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For most gardeners, onion sets are planted in early spring for a summer harvest. But if you missed that window, you may be wondering if can still plant onions as late as July The short answer is yes, you can successfully grow onions when planted mid-summer, with a few considerations
In this comprehensive guide, we’ll look at how to select, plant, care for and harvest onions planted at the tail end of the traditional growing season With the right approach, you can enjoy a fall crop of bulbing onions from a late summer planting
Why Plant Onions in July?
Here are some of the main reasons you may want to put onions in the ground in the middle of summer:
- You missed the early spring planting window
- Wanting fresh fall onions for autumn recipes
- Experimenting with new onion varieties
- Had a crop failure and want to replant
- Growing onions specifically for storage over winter
- Simply want onions from your garden before next year
While yields may be lower from a mid-season planting, you can absolutely get a usable onion crop before winter arrives.
Choosing the Best Onion Variety for July Planting
For a successful late crop, choose the right onion variety adapted to your climate and daylight hours.
Day Length
Onions are classified by the number of daylight hours needed to initiate bulb formation. Long-day varieties need 14+ hours of sun, while short-day types bulb with just 10-12 hours.
For July plantings, short to intermediate day onions are best, as summer day length is decreasing. Common types include:
- Candy
- Granex
- Red Burgundy
- Stuttgarter
Check seed packet or plant tag for maturity time and day length needs.
Days to Maturity
Select a short season onion that can form bulbs and be harvested before your first fall frost. Look for varieties maturing in 80-100 days.
Disease Resistance
Disease pressure increases later in the season, so pick onions labeled as resistant to common problems like downy mildew, pink root and leaf blight.
Regional Suitability
Talk to local gardeners or your extension office to learn which onions grow best in your area when planted mid-summer. Heat and humidity tolerance is key.
Sourcing Onion Plants in July
You have a couple options for obtaining onions in the middle of summer:
Buy Sets or Transplants – Check local nurseries, hardware stores and garden centers for onion sets, plants or seedlings suitable for fall planting. Availability may be limited.
Start from Seeds – Begin seeds of fast-maturing onions 6-8 weeks before your planned July planting date. You can start them indoors or in a greenhouse.
Order Online – Many seed companies sell plants suited for summer onion planting. Just be sure to account for shipping days.
No matter your source, inspect onions closely for pest or disease problems before purchasing or planting.
Preparing the Planting Area
Since you’ve missed the early season, take time to prepare the planting area properly:
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Choose a sunny spot that gets 6+ hours of direct sunlight daily.
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Remove any existing weeds, plants or debris from the bed.
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Incorporate 2-3 inches of finished compost or well-rotted manure. Onions prefer nutrient-rich, fertile soil.
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Create raised planting rows or beds to improve drainage. Onions easily rot in wet soils.
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Water the area deeply a day or two before planting to pre-moisten soil. Don’t plant into dry ground.
How to Plant Onions in July
Here is a simple process for planting onions mid-summer:
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Separate onion plants or sets and select healthy, firm ones free of defects or damage.
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Create a planting trench 1-2 inches deep based on onion size. Space rows 12-18 inches apart.
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Place onions 2-6 inches apart in the trench based on expected mature bulb size.
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Cover onions with soil so just the tip tops show at the surface. Firm the soil around them.
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Water thoroughly after planting to soak the root zone 6-8 inches deep.
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Consider installing an irrigation system to provide consistent moisture.
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Mulch around onions after planting to retain moisture and reduce weeds.
Caring for Summer Planted Onion Crops
To help late planted onions size up properly, be diligent about care:
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Water 1-2 times per week during dry periods to keep soil moisture consistent.
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Weed regularly to eliminate competition, especially when plants are small.
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Side dress with a nitrogen fertilizer solution every 2-3 weeks.
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Use row cover fabric if cold fall weather arrives early.
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Monitor for diseases like downy mildew and remove affected plants promptly.
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Install bird netting over plants as bulbs enlarge near harvest time.
Closely monitoring weather and plant conditions allows you to respond quickly to the needs of mid-season onion plantings.
How to Harvest Onions Planted in July
Onions planted mid-summer mature quicker than spring plantings.
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Start checking bulbs in 60-80 days. Mine when 50% of the tops have fallen over.
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Gently lift bulbs with a garden fork, avoiding cuts or bruises.
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Allow onions to dry in the garden for 1-2 days before collecting them.
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Cut back tops to 1” and gather onions into mesh bags or vented crates.
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Cure bulbs in a sheltered, dry spot out of direct sun for 1-2 weeks.
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Store cured onions in a cool (50°F), dry location out of sunlight.
Onions don’t improve in size or quality after the leaves fall over, so try to harvest promptly before fall rains arrive.
Tips for Maximizing Onion Yields from July Plantings
To get the most from mid-summer onion plantings:
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Apply an organic bulb starter fertilizer at planting time to stimulate growth.
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Irrigate frequently to prevent soil moisture fluctuations that stress plants.
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Side dress with nitrogen every 2 weeks to fuel rapid bulbing.
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Monitor soil pH and keep around 6.0-6.5, ideal for nutrients availability.
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Control weeds aggressively so onions don’t have added competition.
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Use floating row covers at night if cold weather arrives early in fall.
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Harvest bulbs on schedule before colder temps or rain sets in.
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Cure bulbs for full 2 weeks at 65-70°F to maximize storage life.
Potential Problems with July Onion Plantings
Growing onions in the heat of summer can lead to some potential issues:
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Fast seeding – Some varieties bolt quickly if planting is delayed too long.
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Poor germination – Hot soils can prevent proper seed sprouting.
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Nutrient deficiency – Leached soils lack nutrients needed for good growth.
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Root maggots – Late plantings are prone to damage from onion maggot flies.
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Downy mildew – Humid conditions increase risk of this fungal disease.
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Sunscalding – Intense late summer sun can burn leaf tips.
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Dry soil – Extra irrigation is needed in hot mid-summer conditions.
Being proactive helps you avoid or minimize these potential problems.
While onions are traditionally early spring planted, you can still get a harvest from onions planted as late as July. Choosing short season, disease resistant varieties suited for fall planting is key, along with preparing planting beds properly. Extra care with watering, fertilizing, pest control and harvesting is also important. With the right approach, a July onion planting can provide bulbs for fresh summer meals or winter storage.
How to Plant Onions
Onion plants are heavy feeders and require constant nourishment to produce big bulbs. At planting time, add nitrogen fertilizer. Many organic gardeners will add an inch of compost to the bottom of each row before planting. Or, dig a hole in the ground that is about 2 inches deep and 3 inches wide. Then, add about an inch of compost to the hole and fill it back in.
- 2 to 6 inch gaps should be left between onion sets when you bury them. Press the sets gently into loose soil. (The closer spacing is best if you want to pick young onions as scallions.) ).
- Plants should be 4 to 5 inches apart, and rows should be 12 to 18 inches apart.
- Set the bulbs with the point end up. Once more, don’t bury them deeper than 2 inches. It’s important not to plant onions too deeply, as this can stop the bulbs from growing.
- Put straw between the rows as mulch to help keep the soil moist and stop weeds from growing.
Growing
It helps us to think of onions as a leaf crop, like kale or lettuce, instead of a root crop, like beets or carrots. Fostering healthy foliage growth ensures the plants have enough energy to form large bulbs.
- Covering young bulbs with light mulch will protect them, keep the soil moist, keep weeds away, and let air flow.
- Do not cover emerging onions.
- Fertilize every few weeks with nitrogen to get big bulbs. Don’t feed the onions anymore once they push the soil away and the bulbing process has begun. Do not cover the onions with soil again; the bulb needs to come up above the soil.
- If light mulch is used, onion plants usually don’t need to be watered all the time. It only needs about an inch of water per square foot per week, which includes rainwater. If you want sweeter onions, water more. To deter bolting, water them often during hot spells.
- To keep thrips away, plant onions next to tomatoes or carrots in rows that are very close to each other.
See our video demo to see how to plant and grow perfect onions! Recommended Varieties
Onions are photoperiodic (sensitive to daylight), so different varieties have been bred for varying day lengths. The border between long- and short-day varieties lies roughly at 36 degrees north latitude (the 36th parallel). North of that, plant long-day types; south of it, plant short-day onions. Or, try “day-neutral” (intermediate) varieties, which yield an excellent crop anywhere, regardless of day length.
Long-day varieties:
- ‘Yellow Sweet Spanish’: large, round shape; yellow-white.
- ‘First Edition’: high-yielding, stores well, flavorful, creamy-yellow
- ‘Red Wethersfield’: flat bulbs that store well, white flesh, red-skinned
- ‘Aisa Craig,’ ‘Walla Walla’: huge bulbs
- ‘Buffalo,’ ‘Norstar’: produce early but keep only until late December
- ‘Copra,’ ‘Southport Red Globe,’ ‘Sweet Sandwich,’ ‘Yellow Globe’: keep well
- ‘Red Florence’: oblong shape
Short-day varieties:
- “Stuttgarter”: sold in sets, yellow, pre-mature, and a little flat.
- ‘White Bermuda’: extremely mild, with thick, flat bulbs; white
- “Red Burgundy” is a good table onion with a mild, sweet white inside that won’t last long.
- “Crystal Wax White Bermuda” is a great onion for pickling when it is picked when it is the size of a pearl.
- ‘Hybrid Yellow Granex’: sweet, Vidalia type
- ‘Southern Belle’: ruby-color throughout
- ‘Texas 1015-Y Supersweet’: stores well
Day-neutral or intermediate varieties:
- ‘Candy’: golden, thick-flesh, jumbo bulbs; stores well
- ‘Red Stockton’: large, red-ringed, white-flesh bulbs
- ‘Super Star’: large, sweet, white bulbs
Harvesting
Pull any onions that send up flower stalks. This means that the bulbs have stopped growing. These onions will not store well but can be used in recipes within a few days.
- Spring-planted onions tend to be ready for harvesting by mid-summer.
- As onions get older, their leaves (tops) turn yellow and start to fall off. Once that’s done, bend the tops down or even stomp on the leaves to make them ripen faster.
- Loosen the soil around the bulbs to encourage drying.
- Harvest by late summer in dry weather. (Onions picked when they are still wet don’t cure well and could go bad in storage.) ).
- When the tops are brown, pull the onions. Carefully handle them, because even the smallest bump will cause them to rot, both now and when you store them.
- Cut off the roots and about an inch or two from the tops of the onions. If you want to braid the onions together, leave the tops on.
Should I Grow Onions from Seeds or Sets?
We like planting onion sets instead of starting them from seeds because they grow faster and are easier to plant.
- Onion sets are small onions that are ready to eat in 14 weeks. They are more likely to grow than direct-sown seeds or transplants and can handle light freezes. You can buy onion sets at gardening stores. They look like small bulbs and grow into full-size bulbs when they’re ready. Pick onion sets with bulbs that are 3/4 of an inch in diameter; bigger ones tend to grow stiff necks and seeds.
- Of course, you can start onions from seeds, and in colder places (Zone 5 and below), you may even need to. To grow onions from seeds, the soil needs to be at least 50°F. This means that the onions should be started indoors about 6 weeks before they are moved to the garden. If you’d like to try this method, read our guide on how to grow onions from seeds.
Practice crop rotation with onions. Don’t plant them in the same spot every year, because that can help diseases that hurt the crop spread. Learn more about crop rotation. Read Next.
Select a location with full sun, where other plants won’t shade your onions. The more energy they can get from the sunlight, the larger their bulbs can grow. Mix aged manure or compost into the soil in the fall or early spring to improve texture. Ensure there are no rocks or debris. Soil needs to be well-draining and loose; compacted soil affects bulb development.
8 Crops You can Still Plant in July
When should I plant onion seeds?
We recommend planting onion starts (transplants) or sets in the ground no later than a month before your last frost for spring plantings. For fall plantings for a spring harvest next year, you can plant seeds in late summer (6-8 weeks before your first frost) or plant seeds or starts in early fall (4-6 weeks before your first frost).
Should you plant fall onions?
There are many advantages you get when you plant fall onions. Once you plant fall onions, overwinter them, and harvest onions in the spring, you’ll always have a bed or two of onions in the The biggest benefit I see is that I get big, juicy, sweet onions in April and May, several months before my other spring-planted onions will be ready to eat.
How do you grow onions in a garden?
There are several inexpensive grow lights that you can choose from that you can use year after year. Step 1 : Choose a planting site that receives full sun and has well-drained soil. On average, each onion plant will need at least 6 inches of space on either side. I plant my onions 6 inches apart within row, with 4 rows on a 30″ bed.
When should you plant onion bulbs outside?
Ensure there are no rocks or debris. Soil needs to be well-draining and loose; compacted soil affects bulb development. In spring, plant onion sets outdoors as soon as the ground can be worked, usually in late March or April, when temperatures are no longer likely to dip below 28°F (-2°C).