When to Plant Onions in Zone 7 for a Bumper Harvest

Written by

William Golder


Dorian Goodwin

when to plant onions in zone 7

Though they are cool-season crops, onions can grow within hot regions of the United States, such as hardiness zone 7. If you plan to cultivate this vegetable in your garden, it’s best to sow seeds or bulbs from January to March or September to December, though note that fall is a better growing season than spring.

Discover more tips on when to plant onions in zone 7 below.

Best Time to Plant Onions in Zone 7

1. Plant in spring and fall


There are two ways people generally grow onions: from seeds or bulbs. Regardless of which method you choose, follow these guidelines.

  • Sow seeds indoors eight to ten weeks before the last frost or outdoors six to eight weeks before the first frost. If you opt for spring planting, harden the onion off for one week before moving it outside.
  • As for growing onion bulbs, four to six weeks before the first frost or four to six weeks before the last frost will do. You don’t have to worry about the weather outdoors harming your plants in these cases, but note that 50℉ is ideal for optimal growth.

In any case, look up your frost dates and do some simple calculations. Since zone 7 has its final frost on April 15 and its first frost on October 30 on average, the best time for planting is as follows.

  • February 5 – 19 for indoor seeding or September 4 – 18 for outdoor seeding.
  • September 18 to October 2 or March 4 to 18 for those who plant onion bulbs

That said, you may also plant onion sets and seeds outside of these months.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Plant           Plant (fall planting is better as cool temperatures enable quicker germination and bigger bulbs.)

2. Planting time for different states


Here is zone 7 gardening time for onions in different states. As a quick reference, you can refer to the USDA zones map to see which climate area you’re in.

Zone 7 in Planting time
New Jersey April 1
Maryland April 7
Oklahoma February 15 to March 10
South Carolina (in zone 7b) February to March
September and November
Texas February 15 to March 10

3. How late is too late to plant onions in zone 7?


You can use the first frost rule above to determine your final planting time. Usually, October is the latest month one can grow onions for zone 7a and 7b.

Varieties of Onions to Plant in Zone 7


1. Short-day onions

Short-day cultivars are ideal for zone 7 and higher hardiness regions, so they should be your top choice when planting onions. Examples of this type include Georgia Sweet, White Granex, Texas Super Sweet, and Texas Sweet White onions.

2. Day-neutral onions

When it comes to the best types of onions for zone 7, day-neutral varieties are the second-best choice if you can’t get your hands on short-day cultivars. These will grow in any hardiness region, and zone 7 is only slightly hotter than their optimal climates of zone 5 to 6.

Candy, Sierra Blanca, and Red Stockton onions are prime examples of this category.

3. What about long-day onions?

They are best avoided in zone 7 due to their cool weather requirements. These are more suitable for northern locations within zone 6 or lower and a spring planting.

If you compare long day vs short day onions, the former requires up to fourteen hours of daylight to form bulbs, while the latter will do well with just ten hours of sun exposure.

Day-neutral types are smack in the middle of these two categories, calling for about twelve hours of day length to produce onions.

Caring for and Harvesting Onions in Zone 7


Care for onions by giving them at least ten to twelve hours of sunlight per day and an inch of water per week.

Fertilize them at seeding time with a 0-20-0 fertilizer and a 21-0-0 supplement every month after planting up until four weeks before harvest. If you see blight and purple blotch on the onions, use fungicides like Daconil to save the plants. As for thrips, an insecticide like Diazinon will keep them in check.

Finally, harvest onions when the tops turn yellow and flop over. This usually occurs 80 to 120 days after planting, depending on whether you use sets or seeds. To collect bulbs, simply pull them up with a fork or shovel by digging around the plant bases, then dry the onions completely before storing them.

In case you only want scallions and not onion bulbs, harvesting may be possible within three weeks after sowing. Simply snip off the shoots from the bottom of the plant to harvest green onions.

Factors That Affect the Optimal Time to Plant Onions in Zone 7

From the details above, it’s clear that the planting medium determines when your onion planting season begins.

If you have trouble deciding between seeds or sets and bulbs, here are some facts to consider:

  1. Seeds take more time to establish than bulbs, which is why you must grow them about two to four weeks earlier.
  2. Seeds may have trouble germinating, but they are cheaper and often necessary for growing certain varieties that are unavailable as sets.
  3. Bulbs or sets are more likely to bolt, which means there’s a higher chance they’ll produce flowers and seeds instead of bulbs under extreme temperatures.

So, transplants are the way to go for growers who want a middle ground between these two options. Transplants are diverse in varieties while still being reliable and bolt-resistant. You only need to sow them four to six weeks before the last frost in spring.

Frequently Asked Questions

Can I grow onions from seeds in zone 7?

Yes. You can grow onions from seeds in zone 7 before last frost and first frost. Aside from planting onions in-ground, you may also keep them in pots measuring around 8 inches wide to harvest scallions or opt for containers with a width of 39 inches to grow multiple onion bulbs.

How often should I water my onions in zone 7?

Water them after sowing and about once a week thereafter, whenever the top one inch of the soil feels dry.


Knowing when to plant onions in zone 7 will help you produce a bountiful harvest of them once spring comes. Onions are relatively undemanding in terms of growing conditions, and they make for delicious bulbs that are nutritious at the same time, whether you’re making sweet or savory dishes.

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