The amateur grower, mainly for economic reasons and quantity required, will generally grow their cucumbers in either a cool greenhouse, coldframe or in the open on soil ridges.

Whereas the commercial growers may grow their crops hydroponically, and in an environment where they can maintain temperature of 21°C (70°F).

For this reason the writer has only considered the amateur approach to growing cucumber under glass.

Cucumbers are half hardy, and varieties are normally classified by the type of culture they are best suited.

They can grow to over 3metres (10ft) high, but are generally confined to the height of the greenhouse they are being grown in, unless they are being grown in an espalier fashion along wires strung along the greenhouse.

Depending upon variety, the fruit can grow up to 500mm (18") long and 60mm (2.5") in diameter and are ready for harvesting around the end of July.

Quite often the grower will grow their cucumber alongside their tomatoes, when ideally the humidity for cucumber growing should be higher than that provided for tomatoes.

However, by siting the cucumber growing area at the opposite end of the greenhouse from the door the potential is there for conditions to be slightly more humid.


Week 17:

Sow seed on their side singly into cell trays, or 75mm (3") pots of seed compost.

Germinate at 18°-21°C (65°-70°F)

Germination may take four or five days.

Germinated seedlings

Week 18:

When the seedlings have three true leaves, pot them singly into 150mm (6") pots of potting compost, setting them so as the bottom set of leaves are just above soil level.

Place the seedlings where they can get maximum light (but not direct sunlight) maintain a minimum temperature of 16°C (60°F)

Week 20:

Prepare the growing bed by incorporating liberal amounts of well rotted manure or compost.

Rake in bone meal mixed with lime at a rate of 100gm per sq.m (4oz/sq. m)

Week 21:

Plant out in the greenhouse border 300-900mm (1-3ft) apart.

Insert a cane into the planting hole at this time to prevent the possibility of damaging the roots if done later.

Water the plants in to settle the soil around the root ball.

If the plants are quite tall or leggy tie them into the cane.

Planted Out
Growing On
Fruit Forming

Keep the compost thoroughly moist but never waterlogged – little and often is the rule.

Cucumber plants are susceptible to neck rot this is often caused by over wet soil at the point where the plant emerges from the soil.

There are a few ways to avoid this;

1) Mound some soil up around the base of the plant this will allow water to run away from the stem when watering, thus keeping this area relatively dry.

2) At planting time, sink a 100-125mm (4"-5") plant pot into the soil.

Filling this at watering times will again keep the surface area around the plant relatively dry.

3) At planting time place a sleeve around the base of the plant to prevent water coming in direct contact with the plant/s.

Keep the air as moist and well ventilated as the other plants in the house will allow.

Spray the floor (not the plants) to maintain a high humidity, or leave a bucket of water nearby.

Neck Rot protection in place

Week 24:

The plants will be growing quite rapidly at this time so will require constant tying in.

Depending upon the style of growing on i.e. if growing as a cordon (vertically) or on lateral growths in an espalier form (horizontal along wires) tie the plants in loosely every 200mm (8")

Pinch out the growing tip after the fifth/sixth pair of leaves this will encourage the formation of sideshoots.

Stop each lateral (fruit-bearing growths) at the second leaf joint.

Remove tendrils and pollen-bearing male flowers to prevent bitter tasting fruit as they appear.

Allow only two female flowers on each lateral, female flowers are distinguished from male flowers by the tiny immature cucumber behind the flower.

Male Flower
Female Flower

Water regularly, maintain a humid atmosphere around the plants, and keep well ventilated on hot days.

Week 26:

Feed fortnightly from now on, with a high nitrogen fertiliser.

Week 29:

Harvest cucumbers when they are young to get the optimum flavour, this will also encourage further cropping.

Cut, do not pull, when removing the fruit from the vine.

If fruit is left on plants too long, i.e. to the point where they turn yellow, they will go to seed and further cropping will stop.

Ready for Harvesting
Harvested Fruit

Potential problems

Powdery mildew is a disease that affects all cucurbits including cucumber.

It is caused by several species of related fungi that overwinter on dead plants and in spring they release their airborne spores which in turn infect the cucumber leaves.

Initially this appears as a white dusty coating on the leaves that eventually forms another type of spore that spreads the disease.

Plants that are stressed are generally more susceptible to the disease so ensure that the plant/s don't want for moisture and that the humidity around the plants is minimal.

When humidity is high condensates form on the leaves and acts as an adhesive for the spores to stick too, therefore it is wise to keep the plants well ventilated.

Control can be difficult!

Using Green or yellow sulphur may give some control, otherwise destroy affected plants (do not compost them)

Cucumber mosaic virus (CMV) and Zucchini yellow mosaic virus are quite common, and can affect other cucurbits.

The viruses are generally transmitted by aphids, although CMV may be transmitted through contaminated seed.

Symptoms appear as yellow mosaic patterns on the leaves, distortion and stunting.

The only cure is to destroy infected plants (do not compost them)

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