Many of us would love to have fresh onions in our lives, but with a small garden or no garden, we don’t see how to do it. The solution is to grow onions in containers. You can use onion growing pots to create a small space – indoors or out – to grow your own delicious onions.
How To Grow Onions (Generally)
You grow onions in a pot just like you do on the ground. You want good soils, good drainage, good fertilizer or soil composition, and plenty of light. Like garlic and chives, onions are part of the Allium family.
When you’re growing onions, you’ll note that the more leaves you have, the more layers on that onion. If you have a lot of leaves, you will have big onions. (Just as a side note, my favorite is the variety Candy, which comes in at about a pound an onion and has the most onion-y smell in the world.)
You can grow from seed, but it takes a lot of time, and for those further north, onion sets might be better. You can plant these marble-sized onions when the temps hit about 50 degrees Fahrenheit (10 degrees Celsius). Make sure you put them somewhere that will get a lot of sun.
If you want to grow in a pot instead of a garden, the biggest issue is choosing your pot.
General rules for growing onions in pots and containers
Before we list out types of pots and containers that work for growing onions, here are a few tips for choosing onion-growing pots and containers:
- Traditional terra cotta flower pots work if you’re not growing too many onions. Large round galvanized tubs work, as do large plastic tubs, so long as both of them are at least 8 inches deep. Half-whiskey barrels (or any other half-barrel you have) also work well. You can even look at the bins that flats of seedlings come in. If not deep enough for bulbing onions, they may work for scallions or chives.
- Some people prefer several small containers to one large one. This allows you to place your pots more flexibly and makes them rather easier to move around. A 3-5 gallon pot or a container at least 8 inches in diameter and 12 inches deep will get you off to a great start.
- You can grow about a half dozen onions or garlic plants in that size. Ceramic and terra cotta work well, but the soil dries out faster, so keep an eye on the moisture.
- You can, of course, use classic flower pots for growing onions, but at the sizes you’ll need for bulbing onions, they’ll be rather expensive. Deed window boxes work well, as do tubs and other wide containers. Make sure to put your pot on a stand to keep it somewhat off the ground.
How many onions can you grow in a particular size of pot?
The following are general onion-spacing guidelines:
Sow the seeds a quarter of an inch deep and a half-inch apart. When the young plants are several inches tall, thin them to 1 inch apart for green onions, 2 inches apart for small to medium-sized bulbs, or 4 to 6 inches apart for large bulb onions [Savvygardening.com].
Example: 10-inch diameter circular pot can accommodate 8 onion bulbs. This is calculated by getting the square inch total of the pot (radius squared times pi) divided by 9 (3″ x 3″ space needed for each onion). It comes to 5″ radius x 5 x 3.14 = 78.5 inches squared divided by 9.
Shape of container will make a difference.
1. Large pots (8″ to 10″) are best
To start with, you’re going to need a biggish pot. Something at least ten inches deep but at least a yard wide would allow you to plant enough onions to produce a real crop. If you’re thinking about bigger onions instead of, say, scallions, you’ll need a pot big enough (or enough pots) to allow for about three inches around each onion. Make sure your pot, whatever it is, will support plants that may get to three feet tall.
Many people use plastic tubs, much cheaper than pots of the size recommended, to grow onions. Plus, it is relatively easy to put drainage holes in your plastic tubs. The example above is a simple plastic pot.
b. Ceramic planter (10″)
Another option is something more decorative such as a 10″ ceramic planter pot. Here’s a great example:
c. Terracotta Pots (10″)
Similar to ceramic are decorative terracotta plant pots. Here’s an example:
2. 5-Gallon Nursery Pots
Another option is the five-gallon bucket. It’s plenty deep and easy to create drainage. But the relatively narrow top means you will not get many plants in it. An onion needs three inches of open soil around it to grow well.
You can grow a small crop in a four-gallon container. Fill halfway with wood chips for drainage and then finish with posting soil. Keep the soil moist, and your sets will grow. Remember, though, if you’re growing bulbed onions, you’ll only get a few in this pot.
3. Growing Bags
For something less expensive and easily stored, you can go with fabric pots. For onions, you’ll want a larger size such as 5-gallon bags. Here’s an example (these are becoming a popular option for onion growers and other vegetable growers).
There are different designs of fabric grow bags. Here’s an example with side flaps for accessing your harvest (which aren’t necessary for onions but if you have them for other crops, they’ll definitely work just fine):
4. Planter Box (trough-design)
If you go with planters, with which you can grow many onions in one pot, be sure it’s also fairly deep. Here’s an example of a stylish metal 8″ deep planter:
Source for above metal planter box: Etsy
5. Onion Grow Kits and Systems
With vegetable growing becoming so popular, you can buy grow kits and systems for all kinds of onions. Here are some popular examples:
a. Green onion grow tray
Source for above onion grow tray: Etsy
b. AeroGarden Grow System
These grow systems offers “hands-free” vegetable and herbs growing indoors. They’re probably more economical for growing herbs but you can grow onions if you wish.
You can buy the above grow system here.
Fun onion growing containers and options (kids love this stuff)
As a project for your kids, place a sprouted onion with the root down in a glass of water for a change. It will continue to shoot, and you can either use the new top part in cooking or plan the whole thing in the soil. It’s similar to sprouting an avocado pit.
Another project that the kids will enjoy is growing onions vertically in a bottle. Get a five-liter bottle(think about the big bottles that go on a water cooler) and put it with holes in it. Put sprouting onions in different soil layers with a hole for each onion. Keep them well watered and watch them spout out the holes, seeking the sun. You can find detailed instructions for creating your vertical onion garden online.
Advantages to Growing Onions in Pots
You control everything: how much light, how much water, what’s in the soil. You can move them into a shadier location if they grow too fast. If you’re a control freak like me, growing indoors is excellent.
Harvesting is fantastically easy. As we get older, bending over to harvest things in a garden becomes increasingly challenging. With containers and pots, you can put them wherever you like, which means at a height that is convenient for you. Then, you’re just pulling the onion out of your easy-to-reach pot.
Growing indoors means you don’t need land or a yard. You can use your apartment or its porch or balcony to have all the onion growing room you need.
Nothing is Perfect
There are, alas, also disadvantages to growing your onions in pots. First, depending on the size of your pots, you may get fairly small onions simply because they don’t have enough room to get big. Second, you need to be sure to hit it right with water.
Too little and they’ll overheat and mold; too much, and they will get diseased and moldy. Aim for the perfect middle ground. Another container water issue is that your pots can dry out very quickly in the summer. Check them daily to keep the plants adequately moist.
Where to Put Your Pots that Are Growing Onions?
As we said, your onions like a lot of sun. You need to put the pots somewhere to get six to seven hours of sun every day. You can add to your light with grow lights if you’re growing inside. Shoplights work well. Many gardening shops now carry grow lights. Just make sure your potted onions are getting good light from some source.
What Kind of Onions Can You Grow in Pots?
Various onions will work well in pots. When looking at onions, you’ll see them referred to as short-day or long-day. This terminology refers to how many hours of sunlight the onions need to produce well. Growing in containers, of course, you can control the light easily. Nonetheless, even growing inside, life is simpler if you pick an onion suited to your growing zone. The following considers some of them.
These are known as spring onions or scallions, or green ions. They’re tender and delicious when fresh and can be picked at about two months. Some suitable varieties include:
- Crystal White Wax – good for pickling. Mature in about 95 days
- Evergreen Long White – certified organic, long slender stalks with small white bulbs. Produce exceptionally well.
- Toyko Long White – One of the very best green onions. Good long white bulbs and sturdy green tops. Good disease resistance.
These take longer to grow than green onions but have a gentler taste than stored onions.
- Alisa Craig – Large heirloom onion, mild and sweet. It takes about 100 days to harvest.
- Italian Torpedo – a narrow purple/red onion, good for Italian cooking with a mild sweet flavor. About 110 days to maturity.
- Red Burgundy – Globe type, best enjoyed fresh. It’s an heirloom that’s mild and sweet, with good disease resistance.
- Utah Yellow Sweet Spanish – Sweet small variety, producing onions in about 115 days, sweet and mild.
- Walla Walla – Large onions, very sweet, and very mild. They are fully mature in 90 days with heavy water content.
- White Grano – Large white bulbs, best used fresh and raw.
- Golden Creole
- Sweet Spanish White
- Maui Onions (Texas Grano) – The Maui Onion, incredibly sweet, is actually the Texas Grano. Its producers claim the soil and environment of Hawaii produce the special taste, but if you want to give them a try, order the Texas Grano.
These are for keeping rather than serving when picked.
- Candy – This author’s absolute favorite onion in the world. Last fall, I bought 50 pounds of locally grown Candy and finished them in late March. They are still in excellent condition and are the best tasting and smelling onions I’ve ever had. This is my go-to for growing. Mild bite, crisp, and delicious.
- Patterson – a reputation for being very long-storing, easy to grow, and producing medium-sized bulbs. A bit of a bite and suitable for cooking.
- Southport Red Globe – Heirloom with large bulbs with purple skin and pink flesh. Producing in about 10-120 days.
Watering Your Onion Plants
Like all plants, onions need water. And in a container, you have to be even more careful because you are the only water source your plans have. You need to make sure they’re getting at least two to three inches of water a week. Check your potted onions daily; if the soil is dry, water them. Mulching the plants will help keep the soil moist. Use fine mulch that won’t crowd your bulbs and keep them from the light.
Feeding Your Onion Plants
If you start with onion sets or seedlings, they will grow faster. Use a seed-starting potting mix for these to give them the best start.
- Gardeningknowhow.com/grow onion in container
- Gardeningknowhow.com/grow onion in the garden