Watering onion plants successfully can be tricky. Too much or too little can cause problems. It’s a good idea to become familiar with the watering needs of onions so you can choose the best methods of irrigation.
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Onion plant watering can be a tricky business. Too little water and the size and quality of the bulbs suffer; too much water and the plants are left open to fungal disease and rot. There are a couple different methods for watering onions, however, so it’s a good idea to familiarize yourself with overall onion watering needs before deciding on the best course of irrigation for you.
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.
If you are watering onions with a hose or sprinkler, water in the morning rather than during the heat of the day, which will just end up being evaporated.
Overhead watering can spell trouble. If you water in the evening, the foliage will stay wet overnight, which can foster disease. There are two other onion plant watering methods, though, that can alleviate the problem with wet foliage.
Onions are a popular vegetable to grow in home gardens. With their pungent flavor, onions can elevate any dish. However growing tasty, large onions requires paying close attention to irrigation. Knowing how much water onions need and when they need it is crucial for success.
In this complete guide, we will cover everything you need to know about proper onion watering. We’ll discuss onion growth stages, general watering guidelines, signs of over and under-watering, and best practices for irrigating onions. Follow these tips for the best onion crop ever!
Onion Growth Stages and Water Needs
Onions go through three main growth stages, each with different water requirements
Onion Seedling Stage
- Lasts approximately 45-60 days after seeds are planted
- Seedlings need consistent moisture in the top 6 inches of soil
- Water 1 inch per week during this stage
Onion Bulb Formation Stage
- Lasts approximately 45-60 days after the seedling stage
- This is when the onion bulb begins to swell and expand
- Water needs increase to 2 inches per week
Onion Maturation Stage
- Lasts approximately 15-30 days before harvest
- Watering can decrease to 1.5 inches per week
- Stop watering completely 1-2 weeks before harvesting
General Onion Watering Guidelines
- Space onion plants 4-6 inches apart in rows 1-2 feet apart
- Plant onions 1/2 inch deep
- Onions need approximately 1 inch of water per week
- Water deeply and infrequently, around once a week
- Water at soil level, avoid overhead watering
- Stop watering once onion tops start to fall over, about 2 weeks before harvesting
How Often to Water Onions
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Water onions about once per week, providing 1 inch of water
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Adjust frequency based on soil type, weather and growth stage
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Sandy soils will require more frequent watering than clay soils
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Hot, dry weather increases water needs
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More water is needed during bulb formation stage
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Stick your finger 1 inch into the soil to check moisture before watering
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If soil is dry, it’s time to water
Onion Watering Methods
There are several effective methods to properly irrigate onions:
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Hand Watering: Use a hose or watering can to manually water onions at soil level. Avoid overhead watering which can promote diseases. Water in morning so foliage dries quicker.
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Drip Irrigation: Most efficient method, provides water directly to roots. Use drip tape buried 2-4 inches deep, with emitters every 12 inches. Moisture is consistent with less water lost to evaporation.
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Furrow Irrigation: Channels or furrows are dug between onion rows. Furrows are flooded with 1-2 inches of water, allowing it to soak into soil. Avoids wetting foliage, reducing disease risk.
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Sprinkler Irrigation: Set up sprinklers or impact sprinkler heads between onion rows. Water early in day so foliage dries quickly. May be less efficient than drip or furrow irrigation.
Total Onion Water Needs
Onions have relatively high water demands. Total seasonal water needs vary by climate and variety:
- Short-day onions need approximately 18-24 inches of water
- Long-day onions need about 24-30 inches of water
Track rainfall and irrigation to ensure adequate water through each growth stage.
Signs Onions Need More Water
Watch for these signs your onions may be under-watered:
- Soil is dry 1 inch below surface
- Onion tops appear shiny, curled or wilted
- Stunted onion growth
- Small onion bulbs
- Pale or yellowed onion leaves
Signs of Over-Watering Onions
These indicate your onions may be getting too much water:
- Soil is soggy or stays wet for days after watering
- Soft onion bulbs
- Mushy roots or root rot
- Fungal leaf diseases like downy mildew or botrytis
- Onion bulbs with delayed maturity, thick necks
Best Practices for Onion Irrigation
Follow these tips for success in watering onions:
- Choose well-draining soil and raised beds if possible
- Mulch around onions to retain moisture
- Irrigate based on soil moisture, not a fixed schedule
- Water thoroughly, moisture should penetrate 6-12 inches deep
- Avoid overhead watering methods that wet foliage
- Stop watering once tops start falling over before harvest
- Provide supplemental water during dry spells
Proper irrigation, adapted to your soil and climate, is key for the best onion crop. Monitor soil moisture and growth stage, and adjust your watering accordingly. With good moisture management, you’ll enjoy thriving, productive onion plants.
How to Irrigate Onions
Two other methods for onion plant watering, besides using a hose or sprinkler, are furrow irrigation and onion drip irrigation.
Furrow irrigation is just what it sounds like. Furrows are dug along the length of the onion row and flooded with water. This allows the plants to slowly soak up the water.
Onion drip irrigation involves the use of a drip tape, which is basically tape with punched holes that deliver water directly to the roots of the plants. This method for watering onions eliminates the issue of fungal disease that can result from overhead watering.
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Install the tape in the center of the onion bed between rows at a depth of 3 to 4 inches (8-10 cm.) with emitter spacing about a foot (31 cm.) between emitters. Water occasionally and deeply; provide an inch (2.5 cm.) of water at each onion watering.
To tell if the plants have enough water, stick your finger in the ground next to the plants. If you can’t feel any moisture up to your first knuckle, it’s onion watering time.
How Often to Water Onions for Perfect Growth?
FAQ
How much water is needed for onions?
In most years, seeded onions should be irrigated 10 to 15 times during the growing season, applying 1.5 to 3 inches of water each time.
How much water do you give an onion?
Stick your finger into the ground near the plants; if you can’t feel moisture up to your first knuckle, it’s time to water. In a typical 12 week growing season, we recommend irrigating with one inch of water once or twice a week depending on the amount of rainfall received.
When should I stop watering my onions?
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UC Agriculture and Natural Resourceshttps://ucanr.eduHarvesting and Storing Onions from the GardenOct 4, 2021 — Harvesting Onions … Stop watering and fertilizing onions 7-14 days before harvesting to allow the onions to mature. When onions begin to mature, th…
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Onion Patchhttps://www.onionpatch.dixondalefarms.comSigns Your Onions are Ready for Harvest1. Soft Neck. When the area right above the neck (the place where the leaves meet the bulb) starts feeling soft, the transfer of carbohydrates from the leaves t…
