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How To Grow Cucumbers

How to Grow Cucumbers: Care Tips

The cool, crisp taste of cucumbers is even better when you grow your own! Our step by step guide to growing cucumbers will show you all need to know.

Most common Cucumber plant questions

When can I plant Cucumbers?

You can plant cucumber plants in a greenhouse from April, and even March if it is heated.

When you plant cucumbers depends on what variety of cucumbers you have and whether or not you have a greenhouse. Check the product description of your cucumber plant to see exactly when you can plant your cucumber plant and where. If you are planting cucumbers outside, then you should plant them from May if it is hot or even wait until June.

Cucumbers prefer temperatures that are consistently around 20℃ and therefore will not do well outside before mid-summer. They also prefer a decent level of humidity which is why people pretend to prefer growing them in greenhouses as this can be more easily controlled. Different varieties, however, are more hardy to the British climate and do well grown outside.

How much sun do Cucumbers need?

Cucumber plants need a spot with full sun.

Position them where they will receive 8-6 hours of sunlight a day.

Where should I position my Cucumber plants?

Position cucumber plants somewhere sheltered.

Make sure that they are protected from cold winds chilling the plants.

How much water do Cucumber plants need?

Cucumber plants need to be regularly watered.

Feel the soil and if it is dry to the touch a fingernail deep, then give the plant a watering. On hot, summer days, this means watering once a day.

If the soil becomes too dry too regularly this will stunt the growth of cucumbers and cause them to taste bitter.

How to feed Cucumber plants

After the first flowers appear, start feeding the cucumber plant every week.

Use a fertiliser high in potash, such as organic chicken manure pellets or liquid tomato feed.

Potash, or potassium, is one of the three main elements in fertilisers along with nitrogen and phosphorus. Potash stimulates growth in the fruits and vegetables and so typically gardeners apply it as the plant begins to develop them.

What kind of soil do Cucumber plants need?

Cucumber plants prefer fertile, well-draining soil.

To achieve this you can create a mix of one part garden topsoil and 3 parts quality compost. If possible you should add a layer of well-rotted manure to your soil the previous Autumn and allow it to rot down. This will give your soil extra slow-releasing nutrients and also improve the texture of the soil so that it drains water better.

Growing Cucumbers in pots

Plant your cucumber plant in a 9cm pot, filling it with quality compost and then digging a small hole big enough to fit the roots in.

Place the roots of the plants into the hole and then fill in with soil and gently firm down with the tips of your fingers. Give it a watering so that the soil settles around the roots.

When the plant has reached 15-20cm tall you can then move it to its larger, permanent pot. For this you will want a pot which is 30cm across, which is usually 15L. Fill the larger pot with quality of compost and then dig a hole large enough for the plant’s current pot to fit in plus another couple of inches.

Then, turn the plant in the 9cm pot upside down holding the plant in and gently tease the plant and the root ball from the pot by squeezing the pot and pulling it out. Place the plant and root ball in the hole and fill in with more soil. Give the plant a watering to settle the soil around the roots.

When the weather is consistently warm around late May to June, you can then move the plants outside. If you are planting the cucumber plant in a pot then see above for instructions, if you are planting them in the ground, then see below.

Growing Cucumbers outside

If your plant has arrived before May-June, then plant it in a 9cm pot using the above method with quality compost and leave on the window sill in a sunny, warm spot.

If you are growing cucumber plants vertically up a support then they can be planted 45cm apart. If you are leaving them to sprawl along the ground then they must be planted 1m apart.

If you are planting cucumber plants in the ground then dig a hole that is big enough for its current pot to fit in plus another couple of inches in every direction. Then, turn the plant in the 9cm pot upside down holding the plant in and gently tease the plant and the root ball from the pot by squeezing the pot and pulling it out. Place the plant and root ball in the hole and fill in with more soil. Give the plant a watering to settle the soil around the roots.

Do Cucumber plants need support?

Cucumbers are vine plants and so often cannot support their own weight, especially as they grow large fruit.

If you do grow cucumbers with no support then they will sprawl along the floor and therefore need more room between each plant–at least 1m.

You can train a cucumber up a support such as a vertical wire, stake or a trellis. To do this, plant your cucumber plant about 3cm from the base of the support.

If you are training the plant up a stake or trellis then tie the stem in about every 20cm using a material such as string or nylon.

If you are training your plant up a vertical wire then simply wrap the stem gently around the wire every couple of days as it grows.

When tying a plant in with string, tie several loops around the plant first and then tie to the support to prevent the plant rubbing against the support which will cause damage.

How to care for Cucumber plants

Cucumbers will benefit from a mulch which will help trap moisture and provide nutrients to the plant.

A mulch such as dried leaves, straw, or even a layer of compost would be good to use for cucumbers.

How to prune Cucumber plants

Depending on the variety of cucumber plant you have, you may need to remove the male flowers.

If, in the product description, it says the plant is fully female and self-pollinating, then you should remove the male flowers. You can identify male flowers because they are growing at the end of a plain stalk whereas the female flowers are growing from what looks like small cucumbers.

If you are growing cucumbers vertically, once the plant has grown to the top of their support, then prune back the main stem.

If a side shoot has produced two leaves after a cucumber, then you can prune away any further growth from this stem. This will encourage more side shoots to grow and more cucumbers.

The reason why male flowers are pruned away is because when insects pollinate the flowers this can cause the cucumbers to become bitter and taste less good. Some varieties of cucumber plants have no male flowers, they are female only. Check the product description to see if this is the case. If it is then you do not need to prune away any of the flowers.

How to harvest Cucumbers

Cucumber plants generally take 2-3 months to harvest after you’ve planted them.

They will be ready to harvest from July through to October. You can simply cut them off with a sharp, sterilised knife or scissors once it is as big as you like it.

The sooner you harvest the cucumber the sooner the plant will grow a new one so be sure to harvest regularly for lots of fresh cucumbers.

Common Cucumber plant problems

The most common cucumber pests and diseases are Whitefly, Cucumber Mosaic Virus, Aphids, Powdery Mildew and Squash Anthracnose.

The best protection against these scourges is to try and prevent too much humidity on the leaves by watering in the morning and preventing splashing from the soil to the leaves. Also planting companion plants such as Marigolds will attract predators such as ladybirds and hoverflies which will eat the pests. See below for a description of each problem.

What is Cucumber Mosiac Virus?

Cucumber Mosaic Virus appears as yellow blotching on the leaves and can cause the fruit to become deformed and blistered.

CMS cannot spread itself and is so spread by vectors such as contaminated hands and tools, pollen, and commonly aphids.

To prevent CMS you have to try and prevent contamination. Always maintain good garden hygiene by cleaning tools and boots if visiting another garden.

If your plant is infected with CMS, remove and bin the infected plants. Clean all tools thoroughly after doing this.

Whitefly

Whiteflies look like small white moths and are most commonly found on the underside of leaves. If left unchecked they will feed on the leaves and turn them yellow.

Your best, natural defence against whitefly is to simply spray your plant down with some water, aiming it at the whiteflies to try and wash them off. Make sure you check the whole plant and get as much off as possible. If the problem persists you can buy a special bug spray that specifically targets these pests and is safe to spray on your cucumbers.

You can also plant companion plants such as Marigold near your cucumbers. Marigolds deter whiteflies as well as attracting ladybirds and hoverflies which will come and actually eat the whiteflies.

Aphids

Aphids are small green bugs that cluster on the stems, particularly at the joints, and also the underside of leaves. They cause leaves and fruit to discolour and misshapen. Aphids also leave behind a sticky residue known as honeydew which can then promote the growth of a fungus known as sooty mould.

Like Whiteflies, ladybirds and hoverflies enjoy eating aphids so planting Marigolds nearby will help control the pest. Also, the same chemical sprays that work for Whitefly tends to also work against aphids. You can also use soapy water to try and wash the aphids off of the plant.

Powdery Mildew

Powdery Mildew is a fungal disease that usually attacks the leaves and stems of a plant, leaving a white powdery residue.

It can cause stunted growth and affect crop yields.

Powdery mildew thrives in hot humid conditions. To prevent it from affecting your plant try to keep the ground free of weeds. Also always water at the base of the plant in the morning so the day has enough time to evaporate away the surface water and try to prevent splashing from the ground to the leaves.

If your plant is suffering from powdery mildew then promptly prune away infected leaves at the stem with a sharp, sterilised tool. If you cut one leaf away be sure to sterilise the tool before touching another part of the plant or other plants in your garden as this can cause the infection to spread. You can then spray the plant down with a mix of one teaspoon of baking soda mixed with a litre of water.

Squash Anthracnose

Squash Anthracnose is a fungal disease that causes brown spots to appear on the leaves which can also become yellow and wilted.

This can cause leaves to eventually fall of stunting growth and also directly producing dark, sunken rot in the cucumbers themselves.

Squash Anthracnose is caused by wet weather and to best prevent it you should try and ensure there is good air circulation around the plant, such as by training it vertically with enough space in between plants. You should also water it in the morning so the day has enough time to evaporate away the surface water and try to prevent splashing from the ground to the leaves.

If your plant is suffering from Anthracnose then promptly prune away infected leaves at the stem with a sharp, sterilised tool. If you cut one leaf away be sure to sterilise the tool before touching another part of the plant or other plants in your garden as this can cause the infection to spread. Burn the leaves or bin them, do not put them into the compost.

To try and control Anthracnose you can try and spray your plant with a copper-based fungicide. Read the directions and be careful because too much copper in the soil can kill beneficial microbes. If more than ⅓ of the plant is infected you may have to tear the plant out and bin it.

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