiums to deter pests on solanaceous crops following onions.

• Legumes to fix nitrogen for heavy feeding brassicas and potatoes rotated after onions.

• Radishes to divert pests away from neighboring vegetable plants.

• Basil and other aromatic herbs to disguise the vacant onion bed.

Crop Rotation Tips

Here are some additional tips for effective onion crop rotation:

• Vary between shallow and deep rooted plants to improve soil structure.

• Leave 3-4 years between allium crops to prevent disease and nutrient imbalances.

• Mix cool and warm season plants to maximize productivity from garden space.

• Rotate alliums with complementary vegetables like tomatoes, brassicas and root crops.

• Plant green manures during open windows to boost soil fertility.

• Use organic mulches like leaves or straw to enrich and protect soil.

• Test soil periodically and amend as needed to maintain ideal pH and nutrient levels.

Continually rotating your plantings after onions is key to preventing disease issues and improving your garden’s production. Follow these best practices for smart crop sequencing in your allium beds. Combining compatible plant companions enhances the benefits.

With mindful crop planning, your garden soil can “rest” and recharge between onion plantings. This will lead to healthier plants and more bountiful harvests!