When to Plant Onions in Michigan? (Best Time)

Written by

William Golder


Dorian Goodwin

when to plant onions in michigan

Onions are versatile vegetables with a wide range of culinary uses, making them a staple ingredient in many recipes worldwide. But when striving for success in growing onions in Michigan, timing is everything.

An ideal time for onion planting is during early Spring, in 15th March to 20th April, or early Fall, around 10th September.

By carefully considering the timing of when to plant onions in Michigan, you can maximize your chances of growing robust, and flavorful onions, ensuring a successful and abundant harvest!

The Best Time to Plant Onions in Michigan

We must understand that knowing the optimal onion planting season is crucial for you to be able to achieve a bountiful onion harvest. Michigan’s climate is known to have cold winters and temperate summers, so this requires strategic planning.

Onions are considered a cool-season crop so it is ideal to plant onion bulbs during early spring in late March ofr April or fall in September.

If you plan to sow onion seeds, you must do so in January or February and then plant them out in April or May.

1. Early Spring Planting


Planting them in the early spring is usually recommended since the soil has thawed and soil temperatures consistently reach around 50°F.

But if you are going to plant them indoors, it is best to start six weeks before transplanting them outdoors to the ground. We suggest you plant onion seedings indoors from 25th January – 25th February to transplant them just in time for the warm soil in April and May. 

For outdoor planting, you can start right in early spring, around March.

2. Fall Planting


When planting onions in the fall, they require adequately warm temperatures for at least 4-6 weeks just so that they can establish themselves in the ground entirely. As the winter season approaches, their growing time comes to a halt and starts again in early spring.

3. Planting Onions Indoors


Due to Michigan’s short growing season, it is advisable to plant onion seedlings inside at home so that they can have a kick-start as they mature and establish themselves before the heat of summer.

This must be done in 8-10 weeks before the last frost date.

Michigan’s Last and First Frost Dates

The moment that you start to consider frost dates, you are taking the step to make informed decisions to determine the time to start planting or when is a safe season for transplantation. To help, here are the frost dates noted in Michigan:

  Last Frost Dates First Frost Dates
North Michigan May 16 to June 30 September 1 to September 30
South Michigan May 1 to May 15 October 1 to October 15

Getting to Know Onion Varieties


Another important factor to consider is knowing the best onions to grow for that season in Michigan. Each would require specific temperatures or daylight durations.

There are three varieties:

  1. Short day onion
  2. Intermediate-day onion or day-neutral onions
  3. Long day onion

The time you plant your onions greatly affects their size and the date they will be ready for harvesting. With that, you must make sure that the area you are placing them has enough day length in the correct hours depending on the variety.

  1. Short-day onions would need 10 to 12 hours of daylight in order to grow their bulbs. If you have this variety, they are best planted in Southern areas. They are highly recommended for immediate usage and are characterized by their sweetness.
  2. For intermediate-day onions, otherwise known as day-neutral onions, would need much longer hours. 12 to 14 daylight hours are enough for them, and planting them in Middle areas is encouraged for their growth.
  3. Long-day onions need the longest of hours, which is 14 to 16 hours of sunlight. It is ideal for planting them in Northern areas. Short-day onions are less sweet than short-day onions, but they are great for storage.

Michigan itself is a great place for planting onions. Here are a few of the best Michigan onion varieties that are suitable for growing in their climate:

Candy Onions Walla Walla Onions Red Burgundy Onions Sweet Spanish Onions Yellow Spanish Onions
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6 Tips for Successful Onion Planting in Michigan

1. Begin with Quality Sets or Transplants


It is the dream of many to start a worry-free journey of planting. While journeys do come with challenges, there are always ways to ensure a great start and to reduce any risks of disasters.

To do so, you must utilize healthy and disease-free onion sets or transplants before beginning your onion planting journey. You must also make sure to obtain them from reputable and trustworthy sources.

2. Soil Preparation for Planting

The quality and condition of the soil are factors one should not ignore. Well-drained, moist, and fertile soil rich in organic matter with a pH between 6.0 and 7.0 are much preferred for onions.

Onions are also quite versatile so even if they prefer sandy and loam soil types, they are still capable of growing in clay and muck soils as long as the conditions for their development are met.

3. Sufficient Spacing and Depth


Onions would need enough space to be able to grow to their full potential.

You must make sure to plant onion sets 2 to 6 inches apart and for onion transplants, it is recommended to give them a 4 to 5 inches distance and their rows 12 to 18 inches away from another.

The depth that you bury them also matters a great deal.

Onion sets and transplants must be buried 1 to 2 inches deep as gently as possible while pushing them into the soil. When setting the bulbs, remember to let their pointy ends face up.

Note: Burying your onions deeper than 2 inches can affect their growth and the development of their bulbs.

4. Adequate Watering

Moisture is one of the life forces of onions. You must make sure that it is retained all throughout its growing periods. It is recommended to water them regularly especially when there is a drought or dry season.

An inch of water every week, even with rainfall, is essential so they are able to grow large bulbs. You may make use of muck soils in order to help retain their moisture.

5. Fertilization


Onions benefit greatly from regular feeding through the fertilizers you may apply. A balanced fertilizer that is high in nitrogen can be applied in their growing seasons so that it stimulates healthy foliage and bulb development.

This should be done every few weeks so that your onions may grow large bulbs.

Note: You must stop fertilizing them once you see that the onions are pushing the soil away. This is the start of the growth of their bulbs. Also, refrain from pushing soil back around the onions. This stops the bulb from emerging from the soil.

6. Harvesting and Storage

You are ready to harvest onions when their tops start to dry and then fall over. When this happens, always remember to start curing them in well-ventilated areas until their tops are dry entirely.


By learning when to plant onions in Michigan, gardeners can now make informed decisions by carefully considering Michigan’s climate and frost dates. But the success of the garden is nothing without the will and effort of the person maintaining it.

Early Spring and Fall are one of the best-recommended dates for onion planting. But one should also consider spacing, watering, soil preparation, and harvesting management to nurture healthy onion plants.

Armed with this knowledge, you can embark on a rewarding onion-growing journey as you savor the flavors of their harvest!

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