When To Plant Onions In Ny

If you’re wondering when to plant onions in NY, you’ve come to the right place. Getting the timing right is the single most important step for a succesful harvest. New York’s varied climate, from Long Island to the Adirondacks, means planting dates can shift, but the core principles remain the same. This guide will walk you through the best planting times for onions in your specific area.

This heading is your golden rule. For most gardeners across New York State, the best time to plant onions is in early to mid-spring. The exact window depends heavily on whether you’re starting from seeds, sets (small bulbs), or transplants, and your USDA Hardiness Zone. Onions are cool-season crops that thrive when they get a head start in cool soil.

Understanding Your New York Growing Zone

New York spans zones 3b through 7b. This range creates a planting schedule difference of several weeks. Check your zone first to personalize the advice.

Zones 3b-5a (Upstate, Northern NY, Adirondacks): Plant late April to mid-May. Soil must be workable, not frozen or soggy.
Zones 5b-6b (Hudson Valley, Capital Region, Central NY): Plant mid to late April. This is a very common range for much of the state.
Zones 7a-7b (NYC, Long Island, Lower Hudson Valley): Plant as early as late March through April. These areas have the longest growing season.

Planting by Onion Type: Seeds, Sets, or Transplants

Your chosen method changes your start date significantly. Here’s how each one works:

Starting Onions from Seeds Indoors

For the widest variety, start seeds indoors. This method requires the most lead time but offers the best results for long-day onions, which New York growers need.

Start seeds 10-12 weeks before your last expected spring frost date.
For zone 5, this means sowing seeds in flat trays around late January to early February.
Keep seedlings under grow lights, trimming them back to 3 inches tall to encourage strong root and bulb development.
Harden off seedlings for 7-10 days before transplanting them outside in your spring planting window.

Planting Onion Sets (The Easiest Method)

Onion sets are small, dormant bulbs from the previous year. They are the simplest way to grow onions and are less suseptible to disease. Plant them directly in the garden 2-4 weeks before your last frost date. In zone 6, this is typically early to mid-April. Push them into the soil so just the tip is showing, spacing them 4-6 inches apart.

Using Transplants

You can purchase bunches of bare-root onion transplants from garden centers. These are essentially started seedlings. Transplant these into your garden 4-6 weeks before your last frost date, as soon as the soil can be worked. Handle the delicate roots gently when planting.

Seasonal Planting Guide for New York

Spring Planting (The Main Event)

This is your primary planting season. The goal is to get onions in the ground as soon as the soil is no longer frozen and has dried out enough that it doesn’t clump. A good test is to squeeze a handful; if it crumbles, it’s ready. If it forms a ball, wait a week.

Prepare the bed with plenty of compost and a balanced, slow-release fertilizer.
Ensure the planting site gets full sun—at least 6-8 hours daily.
Plant your chosen starts (seeds, sets, or transplants) following the spacing guidelines on your seed packet or set bag.

Fall Planting for a Head Start

In warmer parts of New York (Zones 6 and 7, especially Long Island), you can try fall planting for an earlier summer harvest. This is a more advanced technique and isn’t always reliable in colder regions.

Plant onion sets in late September to early October.
Choose a well-drained location and mulch heavily with straw after the ground begins to freeze.
The goal is for the sets to establish roots in the fall, survive the winter, and resume growth at the first hint of spring warmth.

Essential Tips for New York Onion Success

Beyond timing, these practices will ensure your onions thrive.

Choosing the Right Onion Variety

New York’s long summer days require long-day onion varieties. These varieties bulb up when they receive 14-16 hours of daylight, which our summers provide. Short-day onions will not form good bulbs here. Some excellent long-day choices include:

‘Copra’ (Excellent keeper)
‘Patterson’ (Great for storage)
‘Ailsa Craig’ (For large, sweet bulbs)
‘Red Wing’ (A reliable red storage onion)

Soil and Sun Requirements

Onions need loose, fertile, and well-draining soil. They hate wet feet. Work in 2-3 inches of compost before planting. A soil pH between 6.0 and 6.8 is ideal. Full, direct sun is non-negotiable for good bulb formation.

Watering and Fertilizing Schedule

Consistent moisture is key, especially during bulb formation (late spring/early summer). Water deeply when the top inch of soil feels dry. Avoid overhead watering to prevent foliar disease. Feed with a nitrogen fertilizer early in the growth cycle, but stop feeding once the bulbs begin to swell to encourage proper maturation.

Common Mistakes to Avoid in NY

Planting too late: Onions that don’t get established in cool weather often produce small bulbs.
Using the wrong type: Planting short-day or intermediate-day varieties in NY will lead to disappointment.
Poor weed control: Onions have shallow roots and can’t compete with weeds. Mulch lightly with straw or grass clippings.
Leaving them in wet soil: Raised beds are a fantastic solution for areas with heavy clay soil, which is common in parts of the state.

Harvesting and Curing Your Crop

Your onions are ready when the tops turn yellow and begin to fall over. Gently lift them from the soil. To ensure they store for months, you must cure them properly. Lay them out in a single layer in a warm, dry, airy place out of direct sun—like a garage or covered porch—for about two weeks until the necks are tight and the outer skins are papery.

FAQ: Planting Onions in New York

What month do you plant onions in NY?
For most of New York, the primary planting month is April. In colder zones (3-5), aim for late April to May. In warmer zones (6-7), you can start in late March or early April.

Can I plant onions in the fall in New York?
Yes, but with caution. It works best in zones 6b-7b (e.g., Long Island, NYC). Plant sets in early October and protect with heavy mulch. Success is less guaranteed than spring planting.

How late is too late to plant onions in NY?
If you plant after late May, the bulbs likely won’t have enough time to size up properly before the summer heat triggers bulbing and then dormancy. Early to mid-May is the latest advisable date for most areas.

What are the best onions to grow in NY?
Stick to long-day varieties like ‘Copra’, ‘Patterson’, ‘Yellow Sweet Spanish’, and ‘Red Zeppelin’. These are bred to perform under our specific summer daylength conditions.

Do onions need full sun in New York?
Absolutely. They require a minimum of 6 hours, but 8 or more is ideal for strong growth and large, healthy bulbs. Less sun leads to smaller bulbs and increased disease risk.

By following these guidelines for when to plant onions in NY, you’ll give your crop the best possible start. Remember, the cool spring weather is your ally. With good timing, the right variety, and proper care, you’ll be harvesting a bounty of homegrown onions that will store well into winter. There’s nothing quite like the satisfaction of pulling a firm, perfect onion from your own garden soil.