How to Grow Onions in Pots
Choosing the correct varieties of onion to grow is necessary to get the best yield. Since onions are daylight sensitive and take several months to mature, there is some overlap as to which onions can be grown in specific areas.
When choosing onions, consider the number of days between freezes for your area, how many daylight hours you get during the summer, how long you would like to store onions, your preference for sweetness or pungency, and how you plan to use onions.
Growing onion from seeds will give you the widest selection of varieties, the biggest bulbs, and the earliest harvest. Onions grown from seed will also be more resistant to disease and store better than onions grown from sets. Onion transplants will yield similar results, but will not be available in as many varieties as from seed.
Most sweet onions mature about 4 weeks before more pungent onions, but sweet onions do not store as well as pungent onions. If you start onions from seed, you will get better quality onions, but onions from sets will produce more reliably. For more on growing onions, see How to Grow Salsa in Pots – Onions.
Heirloom Onions to Grow in Pots
Red Creole Heirloom Onions are red-purple, pungent, and spicy. Red Creole onions were developed in California in 1962. They are not a sweet as some red onions, but the spicy flavor is good for cooking. It is adapted to short day, southern, tropical and sub-tropical areas. These mid-sized onions are good for storing for up to 7 months and are ready to harvest in about 110 days.
Italian Torpedo Heirloom Onions are a favorite variety for Italian cooking. Its tender, mild, sweet bulbs are shaped like a torpedo with light red skin. Torpedo is best for long day areas and matures in about 110 to 120 days.
Cippolina Borretana Heirloom Onions are a good choice for creaming or boiling. These small white onions are also good raw. Thin to 2 inches apart and harvest in about 100 days.
Short Day Onions to Grow in Pots
Granex Yellow Onions are one of the varieties that can be used to grow Vidalia onions, if you happen to live in certain parts of Georgia, or Maui onions, if you live in Hawaii. Soil makeup affects how pungent an onion will be, and especially low levels of phosphorous are necessary to grow the sweetest onions. Granex produces will in warmer, short day areas, and is ready to harvest in about 160 days.
Contessa onion is a white hybrid and is a cultivar of Texas 1015 Super Sweet. Contessa onion plants get about 16 inches tall and should be thinned to an eventual distance of 7 inches. Contessa matures in about 100 days and stores for about 2 months.
Texas 1015Y, also known as Texas SuperSweet, was bred by Dr. Leonard Pike of Texas A&M and released in 1983. This world-famous, sweet yellow onion is open pollinated, and is one of the easiest onions to grow. It is named for its ideal planting date: October 15. It is ready to harvest in about 115 days and will store for 2 to 3 months. It can be grown as far north as Ohio, and is suitable for short day or intermediate day onion areas.
Giant Red Hamburger is a sweet, red and white onion. It grows to 10 to 12 inches, maturing in 78 to 80 days.
Intermediate Day Onions to Grow in Pots
Super Star Onions (aka Sierra Blanca) have won the AAS award. This white variety is well adapted to the central regions of the US and for northern short day areas. These onions will get up to 4 inches in diameter, and their tall foliage protects them from sunburning. Super Star onions will be ready to harvest in about 95 days and will store for about 2 months.
Candy Hybrid Onions are very sweet and mild. These flat yellow bulbs are adapted from northern Texas to the North. Candy onions get 3 to 4 inches across in about 80 to 90 days and should be spaced 4 inches apart.
Red Candy Onions are a sweet, mild red onion that are ideal for salads and salsa. These onions get about 3 inches in diameter in about 95 days and should be spaced 4 to 6 inches apart.
Red Marble Cipollini Onions are a miniature red Italian onion which stores well. Plant these intermediate day onions closely to gather to grow red pearl onions or further apart to produce 2 inch diameter onions. Red Marble Cipollini matures in about 90 to 110 days and should be thinned to 2 inches apart.
Rossa Di Milano Onions are a red heirloom onion from Italy. These long day to intermediate day onions do well in mild climates. These onions store well and grow to 4 to 5 inches in diameter. Rossa Di Milano matures and about 90 to 110 days and should be thinned to 4 inches apart.
Long Day Onions to Grow in Pots
Red Delicious Hybrid Onions are a sweet onion that can be started from seed and harvested within a 105 days. These large red and white onions are well-suited to northern gardens.
Red Zeppelin onions are a dark red variety which is good for storing for about 6 to 8 months. Red Zeppelin grows well in areas that do not have intense summer heat with at least 14 hours of daylight. These 4 inch globe shaped onions mature in about 110 days.
Walla Walla Sweet Onions are a sweet, mild onion for the North. It is similar in qualities to the Vidalia onion, and will store for 2 to 3 months. Plant Walla Walla onions 4 inches apart and harvest in about 80 to 90 days.
Copra Onions are a dark yellow onion variety that stores very well, for up to a year. Copra onions grow to 3 to 4 inches in diameter and have a bold flavor good for recipes. These long day onions mature in about 95 to 110 days and should be thinned to 8 inches apart.
With some planning and the correct storage conditions, you can have onions grown in your own garden year round.