Family: Cucurbitaceae

Countries: Africa, Angola, Asia, Botswana, Eswatini, India, Malawi, Mozambique, Tanzania, Zaire, Zambia, Zimbabwe

Cucumbers (also known by their botanical name – Cucumis sativus) are popular vegetables that are easy to grow and can produce a bountiful harvested of cucumbers.  Cucumber plants form climbing or trailing plants that can be left to scramble horizontally over the ground or trained to grow vertically using wires, twines, or other supports.

Gardeners can choose from a range of cucumber varieties available at nurseries, garden centres, and online retailers.  There are many cucumber varieties each of these varieties will be one of two types of cucumbers – they will either be ‘indoor cucumbers’ or ‘outdoor cucumbers’.  ‘Indoor cucumbers’ have smooth skins (without any spines) and can be grown inside glasshouses or polytunnels, or outdoors in warm summers and southern areas.  In cooler summers or northerly districts, ‘indoor cucumbers’ need to be grown inside a greenhouse or polytunnel.  ‘Indoor cucumbers’ are self-fertile and don’t want to be pollinated.  If an ‘indoor cucumber’ plant produces a male flower (or a plant nearby produces a male flower) and the plants are pollinated their cucumbers will taste bitter.  To avoid any risk of bitter cucumbers, grow all-female F1 hybrid plants (like Cucumber ‘Party Time’) and don’t grow ‘indoor cucumbers’ together with ‘outdoor cucumbers’.  This is important as ‘outdoor cucumbers’ differ – ‘outdoor cucumbers’ readily produce male flowers and these types of cucumbers must be pollinated to produce a harvest.  As you might expect, ‘outdoor cucumber’ varieties are ideally suited for outdoor cultivation.  It varies depending on the variety and the plants’ growing conditions, but ‘outdoor cucumbers’ have rougher skins with a slightly ridged or uneven texture and are covered to varying degrees with small spines (the spines are minor and are easily rubbed off).  All cucumbers (both indoor and outdoor types) are tender plants that must be grown in a warm, frost-free environment.  When you’re purchasing cucumber seeds or buying cucumber plants, check the seed packet or label to find the cucumber variety that’s best suited to your needs.

Sow cucumber seeds from March to June in a protected or frost free environment – ideally inside a glasshouse, polytunnel, conservatory, or porch or outdoors when all risk of frost has passed.  Both ‘outdoor’ and ‘indoor’ cucumber seeds can be sown from March to June indoors, or from May to the end of June, outside in frost-free areas.  The further North you are the earlier you need to sow your cucumber seeds – finish sowing seed by the beginning of June in colder areas.  Cucumber seeds can also be started off on a bright and sunny window sill, but if a window sill is your only space available for growing cucumbers, wait until the beginning of May to sow seeds, as these plants need bright indirect sunlight from above and optimum growing conditions to thrive.  Cucumber plants will be happiest with a shorter period of indoor cultivation, but starting seed off indoors saves time and enables cucumber plants to be productive earlier in the season.  Other options are to grow or start off cucumbers in a cold frame, or use cloches to protect May-sown seedlings.

If you’re growing cucumbers in containers, don’t be tempted to use too small a seed tray or planter.  Cucumbers have large seeds that are best started in pots or sown directly in a greenhouse border.  Use peat-free compost to grow cucumbers.  Some growers like to sow cucumber seeds vertically to prevent the seeds rotting, but if you’re raising your seeds in an area with optimum temperatures of around 21C (70F), rotting shouldn’t be a problem – this is something that is more likely to happen if you’re attempting to grow cucumbers in too cool temperatures, as in lower temperatures the seed takes longer to germinate (or doesn’t germinate), when the seed is more likely to rot.

This year, mice have taken quite a shine to my cucumber seeds; they broke my heart (and budget for seeds) by taking 80 of my cucumber seeds that had just germinated.  I’ve found that mice don’t like the scent of peppermint; I like to capitalise on this and I often dot mint oil around my seedlings in my mini glasshouse.  I have lots of mint plants growing in planters that I could mingle in and around my seedlings, if I had a larger growing space, but I don’t have enough room for all the seeds I want to sow – so I use mint oil instead, as it has a concentrated aroma and the effect lasts a long time, away from rain undercover in my mini glasshouse.  Slugs and snails may devour cucumber seedlings; avoid problems with mollusks by using the trialled and tested and proven deterrents from my Slug and Snail Trial.

Cucumbers are tender plants that are killed by frosts and need temperatures above a minimum of 13C (55F) at night.  Please don’t be tempted to sow your cucumber seeds too early outdoors or rush to move your plants outside while there is still a danger of frost.  Harden your plants off before planting them outdoors.  To harden plants off: move your cucumber plants outside in the morning and bring the plants indoors at night, every night for at least two weeks prior to planting.

Outdoors, plant cucumbers in a bright and sunny, yet sheltered position.  Avoid growing cucumbers on exposed, windy sites, as they will not flourish in these conditions.  Cucumbers thrive in evenly moist soil or peat-free compost.  Avoid growing cucumbers in wet or water-logged soils.

When watering cucumber plants, try to avoid wetting the main stem or leaves and don’t pour water onto the crown of the plant, as this can cause problems.  Instead, water the compost around the outer circumference of the cucumber plant’s pot, keeping the stem and leaves dry whenever possible.

For greenhouse grown cucumber plants: use blinds, or coverings (like a net curtain, an old sheet, or shade paint) to diffuse and soften the intensity of sunlight that reaches your cucumber plants’s foliage.  Glasshouse grown plants are at risk of scorch which can cause serious damage to cucumber plants’ leaves.  It is especially important to protect your glasshouse grown cucumber plants’ from the middle of spring until early autumn, as sunlight tends to be more intense during the main growing season, but scorch can occur earlier or later if we experience brighter sunshine than usual earlier in the season.  Damping down the glasshouse floor will help to raise the humidity levels and improve growing conditions for your cucumber plants.

Cucumbers can be grown in peat-free compost in containers, or grown directly in the soil.  If you’re growing cucumbers in containers, don’t use too small a planter.

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