How to Care for Your Onion Plant

Growing your own onions is fun and harvests are delicious. How do you care for an onion plant?

Onions are a versatile crop that’s always present in the kitchen. Because onions are easy to grow and store well, you can enjoy them all year. Some think homegrown onions have a certain sweetness that store-bought onions don’t. 

Please keep reading to learn when to plant onions and how to take care of them.

Why You Should Consider Growing It

Because onions are so versatile, they can be used to improve the flavor of any savory dish. Even the parts of the onion plant, particularly the leaves, that grow before the bulb are edible. 

Onions contain fiber and prebiotics, which are essential components of the digestive system. They have antioxidants that help reduce inflammation in the body and have also been proven to lower blood pressure.

Onions are an excellent crop to grow with other plants because their scent keeps pests like aphids, Japanese beetles, and rabbits away. Their skin is high in nutrients such as copper, iron, magnesium, calcium, nitrogen, phosphorus, and potassium.

newly harvest of white onion

General Care

Best Time to Plant

Onions are a hardy plant that can thrive almost all year round, regardless of temperature. Most onions are sown in the early spring and harvested in the fall when the tops begin to fade.

Many plant them in the early spring for a summer crop or in the late summer or early fall for a spring harvest the following season. 

growing onion sprouts planted in wet soil

Water Needs

Water once a week during hot weather. Although onions require a lot of water, the ground should never become soggy.  

Young seedlings need regular watering until they are fully established. When the bulbs reach maturity, consistent watering keeps the soil from compacting, allowing the bulbs to expand and grow easier.

Amount of Sun

Bulb onions require full sun to produce the best crop. Several onion varieties, however, can tolerate moderate shade. 

Short-day onion varieties develop bulbs after 11 or 12 hours of sunlight, while intermediate-day onion varieties need 12 to 14 hours. On the other hand, long-day onion varieties require 14 or more hours of light to grow bulbs properly.

growing spring onion in the garden


Onions require higher fertility levels than most other vegetables. They perform best in well-drained, slightly acidic, fertile soils in full sun. 

Heavy soils can be improved by incorporating organic matter, such as compost, into the soil or adding  2 to 3 pounds of fertilizer per 100 square feet of garden area.

Other Maintenance

Growing onions may seem challenging, but they’re one of the easiest crops for beginners.

Pruning seedlings when they are young is best for root and bulb development. Reducing the top green growth sends more plant energy into the roots and bulb. They grow more aggressively and produce more roots and larger bulbs. 

Additionally, the chopped green leaves of the onion can be added to food. They are an excellent addition to soups, casseroles, and other foods.

Alaine Connolly
Alaine has been working way too hard in horticulture since 1992, beautifying golf courses, resorts, and hotels. She is a part time landscape designer who works full time caring for a 28,000 square foot public garden. At home, she maintains her own 400 square feet plot. Alaine lives in northern Illinois - zone 5b.
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