Growing Onions

Onions thrive in sunny environments such as raised beds or rows. Their roots need light soil with no sandy, heavy clay or loam deposits – avoid using sandy, heavy clay or loamy varieties!

Onions are photoperiodic plants, meaning their growth depends on sunlight hours. Short-day onions require only 10-12 hours of sunshine in order to produce blooms.

Fertilize

Onions require regular nutrition throughout their growing season, especially nitrogen for green leaf growth, which supports bulb formation. For optimal results, use a balanced fertilizer such as 10-10-10 every 3-4 weeks as side dressing with ammonium sulfate is fast-acting nitrogen source. Incorporating organic matter like compost before planting will also enhance soil structure and its capacity to hold onto nutrients more readily.

Onion plants require cool, well-drained soil that’s rich in organic matter for maximum success. A soil test is the best way to assess if amendments need to be made; if necessary, add compost or well-rotted manure as required to improve conditions in your growing bed. Onions have shallow roots, making them susceptible to weed invasion. Weeds compete with onion plants for water and nutrients which leads to competition with them for water/nutrition intake; adding Treflan or corn gluten meal six weeks before planting will help control weeds while providing added moisture; additionally adding mulch layers made up of straw/organic material can also work wonders!

Start planting onion seeds, sets or transplants early spring when the ground is workable. Soak the seeds for 24 hours prior to sowing; or gradually harden off indoor-hardened transplants over several days prior to placing outside.

As onions develop, their roots push deeper into the soil and form bulbs. It is crucial that growing areas remain free of weeds and that nitrogen fertilization be stopped once bulbing has begun; using a balanced fertilizer such as 10-10-10 or organic compost-based blend will provide your onions with all of the essential nutrients.

Once bulbs reach maturity, their tops die and fall over, signaling harvest time. To prevent issues with rot forming, onions should be dried thoroughly before being stored shadily outdoors or warm basement/garage environment.

Thrips flies are known to occasionally infest onion plants. More likely though, they prefer crops near larger grains such as lima beans and wheat before moving onto onion plants after those crops have been harvested. To reduce infestations from such small grains such as these and rotate crops more regularly. If thrips fly infestation occurs on your onions, treat with insecticide immediately in order to limit their impact.

Weed Control

Weed control in onions is especially critical, due to their shallow roots which compete for water, nutrients and space with weeds that invade from other areas. Competition with weeds has been proven to decrease yield up to 96% (Bond & Burston 1996). For seeded onions, six weeks should be free from any significant weed competition before crop growth commences.

Onions are cool-weather crops and thrive best in sunny locations with rich, well-drained soil with a pH range between 6.0 to 6.8. If your native soil is poor, amend it with several inches of aged compost or other organic matter before planting your onions in rows that are 12 inches wide. Space them 6 inches apart along the rows to achieve optimal harvest results.

Before planting onions, using Treflan or corn gluten meal in the top inch of soil helps prevent weeds and maintain soil moisture levels. Furthermore, onions benefit from being protected with light layers of mulch like straw to provide extra insulation against hot temperatures.

Growing onions requires managing multiple pests, including weeds and fungal diseases like blight and purple blotch fungus diseases that appear as small white spots with greenish halo around their center, such as blight. Bed spacing that increases airflow within the canopy is beneficial in helping prevent this condition; if disease pressure increases significantly a fungicide application may be necessary.

Thrips thrips is an insect pest which appears as tiny yellow to brown specks on leaves and can damage onions by sucking their juices away, creating bitter onions with reduced storage quality and making harvest time difficult. Therefore, an integrated thrips management plan should form part of any onion growing plan.

Flumioxazin (Chateau 51 WDG) is approved in North Carolina for postemergence weed control on onions seeded dry-bulb style from two- to six-leaf stages and transplanted onions of three to six leaves. This product effectively controls winter annual weeds such as chickweed and henbit, along with some problematic summer annuals like common lambsquarters and pigweed species.

Dimethenamid (Outlook 6 EC) is approved in several states for preemergence weed control of onion seeds, seedlings and transplants up to four-leaf stage for transplanting, as well as direct seeded onions up to six-leaf stage for direct sowing – this product controls many annual grasses as well as broadleaf weeds such as common ragweed and pigweed species.

Water

Onions thrive best in well-drained soil that’s rich in organic matter. Depending on their variety, onion plants require six to nine inches of water per week for proper development; too little and the plants won’t grow; too much and they become susceptible to rot and disease.

Early growth stages for onion plants require full sun and should not be planted near other crops that also need strong sunlight or maturity before onions do (e.g. tomatoes). Onions are particularly susceptible to Thrips antiqua (Delia antiqua), an insect pest which feeds on sap from onions through rasping mouthparts that feed off its leaves; damage occurs via bulbs damaged due to storage rot, too. To combat Thrips antiqua, plant resistant/tolerant varieties and avoid planting near small grains like lima beans.

People sometimes make the mistake of cutting off onion plants at their neck or stem to encourage them to bulk up below ground, however this only delays bulb development as the bulb grows in its root area and feeds off sugars stored within its leafy green tops. When an onion plant reaches maturity it will stop producing new greens and its leaves will begin to die back naturally.

Overhead watering should be avoided for growing onions as this can increase the risk of fungal disease that attacks their roots. Employing an irrigation system or drip tape directly delivering water directly into the root zone is much healthier for both plants and reduces risks for disease outbreak.

Watering should take place early in the morning to allow your plants to dry before evening temperatures decrease and moisture remains on their leaves. If necessary, late in the day water should be done lightly to avoid leaving too much moisture in the soil throughout the night and help avoid fungal diseases like blight or purple blotch that affect onions.

Harvest

Onions thrive best in full sun, particularly early on in their development. Full sunlight also helps onion plants withstand diseases, like Fusarium basal rot and onion root maggots that affect other vegetable crops; both of these diseases can be managed using optimal growing conditions, including fertilizing with low-nitrogen organic fertilizers such as Treflan or corn gluten meal once every six weeks during their growing season raked into the top inch of soil every six weeks raked into their top inch by hand every six weeks; layering organic materials between onion plants can help prevent competition between competing weeds that compete for their nutrients from competing with onions’ own nutrients from competing for its nutrients from competing with each other in terms of appearance versus taste!

Onion plants must be harvested at the right time in order to maximize flavor and size from their bulbs, otherwise too early harvesting may result in immature bulbs (scallions). When lower leaves start withering and dying off, or when their tops turn yellow/brown and fall over, onion plants are ready for harvesting.

At harvest time, it is crucial that onion plants be pulled gently; otherwise they could break and prevent their bulbs from growing to their full potential. Also important: it should never be covered up after harvest as this could lead to seeds producing and bolting instead of maturing into full-sized onions.

To maintain optimal onion quality and longevity, they should be thoroughly dried prior to storage. To do so, allow them to air-dry either outdoors or in an unheated garage or basement space with good ventilation.

When it comes to growing onions, seed selection is of utmost importance. No matter if starting from seeds, onion sets or plants, planting the incorrect type will ensure failure of your onion crop. Onion seeds should only be planted if you have plenty of time for thinning and maturity before the weather warms up; onion sets (immature bulbs grown from seeds last year) provide quick coverage when it’s time for planting; however if storing is your goal then do not use onion sets – they won’t keep as long.