Types of Multiplying Onions
Unlike yellow and red onions, which reproduce through seeds, multiplying onions reproduce through the making of bulbs. This is known as vegetative propagation. The following multiplying onion varieties are the most common for fall planting.
Bulbing Multiplying Onions
When you plant bulbing onions in the fall, they reach maturity in the summer. One bulb can produce around 14 bulbs in a cluster. The size of the bulbs depends on the variety. When you harvest your multiplying bulbs, keep a few for replanting. Bulbing multiplier onions are also know by the following names:
- Potato onions
- Hill onions
- Ground onions
- Inground onions
Top-set Multiplying Onions
These perennial multipliers form bulblets at the top of tall onion stalks, rather than forming onion bulbs underground. The purple bulbs are small, usually around one-half to 1 inch in diameter. If the bulbs become too heavy, they fall over onto the soil and replant themselves. One variety, the Catawissa is an Egyptian onion that can send out tendrils that root in the ground.
Common uses for these bulbs are in soups, salad dressing and pickling. They keep in storage for several months. Top-set onions are also known as:
- Egyptian onions
- Tree onions
- Walking onions
Shallots
Although most people don’t think of shallots as onions, they are multipliers that don’t produce seeds. The flavor of shallots is more subtle than onions, and tastes like a cross between an onion and garlic. You plant them in the soil in the autumn just like other multiplying onions. Each shallot bulb grows up to a dozen small bulbs.
Planting Multiplying Onions
Plant your multiplying onions underground in rich soil, supplemented with hardwood ash and bone meal. You can also spread organic mulch around the base of the plants for added nutrients. The best months to plant multiplying onions in the U.S. are from October to December, as long as the soil isn’t frozen.
Set your onions 2 to 4-inches deep. Space them from 4 to 6-inches apart. If you’re planting more than one row, separate the rows by 8 inches.
