How to Start Onions from Seed I

Onion Seedlings

For many people, the easiest way to start your onion growing career is to start from sets. These sets are small, immature onion bulbs you can plant easily. They are ideal for beginners because they are very easy to care for so anyone can have onions in their garden without much trouble.

If you’re only starting out as an onion grower, these sets are the best choice for you. It may turn out that you will never want to move to something else. Nothing wrong about it: starting onions from sets is easy, practical and gives you plenty of fresh onion for all your culinary needs.

However, there’s one big problem with onion sets: they usually come only in a few types and varieties. If you want to start your onions from set, you are faced with a very limited choice. To choose between more varies types of onions and to be able to grow a variety of your choice, you will have to start your onions from seeds.

Growing Onions from Seed: The Advantages

Growing onions from seed may be more challenging and complex, but it also gives you so much freedom and varieties of choice. If you choose to grow onions from seed, you will be able to pick onions of a specific shape, color and size you are interested in. Not only that, but you you will also be able to pick a variety based on other features (early-season, late-season, etc.) When it comes to diversity, starting your onions from seed is the best choice.

Another advantage to onions started from seed is plant health. Onions started from seed tend to be less prone to disease, so it’s another thing to keep in mind. Also, these onions are known to bulb up faster and they also store better.

Indeed, there are many different varieties with many different features to choose from. When it comes to color, you may choose between pure white onions, various shades of yellow, to dashing purple onions. You may also choose various sizes and shapes, such as plump Ailsa Craig Exhibition or the bottle-shaped Italian Torpedo.

Onion Seedlings

Different Varieties

One of the most important choices you will need to make is the variety you want to start from seed. There are so many varieties available that you will need to take some time to choose the best one for your needs. It’s fun to go through a seed catalog to pick the best ones for your family.

Also, keep in mind that onions need a long growing season so it’s best to place your seed orders early so you can get a head start on the growing season.

When choosing the best variety to grow, don’t forget your climate conditions and your zone. Remember, onion varieties require different length of daylight and the temperature to make a bulb. There are the so-called “short-day” types that don’t require much sunlight, so they are ideal for places with cold fall and winter months. They will bulb when they receive 12 hours of sunlight, which happens with the warmer, summer weather. The “long-day” types are great for places with longer summer daylight. These onions require at least 14 hours of light to bulb up. They will grow foliage in the spring and bulb up in the summer.

In case the short-day varieties are grown in a warmer weather, they will bulb up too early, but then they will languish so they will never get to the optimal size. Now, it may be exactly what you want (for example, if you want pickling or pearl onions), so it’s not a mistake per se. In case you grow long-day onions in places with colder weather, they will produce lots of leaves, but almost no bulbs.

When choosing the onion variety you want to grow, in addition to climate conditions you also need to know how you want to use onions in your kitchen. Each variety is ideal for some culinary uses but not the others.

Here are some of the most popular onion varieties you can grow:

  • Copra. This is an early onion and it has blocky globe bulbs of a medium size. Their skin is dark yellow and the bulbs are rock hard. Ideal for storing. This variety has the highest sugar content of the all storage onions. (104 days to maturity).
  • Sweet Sandwich. This is a globe-shaped and very sweet onion. It can easily be stored and it’s ideal for cooking and sandwiches (105 days to maturity).
  • Red Baron. This is a big, purple-red onion. Great for storage. (108 days to maturity).
  • First Edition. This is a medium-sized onion with pungent flavor. Good for storage (105 days to maturity).
  • Ailsa Craig Exhibition. This is a round, huge, snow-onion with a straw-yellow skin. The taste is mild. This onion type should be stores in the late fall (110 days to maturity).
  • Lancastrian. The so-called “football onion”. It averages in size of about 5lb. It’s crisp, sweet and ideal for stuffing and onion rings. Can be stored only for a short while (95 days to maturity).

Starting Onions from Seed

Most of the time, you will need to start your seeds inside the house. It depends on your climate, of course, but typically, the climate will be too cold in January and February to be able to start your seeds outdoors. On the other hand, waiting until mid-May to start seeds outdoors is too late.

This is why it’s best to start the seeds inside, about two months before the last frost. For most people, it’s best to start seeds in January or February. It’s important to do it like this, or you will end up without quality bulbs to harvest.

To start the seeds, sow them about 1/4 inches in flats previously filled with soilless potting mix. It’s best to cover the flats with a plastic top. This will preserve the moisture your onion seeds will need to grow. Place the flats on the heated floor or the sunroom.

It’s important to know that onion seeds germinate in about a week, provided they are on a temperature of about 70 degrees F. You will soon see stringlike tops poking though the soil. This is when you should change the growing conditions. Remove the plastic top and relocate the flats to a cool place (such as an attic or a garage). You will need to place them under fluorescent light: one warm white and one cool white bulb per fixture. It’s best to keep these lights just above the leaves. As the plants grow, you should adjust the lights.

Another thing to do is to feed your seedlings with a water-soluble fertilizer at half strength every other time you water. Keep in mind not to keep the seedlings too wet. Observe your onion seedlings and watch them grow.

When the seedling leaves are about 5 or 6 inches tall, it’s time to transplant them. It usually happens in mid-March. Keep in mind that you have to be very careful, because onion seedlings are very fragile. It’s a tedious job so some people choose to skip it and go directly from flats to the garden. However, transplanting your seedlings into six packs first offers advantages. It gives each plant its own growing space, so they have a better chance to grow strong roots.

When transplanting, overturn the flat carefully to expose the seedlings’ roots. It’s best to handle the plants by the leaves. Gently tug to separate the roots of individual plants. After this, tuck each of the plants into the new cell without damaging the roots.

After the seedlings are on their new place, snip the leaves back to about 4 inches with scissors. This will prevent the plant from becoming too top-heavy. This is also a way to ensure that more nutrients will go to the roots instead of the leaves.

Continue watering with half-strength soluble fertilizer and keep the transplants under the lights. In case the weather allows, you may also move the transplants to a cold frame. Keep in mind that onions are cold-hardy plants so they can tolerate cold temperatures. However, you should usually wait till mid-April to move them to a cold frame. It’s best to locate the cold frame in the south side, so they can receive the full sun. It’s essential for growing strong onion plants.

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