Onions are a versatile vegetable that can be enjoyed year-round. While they are typically planted in early spring, many gardeners wonder if onions can be planted successfully later in the summer. Specifically, is July too late to plant onions and still get a harvest before winter?
The answer is yes you absolutely can plant onions in July! While it may seem strange to put onions in the ground during the heat of summer with the right approach you can still enjoy fresh bulbs from a late season planting.
In this detailed guide we’ll cover everything you need to know about planting onions in July including
- Why you may want to plant onions mid-summer
- Choosing the best varieties for July planting
- Preparing your soil and planting area
- When and how to plant the onion sets or seeds
- Caring for summer-planted onions
- Harvesting and storing your fall onion crop
- Maximizing yields from a late planting
- Troubleshooting potential problems
Why Plant Onions in July?
While onions are traditionally early spring planted, there are several good reasons you may want to put them in the ground later in the summer
- You missed the early spring planting window and still want onions this year
- You want fresh bulbs for fall recipes
- You want to experiment growing different onion varieties
- You had an unsuccessful early crop and want to replant
- You want to grow onions specifically for winter storage
- You simply want onions from the garden before next year
July plantings allow you to get a harvest before winter arrives, though yields may be lower than a spring planting. With the right approach, you can absolutely produce onions planted mid-summer.
Choosing Varieties Suited for July Plantings
To get the best results from planting in July, start by selecting varieties suited to late summer planting. The main factors to consider are:
Maturity Time
Look for early maturing varieties, ideally taking 80-100 days from planting to harvest. This ensures the onions can form bulbs before your first fall frost.
Day Length Sensitivity
Onions come in short, intermediate and long-day types. For July plantings, short or intermediate day length onions perform best as daylight hours are decreasing.
Disease Resistance
Choose varieties labeled as resistant to common onion diseases like downy mildew, pink root and leaf blight. Disease pressure rises later in summer.
Regional Suitability
Talk to local gardeners to learn which onions grow best in your area when planted in mid-summer. Heat and humidity tolerance are key.
Sources for Summer Onions
You can source onions for July planting from sets, transplants or by starting seeds 6-8 weeks before your target planting date. Order early maturing varieties online or check your local garden centers for availability. Carefully inspect all onions for signs of pests or disease before purchasing.
Preparing the Planting Area
Since you’ve missed the prime early season window, take time to prepare the planting area properly:
- Choose a spot getting full sun (6+ hours daily)
- Remove any existing plants, weeds or debris
- Incorporate 2-3 inches of aged compost or manure
- Create raised beds or rows to improve drainage
- Water area deeply 1-2 days before planting day
Onions need well-drained, nutrient rich soil, so take steps to improve your planting site before sowing seeds or sets.
How to Plant Onions in July
Once your soil is prepped, it’s time to get the onions in the ground. Here’s a simple process:
- Separate sets or transplants and select only healthy, firm ones
- Create planting trenches 1-2 inches deep based on onion size
- Space onions 2-6 inches apart in rows 12-18 inches apart
- Cover with soil so just the tips are exposed
- Firm the soil, then water thoroughly after planting
- Consider mulching to retain moisture and reduce weeds
Aim for consistent spacing and soil contact to encourage good rooting and growth.
Caring for Summer-Planted Onions
To help your July onions size up properly, be diligent with care:
- Water 1-2 times per week during dry periods
- Weed regularly to reduce competition
- Fertilize every 2-3 weeks with a nitrogen solution
- Use row covers if cold weather arrives early
- Monitor for diseases like downy mildew
- Install bird netting as bulbs enlarge
Extra attention allows you to respond quickly to the needs of your mid-summer planting.
Harvesting Onions Planted in July
Onions planted in July mature faster than spring plantings. Begin checking bulbs in 60-80 days. Harvest when about 50% of the tops yellow and fall over.
To harvest:
- Loosen soil and lift bulbs gently with a fork
- Allow to dry in garden 1-2 days before collecting
- Trim tops to 1″ and gather bulbs into vented crates or mesh bags
- Cure bulbs in a cool, dry spot out of sun for 1-2 weeks
- Store cured bulbs in a dark, cool (50°F) location
Onions don’t improve in storage if left in the ground too long, so harvest promptly once the tops start going over.
Maximizing Yields from July Onion Plantings
To get the most out of a mid-summer onion crop:
- Start with an organic bulb booster fertilizer at planting time
- Maintain consistent soil moisture through frequent irrigation
- Side dress with nitrogen fertilizer every 2 weeks
- Monitor soil pH and keep around 6.0-6.5
- Control weeds proactively to reduce competition
- Use floating row covers if cold weather comes early
- Harvest promptly when bulbs are ready
- Allow a full 2 week cure time post-harvest
With attentive care, you can achieve decent yields from onions planted as late as July.
Potential Problems with Late Summer Onions
Growing onions in July can lead to some possible issues:
- Fast seeding or bolting in hot weather
- Poor germination in overly warm soils
- Nutrient deficiencies in leached soils
- Root maggot damage from insect pests
- Increased downy mildew disease pressure
- Sunscalding of leaves in intense heat
- Dry soils requiring extra irrigation
Being proactive and attentive helps avoid or minimize these potential problems.
While traditionally an early spring crop, onions can be planted successfully in July with the right approach. Choosing short season, disease resistant varieties suited to fall planting is key, along with preparing planting beds properly. Providing attentive care and promptly harvesting bulbs also ensures the best results. With the right techniques, a July sown onion crop can provide fresh bulbs for summer meals or winter storage.
Should I Grow Onions from Seeds or Sets?
Onions can be grown from seeds or sets.
- Onion sets are tiny onions that mature in about 14 weeks. They can withstand light freezes and have a higher success rate than direct-sown seeds or transplants. The onion sets look like small bulbs sold at gardening stores; they develop into full-size bulbs once they mature. Choose onion sets with bulbs 3/4 of an inch in diameter; larger ones tend to produce stiff necks and go to seed.
- Onions grown from seed require the soil to be at least 50°F to germinate, so these should be started indoors about 6 weeks before transplanting to the garden.
In colder climates (Zone 5 and colder), many gardeners prefer starting from onion sets to onion seeds because you’ve jumpstarted the process. However, seeds are the most economical. Onion germination can be slow and patchy outdoors, so starting seeds indoors is recommended for cooler climates, not directly sowing outdoors. Growing from seed also allows you to choose more interesting and different varieties vs ordering onion sets. Check out our tips for growing onions from seed. Read Next
Onions need to grow in full sun and also in a spot where they won’t get shaded by other vegetables. 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.
In terms of location, practice crop rotation with onions. 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.
Planting or Transplanting Onions Outdoors
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 trench in the soil about 2 inches deep and 3 inches wide, and then fill the trench back in with about an inch of compost.
- If you are direct seeding outdoors, sow seeds in a 2-inch wide band, 1/4 to 1/2 inch deep, in rows 12 to 18 inches apart. After seedlings emerge, thin to 3 to 4 inches apart.
- If planting onion sets outdoors, bury them 2 to 6 inches apart, gently pressing them 1 to 2 inches deep into loose soil. (Use the closer spacing if you want to pull immature onions as scallions.) Don’t bury them more than 2 inches under the soil. Onions mustn’t be planted too deep, as this can affect bulb development.
- If you are transplanting, space 4 to 5 inches apart and rows 12 to 18 inches apart.
- Mulch with straw between rows to help retain moisture and stifle weeds.
We find it helpful to think of onions as a leaf crop (like lettuce or kale) rather than a root crop (like beets or carrots). Fostering healthy foliage growth ensures the plants have enough energy to form large bulbs.
- Ensure immature bulbs stay covered with light mulch to protect them, retain moisture, suppress weeds, and allow air circulation.
- Do not cover emerging onions.
- Fertilize every few weeks with nitrogen to get big bulbs. Stop fertilizing when the onions push the soil away, and the bulbing process has started. Do not put the soil back around the onions; the bulb needs to emerge above the soil.
- Generally, onion plants do not need consistent watering if light mulch is used. About 1 inch of water per square foot per week, including rainwater, is sufficient. If you want sweeter onions, water more. To deter bolting, water them often during hot spells.
- To deter thrips, intercrop onions with tomatoes or carrots in closely alternating rows.
See our video demo to see how to plant and grow perfect onions!
SIX Foolproof Onion Tips You Probably Didn’t Know You Needed
FAQ
Can you plant onions in July?
As far as temperatures go, onions (Allium cepa) are a hardy plant that can grow almost any time of year. Most folks plant them either in early spring for an early summer harvest, or many plant seeds in late summer or early fall for an overwintered spring harvest.
How late is too late to plant onions?
Most commercial growers will transplant their onions between Thanksgiving and Christmas. Weather and other factors can delay their planting, though. It isn’t unusual for growers to still be planting in January and even into February. Purchased transplants can be planted in January and February without any problems.
How hot is too hot for onions?
LIGHT: Sunny. (Green onions tolerate partial shade.) TEMPERATURE: Cool (45 to 60˚F) during development; Medium-hot (60 to 75˚F) during bulbing and curing. MOISTURE: Moist, but not waterlogged.
At what temperature do onions stop growing?
Onions can withstand frosts and moderate freezes, but you must shield them from hard freezes — that is, periods of at least four hours of temperatures below 25 degrees. They can survive temperatures as low as 20 degrees, but not for long.
How do you plant onions in the fall?
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.
When should you plant onions?
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.
How do you plant a July onion plant?
With the right approach, a July onion planting can provide bulbs for fresh summer meals or winter storage. 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.
How do you start a summer onion plant?
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.
Can you grow onions in summer?
Heat and humidity tolerance is key. 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.
How do you care for a July onion plant?
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. Onion plants are heavy feeders and require constant nourishment to produce big bulbs. At planting time, add nitrogen fertilizer.