How To Plant Onion Set [ Full Guide ]

Onions are a kitchen staple, adding flavor and depth to a wide variety of dishes. With their versatility and relatively easy cultivation, onions are a popular choice for many home gardeners. Planting onion sets (small, dormant bulbs) is an efficient way to grow this kitchen essential. In this comprehensive guide, we will show you how to plant onion sets step by step, from gathering supplies to preparing the soil, creating rows, and ensuring proper spacing for healthy onion growth.

Before delving into the specifics of planting onion sets, it is important to understand why this method is favored by many gardeners. Onion sets are essentially young onion bulbs that were grown from seed the previous year and then dried. By using sets, as opposed to seeds, gardeners can achieve a more predictable outcome with potentially larger bulbs. Additionally, onion sets mature faster than seeds, making them an appealing option for those looking for a faster harvest.

Quick Answer: How To Plant Onion Set

Before we dive into the detailed step-by-step process, here’s a quick overview of how to plant onion sets:

  1. Gathering Supplies: You will need onion sets, a well-draining soil mix, a spade or garden fork, and compost or fertilizer.
  2. Choosing the Right Onion Sets: Select healthy, firm onion sets that are suited to your growing zone and desired onion type.
  3. Preparing the Soil: Ensure the soil is well-draining, weed-free, and enriched with organic matter.
  4. Creating Rows and Spacing: Create furrows or raised beds and space the sets according to the specific type of onion you are planting.
  5. Planting the Sets: Place the sets in the soil, ensuring they are upright and at the proper depth.
  6. Caring for the Onions: Water the sets regularly, keep the area free of weeds, and be mindful of potential pests and diseases.
  7. Harvesting: Monitor the growth of the onions and harvest them when the tops have fallen over and started to turn brown.

Gathering Supplies

Before you start planting your onion sets, it’s important to gather all the necessary supplies. Here’s what you’ll need:

  • Onion Sets: Purchase high-quality onion sets from a reputable garden center or nursery. Look for sets that are firm, free from mold or disease, and specific to the type of onion you want to grow.
  • Well-Draining Soil Mix: Onions thrive in well-draining, fertile soil. If your garden soil is heavy or prone to waterlogging, consider creating raised beds or amending the soil with organic matter to improve drainage.
  • Spade or Garden Fork: You’ll need a spade or garden fork to prepare the soil, create rows, and plant the onion sets.
  • Compost or Fertilizer: Incorporating organic matter such as compost or well-balanced fertilizer into the soil will provide the nutrients necessary for healthy onion growth.

Choosing The Right Onion Sets

Selecting the right onion sets is crucial for a successful harvest. When choosing onion sets, consider the following factors:

  • Type of Onion: There are various types of onions, including short-day, intermediate-day, and long-day varieties. Choose sets that are appropriate for your growing zone and the type of onion you want to grow. For example, if you live in a northern region, opt for long-day onion sets.
  • Size and Firmness: Look for sets that are firm and free from soft spots or signs of decay. Avoid sets that are mushy or exhibiting signs of mold.
  • Disease-Free: Inspect the sets for any signs of disease, such as mold, discoloration, or pest damage. It’s essential to start with healthy, disease-free sets to minimize potential issues during the growing season.

Preparing The Soil

Before planting your onion sets, it’s crucial to prepare the soil to provide an optimal growing environment. Follow these steps to prepare the soil for planting:

  1. Weed Removal: Clear the planting area of any weeds or unwanted vegetation. Weeds can compete with onions for nutrients and water, so it’s essential to start with a clean planting bed.
  2. Soil Enrichment: If your soil is not already rich in organic matter, incorporate compost or well-balanced fertilizer to improve fertility. Onions thrive in soil that is high in organic matter, so amending the soil will provide necessary nutrients for optimal growth.
  3. Soil Texture: Ensure that the soil is well-draining and has a loose, friable texture. Heavy, compacted soil can impede onion bulb development, so consider using raised beds or incorporating sand or organic matter to improve drainage.
  4. Soil pH: Onions prefer slightly acidic soil with a pH ranging from 6.0 to 6.8. Test the soil pH using a home testing kit, and if necessary, amend the soil to achieve the ideal pH level for onion cultivation.

Creating Rows And Spacing

Once the soil is prepared, the next step is to create rows or beds for planting the onion sets and establish proper spacing for optimal growth.

  1. Row Formation: Use a garden hoe or rake to create rows in the prepared soil. The rows should be approximately 12-18 inches apart to allow for adequate airflow and access for maintenance tasks such as weeding and watering.
  2. Raised Beds: If you prefer raised bed gardening, construct raised beds in your garden space. Ensure that the raised beds have sufficient depth to accommodate the onion sets and provide good drainage.
  3. Spacing Considerations: The spacing of onion sets will ultimately depend on the specific type of onion you are planting, as well as the desired bulb size. Typically, onion sets should be spaced 4-6 inches apart within the rows. Additionally, if you are planting multiple rows, ensure that there is ample space between the rows to facilitate easy access and proper plant development.
RELATED  How To Plant Grass Seed In Fall [ Full Guide ]

Planting The Sets

Planting onion sets is a relatively straightforward process, but it is important to ensure that the sets are planted at the correct depth and orientation. Follow these steps to properly plant your onion sets:

  1. Set Placement: Place the onion sets in the prepared soil, ensuring that they are oriented in an upright position. The tip of the sets, which is the pointed side, should face upwards, while the root side, which is often flatter, should be positioned downwards.
  2. Planting Depth: The sets should be planted at a depth of approximately 1 inch into the soil. This depth will provide stability for the sets while allowing the new foliage to emerge easily.
  3. Spacing: As mentioned earlier, space the sets 4-6 inches apart within the rows. Proper spacing allows for adequate air circulation and reduces the likelihood of fungal diseases.
  4. Covering the Sets: Gently cover the sets with soil, ensuring that they are secure and the tips are just below the soil surface. Firmly press the soil around the sets to provide stability and good soil-to-set contact.

Caring For The Onions

Once the onion sets are planted, consistent care is vital to ensure healthy growth and a successful harvest. Here are key care tips for nurturing your onion sets:

  1. Watering: Onions require consistent moisture, especially during bulb formation. Water the onion sets regularly, ensuring that the soil is evenly moist but not waterlogged. A layer of organic mulch can help retain soil moisture and suppress weed growth.
  2. Weed Management: Keep the planting area free from weeds, as they can compete with onions for nutrients and water. Regularly remove any weeds that appear near the onion sets, taking care to avoid disturbing the shallow onion roots.
  3. Fertilization: Consider a balanced, slow-release fertilizer to provide the necessary nutrients for onion growth. Apply fertilizer according to the manufacturer’s instructions, typically a few weeks after planting and again during bulb development.
  4. Pest and Disease Control: Monitor the onion plants for signs of pests such as onion thrips or diseases like onion white rot. Implement preventative measures, such as using insecticidal soap for pests and practicing crop rotation, to minimize the risk of disease.

Planting onion sets is a rewarding and relatively simple process that can yield a bountiful harvest of this kitchen staple. By selecting the right onion sets, preparing the soil, creating proper spacing, and providing consistent care, you can cultivate healthy onions in your home garden. Whether you’re a seasoned gardener or a novice, following these steps and tips will help you successfully grow and harvest delicious, homegrown onions. With the detailed guidance provided in this article, you can confidently plant onion sets and enjoy the satisfaction of growing your own fresh, flavorful onions.

Planting Depth

Onions are a staple ingredient in many recipes and are a versatile vegetable that can be grown in your backyard garden. They can be grown from seeds, but another popular method is to plant onion sets. Onion sets are small bulbs that have been partially grown from seed the previous year. They are an easier and quicker way to grow onions compared to starting from seeds.

The first step in planting onion sets is determining the planting depth. When planting onion sets, it is important to consider the size of the sets and the soil conditions.

Ideally, the onion sets should be planted 1 to 2 inches deep into the soil. If you have heavy or clay soil, it is recommended to plant them at the shallower end of the spectrum. On the other hand, if your soil is loose and well-draining, you can plant them at the deeper end of the range. This will ensure that the roots are well-established and that the plants have proper support.

To plant the onion sets, first prepare the soil by removing any weeds or debris. Using a garden fork or hoe, loosen the soil to a depth of about 6 inches. Make sure that the soil is well-draining to prevent waterlogged conditions, which can cause rotting of the onion sets.

Using your finger or a dibber, create a hole in the soil that is deep enough to accommodate the onion set. Place the onion set in the hole with the pointed side facing up and cover it gently with soil. Leave about 4 to 6 inches of space between each onion set to allow for proper growth and bulb development.

Watering Techniques

Watering is a crucial aspect of onion set planting as it helps in seed germination and promotes healthy growth. The key is to ensure that the onion sets receive a consistent supply of moisture without becoming waterlogged.

After planting the onion sets, water the soil thoroughly but gently. This helps to settle the soil around the sets and ensures good soil-to-root contact. Avoid overwatering as it can cause the sets to rot.

Once the onion sets have sprouted and started to grow, it is important to water them regularly to keep the soil evenly moist. Onions require about 1 inch of water per week, either from rainfall or irrigation. If there is not enough rainfall, you may need to water them more frequently.

RELATED  How To Plant Grape [ Full Guide ]

It is best to water the onions deeply, allowing the water to reach the root zone. Avoid wetting the foliage as it can increase the risk of diseases. To prevent water evaporation and maintain soil moisture, consider using mulch around the onion plants.

Fertilizing Tips

Proper fertilization is important for the healthy growth and development of onion sets. Before planting, it is recommended to prepare the soil by incorporating organic matter such as compost or well-rotted manure. This will provide a good foundation for the onion sets to grow.

Onions are heavy feeders, so they benefit from regular fertilization throughout their growth. Approximately 4 weeks after planting the onion sets, you can start applying a balanced fertilizer with an equal ratio of nitrogen (N), phosphorous (P), and potassium (K). Look for a fertilizer with an NPK ratio of 10-10-10 or a similar ratio.

To apply the fertilizer, scatter it around the base of the onion plants, keeping it about 3 to 4 inches away from the stems. Avoid applying the fertilizer directly on the foliage as it can burn the plants.

After applying the fertilizer, water the soil thoroughly to allow the nutrients to penetrate into the root zone. Repeat the fertilizer application every 4 to 6 weeks throughout the growing season. This will provide a continuous supply of nutrients to the onion plants and promote healthy growth.

Mulching Methods

Mulching is a beneficial practice for onion sets as it helps conserve moisture, suppresses weed growth, and moderates soil temperature. Mulch also acts as a protective layer, preventing damage from heavy rain and reducing soil erosion.

After planting the onion sets and watering them, apply a layer of organic mulch around the plants. Suitable mulch materials for onions include straw, chopped leaves, or grass clippings. Apply the mulch to a thickness of about 2 to 3 inches, making sure to keep it away from the stems to prevent rotting.

Mulching not only helps retain moisture but also suppresses weed growth. Weeds compete with onions for nutrients and water, so it is important to keep them under control. The mulch barriers created by organic materials smother weeds and prevent them from germinating and growing.

In addition to organic mulch, you can also use black plastic mulch to warm the soil and promote early growth. The black plastic absorbs heat from the sun and helps retain soil moisture. However, it is important to ensure proper drainage when using plastic mulch to prevent waterlogged conditions.

Controlling Weeds

Weed control is essential for the successful growth of onion sets. Weeds compete with onions for essential resources such as water, sunlight, and nutrients. They can slow down onion growth and reduce bulb development if not properly controlled.

The first step in weed control is to prepare the soil before planting by removing any existing weeds or grass. This can be done by hand-pulling or using a garden hoe or cultivator. Be thorough in removing all weed roots to prevent regrowth.

After planting the onion sets and applying mulch, inspect the area regularly for any new weed growth. Remove any weeds that emerge by hand-pulling or using a garden hoe. Be careful not to disturb the onion plants or their roots during the weeding process.

To further minimize weed growth, consider utilizing weed suppressants such as landscape fabric or plastic mulch. These materials can be laid down before planting the onion sets to create a barrier that prevents weed seeds from germinating.

Another effective method for controlling weeds is to apply a pre-emergent herbicide before planting the onion sets. This type of herbicide inhibits weed seed germination and can provide long-lasting weed control. However, it is important to carefully read and follow the instructions on the herbicide label to ensure safe and effective use.

Planting onion sets is a straightforward and rewarding process. By following the steps outlined in this article, including determining the planting depth, employing proper watering techniques, applying fertilizers, using mulching methods, and controlling weeds, you can successfully grow healthy and flavorful onions in your garden. Enjoy the satisfaction of harvesting your own homegrown onions and adding them to your favorite recipes.

Protecting Onion Sets From Pests And Diseases

Onion sets are available in many varieties, colors, and sizes. They are sold in bags at garden centers, nurseries, and online. Onion sets can be planted in the fall or spring, depending on the variety and location. Onion sets are usually planted in rows with about six inches between them. They should be planted about an inch deep with the pointed end up.

Before planting onion sets, you must first prepare the soil. Onion plants require soil with good drainage and plenty of nutrients. If the soil in your garden is poor, you may need to amend it with compost, manure, or other organic matter. You should also test the soil’s pH level and adjust it if necessary. The pH level of the soil should be between 6.0 and 7.0, as onions prefer slightly acidic soil.

RELATED  How To Plant Bonsai Tree [ Full Guide ]

Onions are vulnerable to a few pests and diseases, which can damage the plants and reduce their yield. One of the most common pests that attacks onion plants is the onion maggot. These small, white maggots feed on the roots and bulbs of onion plants, causing them to rot and die. To prevent onion maggots from attacking your plants, you should cover the soil around the plants with a layer of mulch or other protective barrier.

Another common pest that can damage onion plants is the thrips. These tiny insects feed on the leaves of onion plants, causing them to turn yellow and wilt. To prevent thrips from attacking your plants, you should keep the plants well-watered and avoid overcrowding them.

Onions can also fall prey to fungal diseases such as onion rot. If you notice that your onion plants are wilting or turning brown at the base, they may have onion rot. To prevent onion rot from attacking your plants, you should avoid watering them too much and keep them well-ventilated.

Harvesting And Curing

Onions can be harvested when the leaves begin to turn yellow and fall over. This usually occurs about four months after planting. To harvest onions, gently pull them out of the soil by the stems and lay them on the ground to dry. It is important to avoid damaging the bulbs when pulling them out of the soil.

After harvesting, onions should be cured to prolong their shelf life. Curing involves drying the onions in a warm, dry, and well-ventilated area for several weeks. During this time, the outer layer of the onion will dry and harden, protecting the bulb from damage. Once the onions are fully cured, the stems can be trimmed to about an inch long, and the roots can be removed.

Storing Onions

Onions can be stored for several months if they are kept dry and cool. Once the onions are fully cured, they should be stored in a dry, cool, and well-ventilated area. You can store onions in mesh bags, baskets, or crates, and avoid storing them in airtight containers.

Troubleshooting Common Problems

Sometimes onion plants can experience problems that result in a low yield or poor quality onions. Below are some common problems and solutions.

Low Yield

If your onion plants are not producing many bulbs, they may be overcrowded. Onion plants should be planted about six inches apart to allow for proper growth. If the soil is too dry, onion plants may also produce a low yield. Be sure to water your onion plants regularly to keep the soil moist but not waterlogged.

Small Bulbs

If your onion plants are producing small bulbs, they may be lacking nutrients. Onion plants require soil with plenty of nitrogen, phosphorus, and potassium. Be sure to amend the soil with compost or other organic matter to provide the necessary nutrients. Onion plants also require soil with good drainage, as standing water can prevent proper bulb formation.

Soft Or Rotten Bulbs

If your onion plants’ bulbs are soft or rotten, they may have been infected with a fungal disease such as onion rot. To prevent fungal diseases, be sure to plant onion sets in well-drained soil and avoid watering them too much. You can also use a fungicide to treat infected plants.


Growing onions from sets is a rewarding and enjoyable experience. With proper preparation, care, and maintenance, you can harvest a bountiful crop of delicious and flavorful onions. Remember to protect your onion sets from pests and diseases, harvest and cure them properly, store them in the correct conditions, and troubleshoot common problems. Enjoy your fresh, homegrown onions in all your favorite recipes!


What Type Of Soil Is Best For Planting Onion Sets?

Onion sets thrive in well-drained, loose soil that is rich in organic matter. Make sure to avoid clayey or compacted soil.

How Do I Prepare The Planting Area For Onion Sets?

Before planting, loosen the soil to a depth of 8-10 inches and mix in a layer of compost or well-rotted manure. This will provide the necessary nutrients for the onions to grow.

When Is The Best Time To Plant Onion Sets?

Onion sets are typically planted in the early spring, once the soil can be worked and the danger of frost has passed. However, they can also be planted in the fall for an early summer harvest.

How Deep Should I Plant Onion Sets?

Onion sets should be planted 1-2 inches deep with the pointed end facing up. If you are planting in rows, make sure to space the sets 4-6 inches apart.

How Often Should I Water Onion Sets After Planting?

Onions have shallow roots, so it is important to keep the soil consistently moist but not waterlogged. Water deeply once a week, and increase the frequency during hot, dry weather. Avoid overhead watering, as this can increase the risk of disease.