When to Sow Cucumber Seeds in Your Zone

If you ask me, cucumbers are some of the most refreshing summer snacks. But if you want to be picking fresh cucumbers by the time hot summer days arrive, you have to plant your cucumber seeds at the right time. Planting too early brings a risk of cold damage, and planting too late means you’ll have to wait to harvest your cucumbers.

With all crops, the ideal planting date depends on where you live. Gardeners in zones two and three experience long, cold winters that dictate later plantings, while growers in zones ten and eleven can get away with earlier plantings. That’s why I’m going to cover when you should sow your cucumbers no matter where you call home.

Since cucumbers grow well when directly sown and transplanted, I’ll explain both methods. Planting your seeds at the right time sets you up for excellent plant growth and healthy harvests.

A Note About Growing Zones

Growing zones, also known as USDA plant hardiness zones, divide the United States into sections based on the average low temperature. Areas experiencing cold winters belong in lower-numbered growing zones, while those with warmer winters belong in high-numbered growing zones.

It’s important to recognize that hardiness zones only tell you about the average annual low. They don’t tell you the average last frost date, the high temperatures in the summer, or the number of frost-free days. However, you can use the hardiness zone to give you basic information about an area’s temperatures and frost dates.

For example, areas in lower hardiness zones tend to experience later spring frosts and shorter growing seasons, while areas in higher hardiness zones often experience earlier last spring frosts and benefit from longer growing seasons. However, two different cities located in zone eight can have average last frost days a month apart! Therefore, you should always consult historical data about your specific area when determining when to plant cucumbers and other cold-sensitive crops.

Keep Cucumber’s Sensitivity to Cold in Mind When Planting

You may already know that frost kills cucumber plants, but did you know that their seeds and seedlings are extremely sensitive to cold? The seeds are unlikely to germinate in soil that’s below 50°F (10°C), and their ideal germination temperature is 85°F (29°C)! The seedlings are also sensitive to air temperatures below 55°F (13°C).

Therefore, you shouldn’t set your seeds in the ground as soon as the danger of frost has passed. Instead, wait until the soil has warmed up and the air temperatures remain consistently above 55°F (13°C) at night. If you want to plant your cucumbers a bit earlier, make sure to use a floating row cover to protect the tender seedlings from cold nighttime temperatures.

When to Sow Based on Hardiness Zone

The following information will give you a good idea of when to plant your cucumber seeds, depending on where you live. If you’re not sure what hardiness zone you’re in, consult the USDA plant hardiness zone map.

Zone 3

If you live in parts of Montana, North Dakota, Maine, and other northern states, you may live in zone three. As one of the coldest growing zones in the continental United States, this zone experiences wintertime lows between -30 to -40°F (-34 to -40°C). That’s cold…really cold! These frigid temperatures coincide with long winters and late spring frosts.

Depending on where you live, you may experience your last frost at the end of May or the beginning of June. However, the soil and air won’t be warm enough to support cucumbers until a few weeks after the last frost.

If you want to plant directly in your garden, wait until the middle of June. You can start seeds indoors as early as June 1, then transplant them a few weeks later. Since areas in zone three typically experience their first fall frost sometime between the middle of September and the beginning of October, you shouldn’t plant cucumber seeds any later than the middle of June. 

That’s right; there’s no time for succession planting cucumbers here. But as long as you keep your cucumbers protected during cool weather and choose varieties with short days to maturity, you’ll be able to enjoy fresh cucumbers in zone three.

Zone 4

Areas in zone four experience winter lows ranging from -20 to -30°F (-29 to -34°C). Some spots located in this zone include parts of New England, the Rockies, and the Upper Plains. With these cold temperatures come short growing seasons and late spring frosts.

Since the last spring frost in zone four occurs sometime between the middle and end of May, you should wait until the middle of June to plant cucumber seeds outdoors. You can get a jump on the growing season by starting your seeds indoors in early June and transplanting the seedlings outdoors in mid-June.

Early fall frosts mean you’ll only have time for one succession of cucumbers. However, you can plant multiple plants in the middle of June if you want to enjoy a big harvest before cold weather arrives.

Zone 5

Growers in zone five can expect winter lows somewhere between -10 and -20°F (-23 and -29°C). Some locations in zone five include parts of Minnesota, Maine, and Colorado. Depending on which section of zone five you live in, you can expect your last spring frost to occur between early May and early June.

Since the last frost day varies throughout zone five, so does the time you should sow cucumber seeds. If you live in a location that experiences a last frost near the beginning of May, you can sow your seeds outdoors in mid to late May. However, if you don’t experience your last frost until the start of June, don’t sow seeds outdoors until the middle of June.

If you want to start your seeds indoors, you can do so around your last frost date. By the time the seedlings are large enough to plant outdoors, the weather will be warm enough to support their growth. I always recommend covering plants with row cover during their first week outside to help them acclimate to the colder temperatures and wind.

Zone 6

Zone six includes much of New England, the Mid-Atlantic, and the Midwest. Although all of these locations have an average winter low between -10 and 0°F (-23 and -18°C), they experience varying summertime highs and number of frost-free days. If you live in zone six, expect your last spring frost to arrive sometime between mid-April and mid-May and your first fall frost in October.

If you want to direct sow cucumber seeds, waiting until the end of May is a safe bet. However, if nighttime temperatures are forecasted to remain above 50°F (10°C), you can go ahead and sow your seeds sooner. Since your first frost won’t arrive until October, you can direct sow cucumbers up until the beginning of July.

Starting seeds indoors allows you to harvest cucumbers a few weeks earlier. Start seeds in mid-May and transplant outdoors two weeks later. Just make sure to be careful when handling the plant’s sensitive roots!

Zone 7

Zone seven spans from North Carolina across the Midwest and Great Plains and into parts of the Southwest and West Coast. Although areas in zone seven experience winter temperatures as low as 0 to 10°F (-18 to -12°C), temperatures don’t drop below freezing every winter night.

Depending on where you’re located in zone seven, you can expect the last spring frost to arrive sometime between mid-March and mid-April. The first fall frost typically occurs sometime in October or early November. With these dates in mind, you can figure out when to sow your seeds.

You can direct sow seeds in your garden anytime between late April and early July. Sowing one planting in early May and another in late June will give you a near-continuous supply of cucumbers throughout the summer. You can also speed up your first harvest by planting seeds indoors in early to mid-April and then transplanting them outdoors once temperatures remain above 50°F (10°C).

Zone 8

If you live in zone eight, you can expect winter lows to fall between 10 and 20°F (-12 and -7°C). Your last spring frost should arrive sometime in March or early April, and the first fall frost will typically occur in November. That means you have about seven frost-free months to work with!

Thanks to your long growing season, you can plant multiple successions of cucumbers. If you want to direct sow cucumbers in the ground, wait until the soil has warmed to at least 55°F (13°C). Depending on where you live in zone eight, this will occur sometime in late March or April. You can continue sowing cucumber seeds through early August.

If you want to transplant cucumbers, you can start them around your last spring frost date. By the time the seedlings are ready to plant outdoors, the weather will be warm enough to support their growth.

Zone 9

Areas in zone nine barely experience below-freezing temperatures during the winter. Air temperatures dip as low as 20 to 30°F (-7 to -1°C) but often remain above freezing during the winter.

Since zone nine includes diverse parts of the country, including southern Texas, northern California, and northern Florida, the last spring frost dates vary quite a bit. Some locations receive their last frost in mid-February, but others may experience frost up until late March. Therefore, it’s important to check the average last frost date in your area.

Once you have this date in mind, you can determine when to plant your seeds. You can sow your seeds outdoors a week or two after the last frost has passed, but there’s no harm in waiting a few extra weeks. Since zone nine experiences a long growing season, you can continue sowing cucumber seeds outdoors until the end of August.

Zone 10

Zone ten is reserved for the warmest parts of the continental United States. This zone includes much of southern Florida, Texas, and California. All locations in this area experience wintertime lows between 30 and 40°F (-1 and 4°C) which means they may never receive a frost!

Since zone ten is so warm, you can plant cucumber seeds there throughout much of the year. But remember that although cucumbers can survive in above-freezing temperatures, they won’t thrive if the air temperature drops below 55°F (13°C). Therefore, you should avoid growing cucumbers during the cool winter months.

If you live in zone 10, you can begin sowing cucumbers outdoors once nighttime temperatures remain above 55°F (13°C). In many areas, this occurs in February or March. Continue sowing new successions of cucumbers once a month until September.