Growing Korean cucumbers from seeds is a great way to add a tasty new addition to your garden.

Our expert gardeners will reveal the secrets to a bumper crop of this delicious treat in this growing guide. Here’s what you need to know.

What are Korean cucumbers?

Korean cucumber, also known as oi (오이) in Korea, is an Asian cucumber variety developed in South Korea. The fruit’s size is longer and more slender than that of regular cucumbers, typically around 18 inches (45 cm) long and 2 inches (5 cm) wide.

The skin is usually dark green, with small, spiky bumps. The flesh is pale green or white, with tiny seeds, crunchy texture, and a mild, fresh taste. Korean cucumbers are often burpless, and you can use them for both pickling and slicing.

– Different types of Korean cucumbers

In South Korea, cucumbers are such a popular vegetable that there are over 500 cultivars and hybrids available for sale. Korean cucumbers are very versatile indeed, and some varieties can even have white or stripy skin.

There are three main types of Korean cucumbers:

  • Baekdadagi: the most popular variety, it has a thin skin, with a juicy, crunchy texture;
  • Gasi: thin, dark green fruits with a spiky skin, this variety is best enjoyed fresh;
  • Nakhap: although it’s not as popular outside Korea as the Baekdadagi type, it is high-yielding and immensely enjoyed.

Korean cucumbers are a vining, annual plant, best grown as a summer crop. Although they grow in a tropical and subtropical climate in their native range, they can make a fine addition to vegetable gardens worldwide.

Ready to start planting your own? Here’s what you’ll need to get started.

How to plant cucumber seeds

Before you start planting your Korean cucumbers, it is essential to soak the seeds in advance to speed up germination time. You can either soak the seeds by spreading them out on moist paper towels or soaking them in a glass of lukewarm water. Soak the seeds for at least 12 hours, regularly changing the water or keeping the paper towels damp.

After soaking the cucumber seeds, you can start sowing them in seedling trays. When starting vegetables indoors, we prefer using compostable seedling pots rather than plastic trays. These pots help retain soil moisture better without ‘drowning’ the seeds. They also make transplanting the delicate seedlings much more straightforward, without damage to the roots or stems.

– Ideal conditions for germinating seeds

We suggest using compostable seedling pots that are at least 2 inches (5 cm) wide for Korean cucumber. Fill each pot with a seed starter and potting soil mix, make a shallow dip in the middle, place the seed inside, and cover with a thin layer of soil.

Use a spray pump to mist the pot, then put it in a warm and sunny spot. Korean cucumber seeds germinate in temperatures of at least 68 °F (20 °C). However, they can germinate in as early as three days if the temperature is around 90 °F (32 °C).

– When to transplant

Korean cucumber seeds usually germinate between 7 and 10 days after planting them. It is vital that you keep the soil moist but not soaked the entire time and keep them in a warm room. Once the seeds have sprouted, wait until each plant has 3 or 4 sets of leaves before transplanting outdoors.

– Outdoor Grow Tips

You can plant your Korean cucumber seedlings outside once soil temperatures consistently stay above 60 °F (15 °C). The young plants are susceptible to cold weather.

Our recommendation is to wait until late spring, or at least two weeks after any chance of frost has passed, before transplanting. To minimize the shock, you can acclimatize the young plants by moving the pots outdoors for a few hours each day. Make sure to bring them back inside during the night!

While your Korean cucumber seedlings are growing strong enough to plant outdoors, you can start preparing your garden for them.

  • Location

Korean cucumbers are tropical and subtropical plants, and they need a lot of light and moisture to grow. Pick a part of your garden that receives at least 6 hours of full sun each day.

Cucumbers can be grown in partial shade, although the plants won’t be as vigorous and will have a smaller yield. Also, there’s a higher risk that they will develop fungal problems when grown in the shade instead of full sun. The best temperature for growing Korean cucumbers outdoors is 70 °F to 86 °F (21 °C to 30 °C).

  • Soil

Prepare the soil by digging it up to a depth of 1 foot (30 cm), taking the time to turn it, and remove any debris such as rocks, branches, or weeds. Make sure to use plenty of soil amendments to improve drainage and incorporate plenty of organic fertilizers, such as compost. Korean cucumbers prefer growing in rich, well-draining soils, with a pH ranging from 6.5 to 7.5.

  • Support

Do Korean cucumbers need a trellis? Honestly, we recommend it.

Cucumbers are trailing plants, often producing vines up to 6 feet long (1.8 meters). Some cucumber varieties can indeed be grown as creepers without any climbing support.

However, Korean cucumbers produce long fruit that develops better when allowed to hang on the vine. Make sure to set up a trellis or other type of support system after preparing the soil.

  • Spacing

Plant your Korean cucumber seedlings at least 1 foot (30 cm) apart, and use the same spacing if you’re growing them in rows. By leaving sufficient space between the plants, you are ensuring healthy vine growth and allowing air circulation, which helps with pollination while reducing the chance of fungal diseases.

  • Watering

Water your Korean cucumber’s seedlings deeply after you have transplanted them. Keep the soil moist throughout the growing season, but avoid overwatering the plants. Cucumbers love moisture, but they are susceptible to root rot.

  • Pruning

Korean cucumbers are fast-growing plants and will reach 6 feet (1.8 meters) in height in about a month if the growing conditions are right. Check the plants every day, and use a pair of gardening scissors to trim off the side vines. These cucumbers bear fruit on the main vine, and regular pruning encourages the growth of flower-bearing vines.

  • Fertilizer

After the cucumbers have started flowering, we recommend applying a liquid fertilizer solution. A 10-10-10 nutrient ratio will work but avoid nitrogen-rich fertilizers, stimulating vegetative growth (leaves and vines) instead of flowering. Repeat the fertilizer application once every three weeks until late summer or until the plants stop growing new flowers.

  • Pollination

Should you manually pollinate Korean cucumbers? Although these plants are self-pollinating, giving them a hand (quite literally) will significantly improve fruit setting chances.

Suppose you’re growing cucumbers in a greenhouse. In that case, manual pollination is a must, given the fact that there is minimal airflow to move the pollen from the male flowers to the female ones.

Manually pollinating cucumbers is very easy. Start by identifying the female flowers: they should have a small lump on the flower stem, which will grow into the actual cucumber fruit after pollination.

Then, pick a male flower, remove the yellow petals, and gently rub it against the female to transfer the pollen. If pollination is successful, the female flower will wilt and dry out, and the small lump on the stem will grow into a cucumber in a matter of days.

– Harvesting time

Korean cucumbers usually take between 55 and 75 days to grow. Some hybrids, however, have been developed to bear fruit as early as 30 days after the seedlings have been transplanted. Make sure to check the manufacturer’s specifications on the seed packet to determine when your cucumbers will be ready.

How do you know that a cucumber is ripe? The average Korean cucumber’s size is around 18 inches (45 cm), so look for fruit that has reached that length and feels firm to the touch. Don’t worry about picking the ones that are a bit small. Korean cucumbers are best when they’re not fully ripe, so don’t leave them on the vine for too long, as this can make them turn bitter.

Korean cucumber plants are very high-yielding, so make sure to check them every day for fresh, new cucumbers. Once harvested, you can keep them in the vegetable drawer of your fridge for up to 5 days, covered in plastic wrap.

Cooking with Korean cucumbers

You can use Korean cucumbers for both slicing and pickling. Their flavor is mild and slightly sweet. The flesh has high water content, yet it has a crisp and crunchy texture, with tiny, pale cream seeds.

Unlike other cucumber varieties, they don’t have that typical bitter taste and are also easier to digest. Their skin is thin and does not need to be peeled off, as it is an excellent source of vitamins A and C.

Like most Asian cucumbers, the Korean variety is best enjoyed raw in salads or as garnishes. In Korea, they are often used to make oi muchim. This fresh cucumber salad uses sugar, vinegar, garlic, and chilies. Oi-bokkeum, or stir-fried cucumbers, is another great recipe, or if you’re in the mood for something with a bit of spicy tang, you can use them to make some delicious kimchi.

Conclusion

Not only do Korean cucumbers taste stunning, but they’re just as easy to grow as traditional varieties. With this guide, you should be able to produce a bountiful harvest in your garden.

Let’s go over the essentials:

  • There are many varieties of Korean cucumber, but they mostly share similar characteristics, such a sweet taste;
  • When growing Korean cucumbers from seeds, it’s best to soak the seeds before germination;
  • Germinating indoors before transplanting outside is a beautiful way to get a head start and enjoy a plentiful crop;
  • Top growing tips include providing a trellis for support, pruning side branches, and manually pollinating your Korean cucumber flowers.

Now that you know how easy it is to grow these sumptuous snacks at home, why not grab a pack of seeds and try it yourself? For a splash of variety, try 2 or 3 different cultivars!

Evergreen Seeds