Fruit vegetables
Cucumber
Cucumis sativus
Timings for your region
Suggested: Moderate · Explained in the glossary
Start indoorsearly April – early May
Sow outdoorsmid May – mid June
Plantingmid May – early June
Harvestearly July – late September
Practical tip
Cucumbers hate cold water and cold soil — better to plant a week late than into ground that is still cold.
Origin & history
The cucumber comes from the southern Himalayan region, where it has been grown for over 3,000 years; the Romans carried it across the Alps, and it already appears in Charlemagne’s estate ordinance of around 800. In Germany it became an everyday vegetable mainly through pickling — Spreewald gherkins have carried a protected geographical indication since 1999. Botanically, incidentally, the cucumber fruit is a berry.
Varieties
Slicing cucumbers give you a few large fruits, pickling types many small ones — for a jar of gherkins you want the latter. Outdoors the choice of variety matters more than anything else: take types explicitly sold for open ground, as pure greenhouse varieties often stay stunted in a bed. Modern F1 varieties flower almost entirely female and therefore crop far more heavily; grafted young plants, usually on fig-leaf gourd, cope with cool soil better than plants on their own roots.
Care
Cucumbers are shallow-rooted — do not hoe between the plants, mulch instead, which keeps the soil evenly moist and warm. Water generously and at the base, in the main season preferring two thorough soakings a week to a daily sip, and feed regularly from the first fruit set. Trained up a net or frame they take less space, the fruit stays clean and the foliage dries faster after rain. On classic outdoor varieties pinch out the tip after the fifth or sixth leaf so side shoots form — that is where the female flowers sit.
What can go wrong
Powdery mildew coats the leaves with a white, floury film from midsummer; downy mildew shows as angular yellow patches bounded by the leaf veins. You slow both down with generous spacing, training upward, watering at the base rather than over the foliage, and removing the first affected leaves early — and there are varieties sold with stated tolerance. Bitter fruit has become rare in the modern bitter-free varieties and otherwise turns up mainly after cold stress or uneven watering; a cucumber that tastes bitter does not belong on the plate.
Harvest, storage & kitchen
Pick gherkins at 8 to 10 cm and every two or three days — the more often you cut, the more the plant sets. Slicing cucumbers are ready when they are evenly thick and still dark green; fruit that has turned yellow is overripe and tastes of seeds. Do not put them in a cold fridge: below about 10 °C the skin develops glassy patches. And not next to apples or tomatoes either — the ripening gas they give off yellows cucumbers within days.
All timings are guide values for the given climate, not a guarantee. Weather, aspect and variety all have a say.