Zone 8a Garden: Onions

If you are looking for how to grow onions, garden in Zone 8a and want a hands off vegetable, you’re in the right spot.

Spring is the time to grow onions in Zone 8a. Onions are an easy plant to grow, especially if you are looking for big harvests with little effort. They are one of the earliest plants into the ground. I water and feed them, then reap large harvests with great flavor.  Onions are heavily used, under appreciated and in our opinion, some of the easiest plants to grow in Zone 8a.

Last year, onions were the only crop that survived the monster that was the weather in spring. Flooding rains, two late snowstorms, sustained 20 mph winds followed by a scorching summer, and our onions we unphased. We grew yellow, white and red onions and pulled onions larger than baseballs from the ground 110 days later. We harvested our onions in late June, and shared or ate them all by September. All 100 of them. 

What is a growing zone?

Growing zones, or “planting zones”, refer to the areas in which America, and other parts of the world are divided into for planting purposes. These zones from 1a-13b, help categorize which types of plants are most likely to thrive in your climate, taking into account winter weather, summer heat and rainfall. Knowing this information gives you specificity when researching when to plant, how much to water, when to expect harvests and what will grow most naturally in your area.

You can determine which growing zone you are in by entering your zip code in the USDA Plant Hardiness Zone Website, or looking for your city on the U.S. growing zone map.

Do you grow onions from seed?

You can definitely start onions from seed, but it is a much longer process. Onions can take anywhere from 110 -250 days from seed to harvest – if you were planning to harvest onions before extreme summer heats in late June, you would have to start your onion seeds the second week of October the year before. 

What are onion starts?

Onion “starts” are another option – purchasing onion seedlings from a seller shortens the grow time to a short four months. Starts are typically purchased in the fall and distributed in the spring based on your zipcode and earlies planting date. The starts arrive with green tips, some dry layers and established roots. I’ll usually spread out on a towel until the right time for planting arrives, or your beds are ready. 

What type of onions are best for Zone 8a?

There are three different types of onions: long day, intermediate day, and short day onions. The types are determined by the amount of sunlight required for plant growth. In Zone 8a, our spring to summer days only reach around 12 hours of peak light, while northern regions may experience more than 14 hours of daylight. Our “shorter days” mean that short day onion varieties will grow best. 

Some varieties include:

Yellow – Texas Legend, Yellow Granex, Texas Super Sweet

White – Texas Early White, White Bermuda

Red – Red Criole, Southern Bell Red

When selecting your varieties, it is good to consider how you will use your onions and select a type based on their storage length. 

Where to buy onion seeds or starts?

You can purchase onion seeds on most seed websites such as Johnny’s Seed, Territorial Seed, Baker Creek Seed, Botanical Interests, or True Leaf Market.

We purchase our seed starts from Dixondale Farms, or find them in store at our local greenery. Dixondale sells onions in bunches that are either variety specific or a sampler of yellow, white and red in short, long or intermediate day.

What you’ll need:

1. Loose soil: whether planting in the ground or in raised beds, you will need to plant your onions in soil that has plenty of decomposed plant matter that is airy and crumbly. If you have clay soil, this may mean incorporating more compost or some sand into your top six inches of soil. For raised beds, you can find a “rose” or “tree and shrub mix” that will keep your beds soft after repeated waterings. Topping rows or beds with finished compost is always a great way to provide your young plants the nutrients they will need during initial growth.
2. A planned bed: Onions need to be planted in at least 10 inches of soil, and rows or beds need to account for onion spacing. We plant them 4 inches from the edge of your planting area and 2-4 inches from each other. (Onion seeds should not be directly sown, but started indoors in trays.)
3. Onion starts
4. Fertilizer: Onions require fertilization at the time of planting with ammonium sulfate or calcium nitrate, as well as every 2-3 weeks during the growth season. Find exact directions on how much and how often in Dixondale’s onion planting guide.
5. Watering system: Onions will need ample watering during their growth or bulbing season. Drip irrigation around the heads of each start, or overhead watering work well. You can check the moisture level of your soil by pushing a finger down into the ground up to the second knuckle. If you feel moisture, retest the next day. If not, its time to water. I used a rotating sprinkler on a timer, but watering amounts can be tricky. We tested the gallon per hour by placing a bowl in the garden and setting the timer for one hour. We determine how long we should water weekly with this method, and how much water loss is due to wind. Onions will do better with infrequent heavy watering than with daily light watering. 

What do I consider when planting onions?

Once you have determined your bed size for the amount of onions you would like to plant, and your soil is prepped, the last consideration for onions is weather. Your growing zone will help with providing ideal planting dates, and your onion start company will distribute onions at the appropriate time. However, we have still run into weather conditions that require a judgment call on when to plant. If there is a freeze (temperatures below 30 degrees for multiple evenings) during your ideal planting dates, it is better to delay planting to a warmer window. Onion starts have shallow roots, but once established, are incredibly cold hardy. In the case of a freeze, continue to have your starts laid out in a dry and warm area 

Planting instructions: 

1. Plant your first start 2inches from the edge of your row or raised bed. Each start should be 1 inch down.
2. Plant each sequential onion 2-4 inches from the first in a row. 
3. Between each row, leave a total of 16 inches. Starting from your row, measure 6 inches, and dig a 4 inch wide trench the length of your row.  This will act as your fertilizer trench. 
4. Add a ½ cup of fertilizer for every 10 feet of row at the time of planting. From your fertilizer trench to the next row, there should be another 6 inches.
5. After 2-3 weeks, fertilize onions again on top of the fertilizer trench and water in. I repeat this until the onions begin to bulb. 

Bring on Spring; Grow Onions!

Onions are one of the first things to kickstart the garden during the cold of winter. We are days away from planting our own and can hardly wait to get our fingers back in the dirt. This year, we’re more than tripling our planting with the goal. We aim to have one onion a day for a year, and some to share. We haven’t had to till up a large plot of land to prepare for such a large amount of onions. Instead, we’re planting in square raised beds, making onions one of the easiest crops to grow in bulk here. While it is gray and windy, it is hard to imagine sitting poolside with a grilled burger and fried onion rings from the garden. But it is that greasy hope that brings us through winter into spring!

To learn more about what we’re growing, read more about us here. Have you grown onions in the south? Share your best tips and tricks in the comments below!