How to Grow Cucumbers

Cucumber seeds are a fantastic addition to Australian vegetable gardens. They’re relatively easy to grow and can produce surprisingly large yields compared to many vegetable seeds – plus, home-grown cucumbers taste so much better than shop-bought offerings. Their mild flavour and refreshing crunch are perfect for summer salads and sandwiches, and baby varieties make great snacks for kids! 

Learn everything there is to know about growing cucumbers here at Mr Fothergill’s. In this guide, we’ll walk you through how to grow cucumbers step-by-step, from soil preparation to harvest. With a little care and know-how, you’ll soon be enjoying delicious, freshly picked cucumbers all summer long.

Cucumber Classification

Family

Cucurbitaceae.

Genus

Cucumis sativus.

Cucumber Seed Varieties

Cucumbers come in a diverse range of shapes and sizes, with varieties perfectly suited to different culinary uses and growing conditions. At Mr Fothergill's, we offer a wide selection of cucumber seeds that grow well in Australia, including: 

• Lebanese
• Spacemaster
• Pickling Gherkin
• RHS Emilie F1
• Richmond Green Apple
• Telegraph Improved

There are so many to choose from; seedless cultivars, ‘burpless’ cucumbers, baby varieties (great for snacking), and others that are prized for their superior flavour or bumper harvests. 

Cucumbers thrive in sunny, well-prepared garden beds with nutrient-rich, well-draining soil. The perfect soil for sowing cucumbers has a slightly acidic to neutral pH (6.0-7.0).

Begin by thoroughly weeding the area and working the soil. Then, mix in plenty of organic matter, such as well-rotted compost or aged manure. This will add vital nutrients to boost soil fertility as well as improve aeration and drainage - a particularly important step with heavy clay-based soils. 

You can also grow cucumbers in raised beds or pots with drainage holes. There are many great compact bush-type cultivars that make excellent container garden seeds.

When to Sow Cucumber Seeds

For most areas of Australia, cucumber seeds should be sown from spring through early summer. Cucumbers can be damaged by the cold, so wait until the soil has warmed and the threat of frost has passed. 

In temperate regions, the best time to sow cucumber seeds is September to January. In warm regions with mild winters, the window is much longer – you can sow cucumber seeds from July right through to March. If you live in a cooler part of the country, such as Tasmania, you may need to wait until October before sowing. 

How to Sow Cucumber Seeds

Provided the soil is warm enough (15°C-21°C, depending on the cultivar), you can sow cucumber seeds outdoors directly in their final growing position. 

Sow clumps of 2-5 seeds 12mm deep in mounds of moist compost or soil and firm down gently. Space the clumps 30-60cm apart to give plants room to grow, allowing 100-120cm of space between rows. Keep the soil well-watered until your cucumber seeds germinate. You should see seedlings emerge in 6-10 days, at which point you can thin out the clumps to the strongest 1-2 seedlings.

Alternatively, you can germinate your cucumber seeds indoors using seed raising equipment, such as seed trays and a heat pad, and move plants outside once the weather warms.

Where to Plant Cucumber Seeds

Your cucumbers will need a lot of sunlight. Select a warm, bright location that receives full sun for at least six hours each day, but is sheltered from strong winds. 

If you live somewhere with very hot summers, it may be beneficial to provide some shade to protect your plants from the harsh sun. Cucumber seeds should still grow well in slight shade if the air is warm.

Vine-type cucumber varieties will do best if allowed to climb, so planting at the base of a fence, trellis or netting is ideal. This may not be necessary with compact and bushy plants that don’t require support.

How to Grow Cucumber Seeds

Cucumber seeds, like zucchini seeds, need a lot of nutrition to keep them healthy and productive. As seedlings grow, keep the soil well-mulched and regularly remove weeds. Apply a balanced liquid feed every 1-6 weeks according to the growing instructions. Water your cucumber plants frequently at the roots, keeping the leaves dry. 

Once your plants are tall and strong enough, tie the stems to a support (if using). As they continue to grow, their vines will naturally grasp the support themselves. For most varieties of cucumber, it’s recommended to pinch out the growing tip when 5-6 leaves appear to encourage side shoots and bigger crops.

Pruning Cucumber Plants

It’s not always necessary to prune cucumber plants; in fact, letting side shoots grow often means a bigger harvest. However, you can trim any side shoots that do not grow flowers, as these won’t produce cucumbers. Pruning them will help the plant focus its energy on growing fruit.

You may also wish to prune trellised cucumbers if you are short on horizontal space. Removing side shoots will encourage vertical growth, making harvesting easier.

Finally, if vine-type cucumber plants grow too many leaves, this can restrict airflow and increase the risk of mildew. Remove older leaves periodically to reduce bushiness and help air circulate. 

 Removing Male Flowers

Some modern hybrid cucumbers are parthenocarpic: they produce fruit without the need for pollination. These varieties will only grow female flowers, and the fruit is usually seedless. This allows for increased yields and a plant that isn't dependent on pollination. These fruits can be grown in a polytunnel or undercover for a longer harvest period. 

However, if the plant is stressed, it may occasionally produce a male flower that has no swelling behind the petals. Remove any male flowers as soon as possible, as pollinated female flowers tend to produce bitter fruits.

Note that this advice does not apply to non-parthenocarpic cucumbers. These must be pollinated (by insects or by hand) in order to produce fruit – so removing the male flowers will mean no cucumbers grow at all.

Pest and Disease Advice

There are a number of pests and diseases that can affect cucumber plants. Here are some of the most common culprits and how to deal with them.

Pests

Some Australian pests that cucumbers are susceptible to include aphids and leaf-eating ladybirds, also called 28 spotted ladybirds. 

While leaf-eating ladybirds can be picked off by hand, aphids are too small. If you notice very small green, yellow, brown or black bugs on your cucumbers, you can remove them with a quick spray of the garden hose or some soapy water. 

Cucumber plants may also be targeted by slugs and snails, especially when young. You can protect your plants with a physical barrier, such as eggshells, or apply organic slug pellets.

Diseases

Cucumbers are prone to powdery mildew and downy mildew: fungal diseases that produce white, brown or yellow patches on leaves. If left unchecked, they can stunt your cucumbers’ growth or even kill the plant. 

These fungi like dampness and humidity, so always water your plants at the roots and trim old leaves to help air circulate. If you notice signs of mildew, remove any affected leaves, and apply a fungicide if the problem persists.

You should also watch out for cucumber mosaic virus, which causes yellowing and mosaic-like patterning on leaves, and prevents flowers and cucumbers from growing. There is no cure for cucumber mosaic virus, so destroy any affected plants immediately to stop it spreading to other plants.

Companion Plants

There are many excellent companion planting seeds for cucumbers. Corn seeds are a particularly popular choice for vine cucumbers, as the stalks can be used as natural supports. Other good companion plants for cucumbers include:

• Legumes, such as pea seeds and bean seeds: these help improve nitrogen levels in the soil.
• Nasturtium and marigold seeds, which act as natural pest repellents.
• Root vegetables, like radish seeds and parsnip seeds: as these grow mostly beneath the soil, they won’t compete for space with cucumber plants and can help improve soil drainage and aeration. 

For more information and recommendations on the best companion plants for cucumber, see our detailed companion planting guide.

Most cucumber varieties will be ready to harvest from 7-12 weeks after planting. Cucumbers should be picked while young and tender – if allowed to grow too large, they may end up bitter or tough. You can judge this by the size of the fruit:

• Gherkins and baby cucumbers: harvest when 5-10cm long
• Salad cucumbers: harvest when 10-20cm long
• Slicing cucumbers and longer varieties: harvest when 15-30cm long

Picking cucumbers regularly will help stimulate the plant to grow more fruit, so you can enjoy continued harvests throughout the growing season.

How to Harvest Cucumber Seeds

If you want to harvest cucumber seeds to plant next year, wait for the cucumber to fully mature on the plant. Then, scoop out the seeds and soak them in water for a few days before spreading them out to dry. Store the dried seeds in an airtight container in a cool, dry place until ready for sowing.

However, bear in mind that parthenocarpic cucumbers are typically seedless, and seeds from hybrid cucumbers will not produce a true copy of the parent. Additionally, outdoor cucumbers may cross-pollinate with other cucurbits – meaning their seeds may produce plants crossed with squashes or zucchinis.