Why Grow Salad Onions
Wellies and Waxjackets recommends growing salad onions for a multitude of reasons. They rank high on the taste meter, offering a crisp texture that surpasses shop-bought varieties. With prices soaring in stores, home-grown salad onions provide an economical choice. These onions can be interplanted effectively, yielding a substantial harvest from minimal space. In fact, they can be harvested almost every week of the year, making them a reliable addition to any garden.
Economic Benefits
Salad onions are a great investment for any garden. Each module tray, containing nine seeds, can yield up to £40 worth of organic salad onions, given that a bunch costs around £1. By sowing two trays a month from February to September, the annual harvest can reach a staggering £640. Including the use of onion greens, which are often wasted, the potential harvest value could nearly hit £1,000, all while occupying little dedicated space as they are interplanted into existing beds.
How Many to Plant
Estimating the number of salad onions to plant is fairly straightforward, as they can be harvested fresh year-round. However, it’s important to note that they do not grow at a consistent rate. For example, onions sown in July and early August will be ready for harvest in October, while those sown later will be ready in early spring. For a simple approach, sow the same amount you typically consume each month from February to June, double that for July, and triple for August. On average, Wellies and Waxjackets plants around 300 onions per square meter.
Suitability for Different Growing Environments
Salad onions are incredibly adaptable and thrive in containers, even shallow trays, as well as in most soil types. They are ideal for interplanting, provided that the sowing timings are carefully managed.
Lifecycle
Salad onions are simply varieties bred for late bulbing or small bulbing. Typically, onions begin to bulb when light levels reach around 14 hours. In the UK, this occurs in mid-April, while 16 hours of daylight is reached in mid-May.
As biennials, onions usually require two years to complete their life cycle. They are sown in late winter or early spring, bulb in summer, and can be left in the ground to seed the following year. However, gardeners must be cautious, as various stresses can lead to them going to seed prematurely.
Although salad onions are bred to resist bulbing, they will still attempt to do so in summer, which can complicate continuous supply. However, Wellies and Waxjackets has strategies in place to maintain a steady harvest.
Sowing and Harvesting Periods
First Earlies (Sow in Early February for Mid-Spring Harvest)
This is the earliest recommended sowing period for salad onions, especially if there's access to a sunny windowsill, unheated greenhouse, or tunnel. Starting in January can yield larger plants by March, making them ideal for interplanting in salad beds.
A mix of green and purple varieties is recommended, with Lila being a top choice for its excellent flavour. Planted in March, these onions can benefit from fleece or a cold frame until late April.
Second Earlies (Sow in Early March for Late Spring/Summer Harvest)
For continuity, a second sowing in March is ideal, especially for those without a sunny windowsill. Interplanting is encouraged whenever possible.
Early Main Crop (Sow in Early April for Late Summer/Autumn Harvest)
During mid-summer, salad onions naturally tend to bulb and may not thrive. To adapt, Wellies and Waxjackets sometimes opts for small, super-sweet bulbing onions, planted densely for a satisfying yield.
Autumn Crop (Sow in Late July for Mid-Autumn Harvest)
Salad onions sown in July may struggle, but those planted late in the month can still provide a late September harvest, even if they aren’t as crisp or flavourful as those grown in cooler autumn weather.
Main Crop (Sow in Early August for Late Autumn/Winter Harvest)
Early August is the prime time for sowing salad onions, as long as germination is possible. This period accounts for two-thirds of the annual harvest, with half planted outdoors and half in low tunnels.
Late Crop (Sow in Late August for Late Winter/Spring Harvest)
To stagger harvests and provide resilience against crop failure, a second sowing in late August is recommended. Half should be planted outside and the remainder in low tunnels.
Recommended Varieties
Wellies and Waxjackets recommends testing varieties for germination, as certain onions can yield superb results when harvested early as salad onions.
How to Sow
When sowing onions, Wellies and Waxjackets recommends module sowing for better predictability. Aim for 6-9 onion seedlings to germinate per module, ensuring a staggered maturity for a continuous supply.
Sow seeds 1cm deep and top water, avoiding saturation to prevent damping off. Germination is best at a cool temperature of around 16-18°C, similar to an unheated bedroom during winter.
How to Plant
Salad onions require well-drained soil rich in organic matter. Aim for a location that receives good sunlight and is somewhat shielded from wind.
Spacing
Flexibility is key when planting salad onions. Generally, a density of 250-350 plants per square meter is recommended, although interplanting allows for unique spacing arrangements.
How to Plant
Create a hole approximately 1-2cm deeper than the module and firm the module into the hole, allowing watering to naturally backfill over the following weeks.
Protecting and Supporting Your Plants
No formal support is needed, but fleece can provide protection during early spring. Autumn-planted salad onions can thrive outside if they are not overly exposed to wind.
Feeding and Watering
Onions benefit from consistent watering, about an inch every two weeks during dry spells.
Pruning and Management
No formal pruning is necessary, but thinning can be beneficial. For bulbing varieties, consider starting with 6-9 seeds per module and harvesting the larger plants in spring to allow remaining seedlings to mature into bulbs.
Harvesting
When harvesting, leave the roots in the soil for soil health and to avoid soil displacement around other interplanted crops. Clean harvesting can be achieved by pulling the plant up slightly and snipping the roots.
Freshly harvested salad onions provide exceptional crunch and vibrant greens. To maintain their quality, place the cut roots in a bucket of water immediately after harvest.
Storing
Salad onions store well in the fridge in airtight containers. The greens can be chopped into 1" lengths for salads or cooking, maintaining freshness for about a week.
Cooking and Eating
Best enjoyed fresh in salads, these onions can also serve as a delightful alternative to bulbing onions as they grow larger in late spring.
Dealing with Pests and Diseases
Salad onions are less susceptible to onion fly due to their harvesting schedule. However, protective fleece or nets can help, along with the use of specific nematodes for added protection.
While diseases are rare, some issues, such as fungal growth, can occur in wet and humid conditions. Cleaning up any affected plants is essential, but typically the overall harvest remains unaffected.
Removal of Plants
When the time comes to remove the plants, simply snip or slice off the roots and leave them in the ground.
What to Plant Before and After
Salad onions work well interplanted with lettuce, beetroot, spinach, and garlic, typically following peppers, tomatoes, winter squash, and brassicas.
Interplanting Strategies
For successful interplanting, salad onions should ideally be twice the height of companion plants to ensure they can compete effectively. This method enhances aesthetics and supports better growth for both plant types.
Wellies and Waxjackets emphasizes that interplanting involves thoughtful selection rather than random placement. Factors to consider include nutrient access, pest protection, root depth, growth rates, and mutual benefits, all aimed at creating a thriving garden ecosystem.
