A popular member of the vegetable garden, crunchy cucumbers freshly harvested from the garden are one of the joys of summer.
If you don’t like eating these nutritious fruits, you can also use them to flavor water or as part of your skincare regime. As the summer draws to a close, excess fruit can be pickled, enabling you to enjoy the fruits of your harvest throughout the dark winter months.
Many people purchase transplants from garden stores and enjoy cultivating their own cucumber plant either outside or in the greenhouse. But did you know that you can also learn how to plant cucumber seeds?
While planting cucumber seeds has a reputation for being difficult and prone to failure, it is not as hard as you may think.
Knowing how to plant cucumber seeds also enables you to enjoy a far wider variety than just what is on offer in your local garden store. Additionally, the skills learnt here can also be used to plant and grow other seeds.
This guide to how to plant cucumber seeds is designed to take you through the process from selection to harvest.
You can learn how to grow a cucumber plant from seed.
The first stage of learning how to plant cucumber seeds is selecting the right variety for your growing environment. In general cukes are divided into 2 groups, outdoor and indoor or greenhouse types.
Most cucumber seeds sold in garden stores are suitable for growing outdoors.
Outdoor cukes, also known as ridge cukes, can feel spiny or rough. Hardy specimens, outdoor types tolerate cooler climates and require less care than indoor varieties. Common outdoor varieties include:
- Marketmore 76,
- Tokyo Slicer,
- La Diva
- Mini Star
Outdoor types are long and bumpy.
Indoor or greenhouse varieties tend to produce smoother, longer fruits. These types require more warmth than outdoor types. They are best grown in a greenhouse or on a windowsill.
In warmer climates you can also grow your cukes outside in a sunny, sheltered part of the garden. Popular indoor varieties include:
- Marketmore AGM,
- Burpless Tasty Green,
- Emilie AGM,
- Carmen AGM.
Most cukes sold in garden stores are vining varieties. However, you can also find more compact, bush varieties. Commonly grown bush types include:
- Bush Pickle,
- Salad Bush,
- Bush Champion.
Most varieties of cuke are ready for harvest in 50 to 70 days,
When selecting a variety, take into account your growing position and climate. Selecting a variety, or varieties, that are suited to your space helps to make care a lot easier.
How to Plant Cucumber Seeds
Once you have selected your variety, it is time to learn how to plant cucumber seeds.
Before you begin, make sure that you have everything that you need to hand.
You will need:
- Seed starter pots,
- Watering can or hose,
It is best to learn how to plant cucumber seeds in their final growing position. Cukes are sensitive specimens that dislike having their root systems disturbed.
Learn how to sow seeds into their final growing position.
When to Sow
If you are learning how to plant cucumber seeds in a heated greenhouse sow anytime from late winter to early spring. Growers with unheated greenhouses should wait until mid-spring before sowing their seeds.
If you are growing outside, sow directly into the final growing position in either late spring or early summer. Allow the soil to warm up to 70 ℉ before starting. While you wait for the soil to warm up, use the time to work in any necessary amendments.
Sow seeds in prepared soil.
If you only enjoy a short growing season or want to get a head start, learn how to plant cucumber seeds in Baxrou Biodegradable Seedling Starter Pots. These can then be transplanted into the final growing position without the need to handle and disturb the roots.
As the pots break down, the growing roots are able to penetrate the sides and spread into the soil, supporting healthy growth above soil level.
You can start your cukes off indoors in pots in late spring.
Where to Sow
Your growing site should be a sunny spot with rich, well-draining soil. A neutral or slightly acidic soil is ideal.
There should also be enough room for your cuke to grow and develop without spacing out or overcrowding other vegetables. Bush varieties typically grow in mounds and require more space than vining types. However, they are unlikely to require staking.
Do not allow vining types to sprawl on the ground. This makes the cukes more susceptible to disease and the fruit more likely to rot. It is also a waste of space. Train your vining cukes to grow up and you can use the soil to plant another, low growing crop.
Train your cukes to grow upwards.
Herbs such as dill and oregano are good choices because they repel pests. You can also grow pollinator friendly flowers like nasturtiums or marigolds and root vegetables such as beets and radishes alongside your cukes.
How to Plant Cucumber Seeds
If you are learning how to plant cucumber seeds directly into their final growing position, sow the seeds of vining types 1 inch deep. Moisten the soil before planting. Cover the seeds with a thin layer of soil or compost.
After planting, cover the soil with a cloche or SUNPRO Reusable Plant Blanket. This helps to keep the seeds warm. It also protects them from any unexpected frosts. Maintaining a steady temperature around the seeds improves germination rates.
Vining varieties typically grow in rows. Sow the seeds 4 to 6 inches apart in rows spaced 3 to 5 ft apart.
If you are also installing supports for the cukes, this is the ideal time.
Bush types typically grow in mounds. The easiest way to learn how to plant these types is to create small mounds of soil roughly 1 ft wide and a few inches high.
Space the mounds 1 to 2 ft apart. Sow 2 to 3 seeds per mound. These can be thinned out after germination.
If you are learning how to plant cucumber seeds undercover, fill pots with a well-draining seed starter potting mix.
Make a hole 1 inch deep in the center of the pot. Sow one seed per pot, placing the seed on its edge.
Positioning the seed on its edge reduces the risk of the seed rotting before it germinates.
Cover the seed with compost and water. Place the pots on a warm, sunny windowsill to germinate.
Seeds started in pots can also be placed in an EarlyGrow Propagator to encourage germination. Aim to keep the temperatures around 86 ℉. Seeds started in temperatures below 50 ℉ are unlikely to germinate.
Post Germination Care
An important part of learning how to plant cucumber seeds is being able to care for the seedlings after they germinate.
Depending on the variety and temperatures germination typically takes 3 to 12 days.
Following germination, continue to care for the growing cukes.
Once the seedlings are 4 to 5 inches tall they can be thinned out. Use pruners to cut the seedlings down as close to the soil as possible. Do not pull the unwanted seedlings up. This can disturb the roots of the seedlings that you want to keep, causing them to fail.
For bush cukes growing in mounds, remove all but the strongest seedling.
Cukes growing in rows can be thinned to 1 to 1.5 ft apart.
If your seedlings are growing in their final planting position mulch the soil around the cukes. A layer of mulch helps the soil to retain moisture, reducing the risk of the soil drying out and the seedlings failing.
Gently water the soil when it shows signs of drying out.
How to Transplant Pot Growing Seedlings
Learning how to transplant growing seedlings is the most difficult aspect of caring for cukes.
Allow your seedlings to continue growing in their pots until the soil is warm enough to transplant. This is usually in early summer. If you are growing undercover you may be able to transplant the seedlings slightly earlier.
Hardening off the seedlings, gradually exposing them to their intended growing position helps the cukes to get used to their final growing conditions. This process also helps them to settle more quickly.
Before planting, prepare the soil by digging in lots of compost or well-rotted manure. You can also scatter a granular, general purpose fertilizer such as Down to Earth Vegetable Fertilizer over the soil and rake it in.
Transplant into a well-draining soil.
When you are ready to transplant, make a hole in the soil large enough to hold the pot. When placed in the hole the rim of your pot should sit level with the soil level. Place the pot in the hole and cover with some fresh compost or potting soil. As the roots grow the pot breaks down enabling the roots to spread and flourish.
If you aren’t using a biodegradable pot, carefully remove the plant from its pot. Handle the seedlings lights. Aim to disturb the root system as little as possible. You may find it easier to cut the pot away from the cuke.
Once removed from its pot, plant the seedling in the hole. The top of the root system should sit slightly below the level of the soil.
Water your young cukes well.
If you are growing more than one plant, space your cukes 2 to 3 ft apart.
How to Care for Growing Cucumbers
The following care tips can help you to cultivate strong, healthy and productive cukes. For more detailed care information, check out our Ultimate Guide to Growing Cucumbers in Pots.
Knowing how to correctly care for your cukes encourages lots of fruit to form.
Once planted into their final growing position, water your cukes regularly. Aim to keep the soil evenly moist. Do not water the plants so much that the soil becomes waterlogged. A soil moisture sensor can help you to get the balance right.
Water only the soil. Try to keep the foliage as dry as possible. This helps to reduce the risk of fungal diseases developing.
Start to apply a fortnightly dose of liquid fertilizer as soon as flowers appear. A balanced fertilizer is fine.
As the cukes grow, train them to climb the installed supports or trellising. This elevates the vines, freeing up more soil for planting. It also helps to prevent the fruit from contacting damp soil, which can lead to rot.
Pinch out growing tips on outdoor cukes once the main stem has produced 7 to 10 leaves. Pinching out is the process of removing the new leaves that form at the top of the growing shoot. Side shoots can be pinched out once they reach 2 ft or have produced around 8 leaves.
Greenhouse or Indoor Care
Cukes suited for growing undercover require a little more attention than those growing in garden beds.
If you are growing in a greenhouse, you can plant in beds, large pots filled with potting soil or grow bags. Tall Gallon Grow Pots are made from a durable material that is also breathable. This helps to aerate the soil, preventing issues commonly caused by overwatering.
Cukes growing undercover require a little more care than those outside.
Try not to overplant your grow bags, the roots and vines need room to spread. Do not plant more than 2 or 3 cukes per bag.
Many people like to plant their cucumbers in bottomless pots set on the top of the grow bag or bed. Here the bottomless pot helps to trap the moisture around the root system when watering.
Unless you water very precisely with a watering can, water can pour down the sides of the grow bag instead of sinking into the soil. This is not only a waste of water, it also doesn’t help to hydrate your cukes. Using a bottomless pot helps to prove the efficiency of your watering routine.
Remember to install vine supports when planting. Bamboo canes or a Vegetable trellis can be used, depending on your growing set up. As the cukes grow, train the vines to climb up the supports.
Pinch out the growing tips when the vines reach the top of the support or the roof of the greenhouse. At this stage the plant should be leafy and healthy. Pinching out encourages side shoots to develop.
Fertilize your cukes every two weeks with a potassium rich fertilizer. Dr. Earth Organic Tomato, Vegetable & Herb Fertilizer can also be used.
Cukes growing undercover require more regular watering than those growing outside. Remember these are thirsty specimens that struggle if the soil is allowed to dry out.
If you are growing a variety that produces both make and female flowers, remove the male blooms from the vine. This helps to prevent bitter-tasting fruit from developing.
Female flowers can be identified by the slight swelling which develops behind the bloom. This swelling is the developing fruit. Male flowers do not produce fruit.
The slight swelling behind the bloom of a female flower.
You can also plant all-female cucumber seeds. These wont produce male flowers.
How to Pollinate
Self-pollinating plants, cucumbers can produce both male and female flowers.
Most indoor types produce only female flowers. These are able to produce fruit without the need for pollination. In some cases the presence of male flowers can make the fruit taste bitter. Cut away any male flowers as they form.
Most varieties are self pollinating.
Outdoor cucumbers produce both make and female flowers. Here pollination is necessary for fruit to form. In most cases pollinators such as bees pollinate the flowers. Planting pollinators friendly flowers such as marigolds close to your cukes helps to increase pollination rates.
How and When to Harvest
After learning how to plant cucumber seeds and caring correctly for the growing cukes, the next step on your journey is learning how to harvest.
The best time to harvest a cucumber is when it is small and tender. Most cucumbers achieve a mature size of 3 to 8 inches however different varieties can produce fruit of different sizes. Check your seed packet for the mature size of your fruit.
Do not let the fruit sit on the vine for too long. This can cause the flavor and quality to deteriorate. Additionally, if you allow one fruit to sit on the vine for so long that it sets seed the entire plant can stop fruiting.
Use a sharp knife or scissors to cut the ripe fruit from the vine. Pulling the fruit risks damaging both the fruit and the vine. It can also cause other, developing fruit to fall from the cuke. Harvesting regularly encourages more fruit to form.
Cut the fruit from the vine.
The best time to harvest the fruit is in the morning while it is still cool and the fruits are juicy,
How to Identify and Treat Common Problems
Once you know how to plant cucumber seeds and care for the plant, the next step is being able to spot any problems that are developing. Luckily, with the right care, issues such as powdery mildew are unlikely to appear.
Make sure your cukes have lots of room to grow into.
Powdery mildew is the most common issue to affect growing cukes. This is a fungal disease which can cause a powdery white substance to form on the leaves before they shrivel up.
There are a number of ways to prevent powdery mildew from forming. Spacing out the cukes so that air can circulate between them and watering only the soil, keeping the foliage as dry as possible, are two easy to adopt preventative measures.
Cukes that are underwatered or drought-stressed are more prone to developing powdery mildew. Should this issue develop, our guide to powdery mildew treatment explains how to treat the disease.
One of the most common plant diseases, mosaic virus causes leaves to yellow and develop a characteristic mosaic pattern. Affected cukes are unlikely to produce flowers. Should fruit develop they will be small and inedible.
Lift and destroy any affected cukes. Sterilize your tools before and after use to prevent accidentally spreading the diseases to other parts of the garden. If mosaic virus is a persistent problem in your area, disease resistant varieties such as Straight Eight and Tasty Jade are available.
Cuke’s wilting is usually a sign of underwatering. It can also be triggered if the cukes are exposed to sudden changes in temperature or draughts. When growing undercover try to keep the temperature around the cukes as constant as possible.
Greenhouse spider mite is a sap-sucking mite that affects cukes growing in greenhouses. Spider mites cover the leaves and stems of the cuke in a fine webbing. Severe infestations can cause cukes to fail.
Greenhouse spider mite is unlikely to develop in well ventilated areas. Using a Casa Basic Plant Mister Bottle to spray the foliage with water raises humidity levels and deters spider mites. Another way to raise humidity levels is to use a garden hose to damp down the greenhouse floor.
Glasshouse whitefly is a sap sucking pests that covers affected specimens in honeydew. Affected foliage can be treated with an application of soapy water or insecticidal soap.
Check the cukes regularly for signs of infestation.
Cucumber beetles can also be problematic. Their presence can slow or deter healthy growth. Planting Tansies close to your cukes is an effective way to deter the pests.
If you are learning how to plant cucumber seeds outside, adopting a system of crop rotation helps to keep your soil healthy and cukes productive. Grow your cukes in soil that held legumes or spinach the previous year. Your cukes can be followed by a winter planting of a nitrogen-fixing ground cover plant such as clover.
Learning how to plant cucumber seeds is a useful and easy skill to master. Not only does it enable you to grow a wider variety of cukes, it is also a transferable skill. Once you know how to plant cucumber seeds you can sow a whole range of other vegetable and flower seeds.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.