Despite being easy to grow, onions were the bane of my homesteading existence for a good few years. Growing in the height of the fiery Portuguese summer proved to be too big of a challenge.

Health wise, onions are anti-inflammatory and high in both antioxidants and sulfur-containing compounds–some of which have beneficial effects. This root vegetable has been linked to improved bone health, lower blood sugar levels, and a reduced risk of cancer.

Onions are best eaten raw, and will begin losing their sulfur compounds and quercetin when cooked –. two of their most beneficial elements. Raw onions also contain dietary fiber, which is crucial for proper digestion and elimination of waste from the body.

It’s not hard to incorporate raw onions into your meals. In burgers, salads, or in more traditional mains, if you can stomach the extra peppery kick then I would consider raw onion –or nearly-raw onions (less than 2 minutes of cooking)– a far simpler and flavorful way to consume them, and they add more texture to your dishes, too.

The onion that we grow is the well-known heirloom variety �Stuttgart� which originates from the Netherlands. The bulbs are large and round and weigh around 70 grams (2.5 ounces), and offer a sweet and mild flavor.

Sowing Onions

To avoid the fierce summer heat we sow our first crop of onions in early January, in trays of homemade compost placed in a heated poly tunnel, and then our second crop is sown in late-August.

With a soil temperature above 40F (4.4C), onion seeds will take around 10 days to germinate, but a bit of warmth will speed things up — a soil temperature of 70F (21C) could see them sprout with just a few days.

We ‘multi-sow’ our onions; that is, we will drop approximately 4 seeds in each compartment of a seed tray and allow all to grow on until it’s time to transplant.

Transplanting Onions

Transplanting is done when the young plants are at least 4 inches (10 cm) tall. This ensures that a strong root system has had time to develop.

To acclimatize the plants, we’ll move the trays out of the poly tunnel for a few hours a day in the lead-up to transplanting. This gradual exposure to elements such as wind and rain also works to strengthen the stems.

While onions are a cool-weather crop, young plants will not fair well during a frost and so transplanting only occurs once the threat of frost has passed.

With regards to spacing, we plant each ‘clump’ (of 4-or-so plants) at a distance of 10 inches (25 cm) apart, in rows 15 inches (38 cm) apart, which see us grow many more onions per sq ft than traditional techniques allow.

We are careful not to plant too deep as this can lead to a number of issues, including thick stems (making the onions poor for storing). A generous watering follows transplanting.

A layer of organic mulch is an advisable addition to the bed. Mulch locks in warmth, retains moisture and suppresses weeds. Depending on the material, mulch can also deter pests, too, such as slugs and snails.

Growing Onions

Well-rounded onions are consistently achieved so long as we grow in loose, well-draining and fertile soil. This is especially important when multi-sowing — the plants need all the nutrients and space they can get.

Multi sown onions. As the bulbs grown they push one another away to make space.

Watering evenly is also important, which is where I failed during our 40+C (104+) summers.

Watering thoroughly after planting is key, and I managed that, it was thereafter where I messed up. Onions have shallow roots, and despite regular watering my soil at the base of the plants would routinely dry out and crack.

My mistakes: 1) back then I considered water a premium, conscious that our aquifer would dry out so likely held back at times when I shouldn’t have (it never has run dry, not even nearly), and 2) my mulch was severely lacking, more a cursory sprinkling of leaves rather than the thick organic layer of moisture-retaining, temperature-regulating material that it needed to be.

Be mindful of the flip side though — over-watering can be equally problematic. If leaves develop a yellow tinge, you should likely cut back.

Harvesting Onions

Our Stuttgart onions are ready to begin harvesting around 130 days.

The bulbs have started to fatten up around this time, which is also an indication to cut back on the watering.

We begin harvesting individual onions as and when needed, making sure to pick the smallest onions out of each ‘clump’ first/early (very early if we want spring onions), which allows the others the extra time and space grow on, bigger.

Another sign of harvest will be the plant’s leaves, these drooping/bending to the ground and discoloring tells you that your onions are done growing. We will allow the bulbs extra ‘fattening-up’ time after the leaves have died back.

Gently lift onions from the soil by hand–no soil disturbing tools required.

Any damaged onions should be eaten first as these will not store.

Overwintering Onions

As the space allows, we will simply leave onions in the ground over the winter to harvest as-and-when needed. The cold of winter will kill off the onions tops, but the roots will store very well underground.

This option is possible where winter temperatures don�t dip too low (below 10F/-12C). But even for areas where the occasional deep freeze does hit, overwintered onions should work just fine under a layer of mulch.

Note: be sure to pull-up all of the onions before the following spring (unless of course seed-saving is your intent). Onions are biennial and will send up stalks when the warmth returns, and flower, ruining the bulbs.

Curing And Storing Onions

If garden space is at a premium, or if you merely like easy-access and/or the site of braided onions hanging about the place, then picking the onions soon after harvest makes sense.

Curing the harvested onions is a key process, which sees the outer layers dry out and tighten to form a protective wrapping around the bulb.

For us, curing means laying the onions out in a shaded, dry, and cool place –usually in one of our sheds– out of direct sunlight. This was another mistake I made early on. I figured the baking sun would crisp up the onions good and proper. It crisped up the skins alright, but it also cooked the insides, turning them into a gooey mush.

Once cured, the onions can be ‘braided’ or ‘strung’. This, for me, is the best storage method as the strings can then be hung around the house which saves on pantry/root cellar space.

Alternatively, storing the onions in a wooden crate, or the like, allowing for good air circulation, and placing in a cool spot will work well too.

If properly cured and cared-for, onions can store for over a year.

A Word On Heirlooms

Heirlooms are old-time varieties that produce offspring with the exact same traits planting after planting, season after season, generation after generation — some heirloom seeds date back hundreds of years, or more.

Saving seeds from a hybrid variety, such as you would buy from most garden centers, would mean that the second generation you grow isn�t guaranteed to produce the same �true to type� plant, and in turn fruit.

If seed saving is your aim –which it should be in my opinion, in order to preserve healthier, naturally pest-resistant and true to type varieties– then having your own heirloom (sometimes called “heritage”) seed vault is essential.

For more on seed-saving from heirloom onions specifically, click the link below: