When to plant cucumbers: 4 options for a non-stop harvest

A just-picked cucumber is a summer treat and knowing when to plant cucumbers is the best way to give your vines a strong start to the growing season. Cucumbers are sensitive to cold temperatures and easily damaged if planted too early. Wait too long and there may not be enough time left in your growing season to mature the crop. There are several options for timing cucumber plantings with seeds started indoors or direct sown in garden beds. Below you’ll learn 4 options for when to plant cucumbers to ensure you enjoy months of crisp, flavorful fruits. 

Cucumber planting times

Why is it important for gardeners to know when to plant cucumbers? Cucumbers are heat-loving vegetables and easily damaged by cold temperatures or frost. If the seeds or seedlings are planted too early, the plants may be set back or killed. If you wait and plant too late in the season, the vines may not have enough time to mature and produce their crop of fruits before the weather turns cold.

When to plant cucumbers: 4 easy options

Cucumbers are grown from seeds planted directly in the garden, seeds started indoors, or from seedlings bought at a local garden centre. Here are the four options for planting cucumbers:

1. Starting seeds indoors – My first cucumber planting of the season is when I sow seeds indoors under grow lights. 
2. Transplanting seedlings outdoors – This is an excellent option for gardeners who want a head start on the cucumber harvest as well as those who live in short season climates.
3. Direct sowing seeds outdoors – Cucumber plants are fairly quick to go from seed to harvest with most varieties needing between 55 and 70 days of growth before they start to produce fruits.
4. Succession planting for a second crop – For the longest season of high-quality cucumbers, I direct sow more seeds about a month after my first planting.

You don’t have to use all of these options when planting cucumbers in your garden beds or containers. I typically start seeds indoors and then succession plant. Choose whatever works best for you. Below I’ll share all the details on each of these planting options and offer tips for success.

When to plant cucumbers: Option 1 – Starting seeds indoors

Cucumber seedlings are very quick to grow and should be started indoors only 3 to 4 weeks before you intend to harden them off and transplant them into the garden. Don’t start them inside too early! Overmature plants don’t transplant well and are prone to transplant shock. Here’s my strategy for knowing when to plant cucumbers indoors:

• Figure out timing – Cucumbers grow best with warm soil and air temperatures. The optimal temperature range for both seeding and transplanting is 70 to 85 F (21-30 C). This is typically one to two weeks after the last spring frost. That means you’ll start the seeds indoors 1 to 2 weeks before the last frost date. 
• Start the seeds – Once you know when to start the seeds, fill seeding trays or pots with a high quality seed starting mix. Sow cucumber seeds a 1/2 inch deep and place the trays or pots under a set of grow lights. Because cucumbers germinate best in warm temperatures I slip a seedling heat mat beneath the containers. Once about half of the seeds have sprouted I turn off the mat. 
• Hardening off – Start the hardening off process when the seedlings are about 3 weeks old. Hardening off, which acclimatizes the young plants to outdoor growing conditions, takes 5 to 7 days. 

When to plant cucumbers: Option 2 – Transplanting seedlings outdoors

If you started cucumber seeds indoors or purchased cucumber transplants from a garden centre, you need to know how to figure out when to move them to your garden beds. As noted above, cucumbers are tender plants and easily damaged by cold temperatures or frost. It’s tempting to rush the young plants into the garden as soon as the last frost date passes, but it’s best to wait until the weather is reliably warm. Daytime temperatures should be above 70 F (21 C) and night temperatures above 60 F (15 C). 

At that point you can transplant cucumber seedlings into garden beds or containers. Ideally, the cucumber plants should have 2 to 3 sets of true leaves. Overmature seedlings are prone to transplant shock, so be picky when selecting cucumber plants from a local garden centre. If the plants are root bound, turning yellow, or past their prime, don’t buy them. When transplanting cucumber seedlings, don’t disturb or break apart the rootball. Tuck the seedling into the soil, gently firm the earth, and water. Learn more about how far apart to space cucumber plants.

When to plant cucumbers: Option 3 – Direct sowing seeds outdoors

Cucumbers are easily grown from seeds direct sown outdoors. Using this technique means you don’t need to go to the extra step of starting the seeds indoors. As with transplanting, direct sow cucumber seeds when the last frost date has passed and outdoor temperatures have warmed. Ideally, the daytime temperature should be above 70 F (21 C) and nighttime temperatures shouldn’t drop below 60 F (15 C).

To direct sow cucumber seeds, plant the seeds a 1/2 inch deep and 10 inches apart, if planting in rows. I like to dig a shallow furrow or trench with a garden hoe. The rows should be 18 to 24 inches apart. If planting the seeds in low mounds or hills, plant 3 seeds in each mound and space the groups 18 inches apart.

When to plant cucumbers: Option 4 – Succession planting for a second crop

Succession planting is my secret to a non-stop harvest from mid-summer until frost. Knowing when to plant cucumbers for a successful succession crop is easy! About a month after I first seed or transplant cucumbers in late spring, I sow more seeds for a second crop. At this point in the season, the soil is warm and the seeds germinate quickly. By the time these new plants begin to produce cucumbers the early plants are slowing down and the quality of their fruits is declining. When planting a succession crop of cucumbers it’s important to make sure your growing season is long enough to mature the second planting. I usually pick an early-maturing variety like Marketmore which needs around 60 days to go from seed to fruiting. 

Another way to prolong the cucumber harvest is to plant several varieties with different days to maturity. For example, plant an early variety (like Marketmore or Sweet Success) and a later maturing variety (like Lemon or Armenian). 

The best site for growing cucumbers

Cucumbers are not hard to grow, but you’ll find the most success when you pick a site with full fun and rich soil. Look for a garden that offers 8 to 10 hours of direct sun each day. Before planting, I prep the site by adding an inch or two of rotted manure or compost. I also add a granular organic fertilizer to the garden. Cucumbers grow best in soil with good drainage and thrive when planted in raised beds. In-ground gardeners can boost drainage by planting cucumbers in hills or low mounds. 

Once the young plants are growing well, I use an organic mulch like straw or shredded leaves to cover the soil. This allows the soil to retain moisture and also reduces weed growth. If you want to make watering a snap, run a soaker hose beneath the mulch.

Do you want to learn more about when to plant cucumbers? Watch this video:

Cucumber growing tips

Now that you know when to plant cucumbers, I’ve got 5 tips to help you get more out of your cucumber patch:

1. Pre-warm the soil. Spring temperatures can be slow to warm up and pre-warming the soil is an easy way to prep a cucumber bed for planting. You can lay a sheet of black plastic on top of the soil, weighing it down with rocks or using garden staples to hold it in place. This is best done at least a week before you wish to direct seed or transplant. 
2. Fertilize. Cucumbers are heavy feeders and benefit from a steady supply of nutrients. I use a liquid organic fish or seaweed fertilizer every 2 to 3 weeks to give the plants a boost. 
3. Reduce pests. The best way to reduce cucumber pests like cucumber beetles, aphids, and other bugs is to use lightweight row covers. Float them on hoops over the bed for the first month or so. When the plants begin to flower, uncover the crop so bees can access the flowers for pollination to take place.
4. Hand pollinate. And speaking of pollination, I often hand pollinate cucumber flowers. This is easy to do and ensures plenty of fruits in the event of bad weather or few pollinators. To hand pollinate, use a small clean paint brush to transfer pollen from male flowers to female flowers. This is best done early in the day when pollen quality is high. 
5. Plant flowers. One of my pest-prevention strategies in the vegetable garden is to include flowers like cosmos, zinnias, and sunflowers to attract beneficial insects. 

5 of the best varieties of cucumbers:

Now that you understand when to plant cucumbers, here are some of my favorite varieties to plant this season:

• Diva – Diva is an award-winning cucumber variety that produces high-quality fruits that should be picked when 5 to 6 inches long. Expect crisp, sweet cucumbers and a large crop from each plant. 
• Sweet Slice – This is a slicer with 10 inch long fruits that have thin, bitter-free skin. The disease resistant vines can be grown up a trellis or let them sprawl along the ground. 
• Salad Bush – Salad Bush offers a good crop of 8 inch long slicing cucumbers produced on very compact plants. I like to grow this variety in pots or in my raised beds and support the short vines on tomato cages. 
• Lemon cucumber – I’ve been growing Lemon cucumbers for over 30 years and I’m still delighted by their unique round shape and mild flavor. The fruit of this heirloom variety should be harvested when they’re 2 to 2 1/2 inches across and still pale green. 
• Suyo Long – Originating from China, the vigorous plants of Suyo Long yield long, slender cucumbers up to 15 inches long yet just 1 1/2 inches across. Expect an outstanding bitter-free flavor that is delicious straight from the garden or slice the cucumbers for a batch of bread and butter pickles. 
• Bush Pickle – Bush pickle is an early, high-yielding, and delicious variety to plant if you want to make dill pickles. The vines are compact and grow just 30 inches long making this a good choice for containers. Harvest the crunchy fruits when they’re 4 to 5 inches long. 

For more information on growing cucumbers, be sure to check out these detailed articles:

• How to grow cucumbers in containers
• Cucumber trellis ideas to grow plants vertically
• Learn about the common diseases and pests of cucumbers
• Armenian cucumber: A heat-tolerant vegetable for the summer garden

I hope I answered your questions about when to plant cucumbers. Do you prefer to direct seed or start cucumbers indoors?