Far and away the best onion plant companions are members of the cabbage family, such as: Broccoli. Kale. Brussels sprouts.
Overall, onions are very good neighbors, however other onion plants such as leeks, garlic and shallots can attract onion maggots. Onion maggots travel easily from plant to plant, so planting these like species in near proximity can give these pesky pests a multi-lane highway throughout your onion patch.
Planting onions and garlic together won't have a drastic impact on either crop but it will have a big impact on those around them as like garlic, onions, chives and other members of the allium family repel many mites and grubs. Although garlic has many friends, it also has a few enemies.
Most onions require about 30 inches of water per season to grow a good crop with drip irrigation. The key is to provide about 0.3 – 0.4 inches/day – drip irrigation is the best way to apply small amounts of water frequently.
Feed your onions lots of nitrogen to increase bulb size. Because they are a root vegetable, many people believe that onions require lots of phosphorus, however, for increased onion size, nitrogen is your key nutrient. Each leaf that an onion plant produces means an additional ring on the onion.
Onion sets and onion plants require loose soil and should be planted early (end of February or March). Dig a shallow trench, working in compost or fertilizer for big onions. Likewise, raised beds can be implemented. Plant the onions about an inch deep and 4-5 inches (10-12.5 cm.)
Onions have a limited root system, so improving the soil with lots of organic matter before planting is invaluable – dig in a bucket of garden compost or well-rotted manure per square metre/yard. This will help add nutrients, improve the soil structure and hold moisture in the soil. Avoid using fresh manure.
Growing Onions On
The seedlings can now be grown on in the greenhouse or cold frame until they are ready for planting out in early to mid spring. One of the joys of starting onions in this way is that there is no need to thin out the resulting seedlings – they can be set out in clusters, exactly as they are.
Select healthy green transplants and plant them 1 to 1 1/2 inches deep in rows 12 to 15 inches apart. To produce large, dry onions, place the plants 2 to 3 inches apart.
Space the plants 4 to 5 inches apart in the row to produce large-sized bulbs (closer spacing significantly decreases bulb size) or space 2 to 2 _ inches apart and harvest every other plant as a green onion. Allow 12 to 18 inches between rows or space onions 6 to 8 inches apart in all directions in beds.
Don't plant them in the same location year after year, as this can encourage the spread of diseases that affect the crop. Learn more about crop rotation. Select a location with full sun, where your onions won't be shaded by other plants. The more energy they can get from the sunlight, the larger their bulbs can grow.
Onions require a high source of nitrogen. A nitrogen-based fertilizer (ammonium sulfate or ammonium nitrate) should be applied at the rate of one cup per twenty feet of row.
We concluded that chicken manure could be exploited in growing onions with health-promoting properties.
When you notice the leaves on the first few plants start to fall over, stop watering and leave the onions in the ground for 7 to 14 days (depending on how dry or humid your climate is) to allow them to finish maturing. Withholding water at this stage helps keep the onions from rotting.
Again, don't bury them more than 1 inch under the soil. It's important that onions aren't planted too deep, as this can affect bulb development.
Onions are heavy feeders, so make sure to provide plant food with plenty of nitrogen, phosphorus and ammonium sulfate. A good rule of thumb is to add one cup of equal parts blood meal and bone meal granule fertilizer every 10 feet of row.
Dig up any onions that produce a flower stem. Once they start to set seed they won't grow any more, and they don't store well either. But onions that have bolted are still edible and will taste fine, so dig them up first and eat them, leaving the others to mature in the ground.
Onions need a lot of water, but the soil should never get soggy. Ideal onion water needs are to irrigate to a depth of an inch (2.5 cm.) once a week rather than a light sprinkling each day.
As maturation proceeds, necks soften and the weight of the leaves causes the tops to fall over. "Tops down" is the physiological response that results from compounds shuttled from the onion's leaves to its scales; consequently, the bulb swells and the tops dry down.
Answer: All onions and leeks are biennial, meaning that they normally take two years to grow from seed, flower and set seed again. First, they grow “vegetatively,” forming roots, leaves and other plant growth.
In climates with long growing seasons, peppers and tomatoes also are good candidates for planting after garlic or onions. In cooler climates, Chinese cabbage or pak choi may be the perfect choice.