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Easy-to-grow onions create perfect flavor for butternut squash soup

By Liz Cardinal
Special to the American-Statesman
Red and yellow onion sets are easy to put into the ground and grow.

Considering how easy they are to grow, and that they are edible in all stages of their growth, bulb onions are definitely worth adding to your January garden. The only downside to growing your own bulb onions is that you will wish you had more space to grow enough for your cooking needs.

Bulb onions can be grown from seeds that are started in early fall, but they are very easy to grow from sets in January. Sets are bare-root, young plants. They come in bundles and can be ordered online or found at local nurseries. Make sure your sets come from Southern U.S. growers, as they will most likely be short-day onions, which are suitable to grow in Texas in winter when we have the correct temperature but limited daylight. 

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To grow big, healthy bulbs, three things are essential: well-fertilized and loose soil, full sun for six to eight hours, and regular watering. Good varieties to grow in Central Texas are Yellow Granex, Red Creole, 1015 Y and White Bermuda.

Before planting, loosen the soil and fertilize with an all-purpose, granular fertilizer with a high middle number like 10-20-10. The middle number represents the phosphorus, which is essential for plants to make strong roots and bulbs. Dig a trench 4 inches deep and 4 inches wide. Sprinkle ½ cup fertilizer per 10 linear feet of row.

Onions planted 4 inches apart are easy to grow.

Cover the fertilizer with 2 inches of soil. Now, with a pencil or chopstick, make small holes about 4” apart down the row. Place one onion start in each hole about 1 inch deep then backfill with the soil until it is level. Be careful not to plant them any deeper as this will inhibit bulb growth.

Fertilize again with a liquid fish emulsion or more 10-20-10 fertilizer between rows when four to five leaves emerge, then stop fertilizing when the bulb appears.

Pests are generally not a problem, and onions can survive temperatures in the 20s; they are pretty much maintenance-free. All you need to do is continue to water regularly. If the leaf tips begin to yellow, that is a sign of overwatering. 

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You can harvest onions at any point and use them as green onions, or about 90 days to 110 days after planting, the leaves will begin to turn yellow and eventually flop over. That is when you know they are ready to harvest.

Stop watering at this time and let the soil completely dry out. You can use the onions right away or let them cure so that they can be stored for later use.

Short-day onions do not store as long as long-day varieties, but if cured properly, they can keep at room temperature for a couple of months. To cure them, after harvesting, don’t wash them or cut their leaves off, just brush the dirt off with your hands and lay them in rows of single layers in the sun for 2 days. Next, move them to a shady, well-ventilated spot for another 2-3 days. A picnic table under a tree works well. The outside skin will begin to dry and the entire neck of the onion will be dry. At this point, you can clean and trim the roots, and cut off the leaves with scissors about 1 inch above the bulb.

Newly planted onion sets will grow until their leaves start to yellow. Then you should stop watering, let them dry and pluck them from the ground.

Bring the bulbs inside and store them in a cool, well-ventilated area in a mesh bag to allow airflow. How long your onions will keep depends on how well they were cured. Periodically, check the onions and use soft ones first so they don’t spoil the others. 

Dixondale Farms is the most recognizable onion grower in Texas, and you can find more info on growing onions as well as mail order onion sets from them directly. The Natural Gardener, Garden Seventeen and other garden centers will have onion sets in stock in January. 

Onions are used almost daily at my house. They add depth and aromatics to cooked dishes. The recipe below features butternut squash, which you can find all winter at farmers markets. This soup amplifies the caramelized, buttery flavor by roasting the onion and squash before adding them to the soup pot. And roasting the squash with its skin on makes scooping out the pulp easier than peeling it raw. 

Roasted Butternut Squash Soup  

2 (2 pounds each) butternut squash 

2 tablespoons olive oil

2 cups coarsely chopped yellow onion

5 cups chicken or vegetable broth

1 teaspoon curry powder (optional)

2 tablespoons molasses 

¼ teaspoon ground red pepper 

1 teaspoon salt

½ cup full fat coconut milk

Chopped fresh thyme for garnish 

Preheat oven to 425 degrees.

Cut each squash in half lengthwise; discard seeds and membranes. Place squash cut-side down on a baking sheet coated with 1 tablespoon olive oil. 

Bake at 425 for 30 mins. 

Combine onion with remaining 1 tablespoon olive oil. Place on baking sheet with squash and finish baking together for about 15 minutes or until the squash and onion are tender. Cool slightly. Scoop out squash pulp from skins; discard skins. 

Place onion and squash pulp and the next 5 ingredients (through pepper) in a Dutch oven; bring to a boil. Reduce heat and simmer for 10 mins. 

Remove from heat and use an immersion blender to blend until smooth. 

Add coconut milk and stir until combined. 

Ladle into bowls and garnish with thyme.