How do you grow onions from an onion?

QUESTION: What can you do with bottoms of onions? Can I use them to grow more onions and not throw them away? How do you grow onions from an onion? -Jim T

ANSWER: By chopping the bottom of an onion bulb off and planting it into soil, you can grow your own onions from cuttings. With a bit of knowledge, as well as time, patience, and lots of water, you can grow an onion from an onion bottom in just 90 to 120 days. You can use most any variety of onion for this technique, even onions purchased from the grocery store. Make sure that the onion that you are using is still healthy and fresh.

First, chop the bottom of the parent onion about one inch from the bottom using a sharp knife and remove the outer peel. If you are growing your onion indoors, you can plant it at any time of year, but if you are growing it outside, you should start your cuttings in early spring.

Next, leave the cut onion bottom out to dry for 12 to 24 hours on a dry surface with the cut side facing up. Let the onion bottom dry out until it is dry to the touch and calloused. Make an X by poking four toothpicks into the sides of the onion bottom, pushing the toothpicks halfway in on each side. The toothpicks should be equally spaced apart, allowing you to suspend your onion bottom over water while it develops roots.

Then, fill a small bowl to the brim with water and place it on a flat surface, preferably a sunny windowsill, hanging your onion bottom on top so that the bottom touches the surface of the water and leave it in place for three to four days. The bowl’s diameter should be less wide than the length of the toothpicks. Once the cutting has developed white roots from the bottom side, it is ready to plant.

Next, fill a large pot with drainage holes in the bottom about halfway full with a well-draining potting mix. Place the onion cutting in the pot, positioning it in the center, root-side down and fill the rest of the pot with soil, leaving one to two inches of room at the top of the pot. You can keep the pot indoors or outdoors in sunny weather, just make sure it gets as much sunlight as possible. You can also choose to grow your cutting outdoors in a garden bed, as long as your garden soil is well-draining and you select a sunny location. Water the onion cutting immediately after planting it, giving the cutting enough water so that the soil is moist but not soaking wet.

After watering, spray a nitrogen fertilizer into the soil, following the directions on the label for how much spray to use. Give your onion about one inch of water per week, watering when the soil is dry to the touch on the top layer. Pull up any weeds regularly if you choose to plant your onion outside. Fertilize your onion every two weeks with a nitrogen-rich fertilizer until the bulb begins to poke from the soil. In approximately 90 to 120 days, the onion will begin to form flowers. This means that your onion is ready to harvest. Pull the onion out of the ground by pulling on the base of its green foliage to dislodge it from the soil.