🌱✗ Tested and false“Cucumber flowers always need pollinating to set fruit, so leave every flower alone”
Greenhouse varieties are almost all-female F1 hybrids: any male flowers that do appear must be removed, since pollination makes the fruit bitter and full of seed. Outdoor/ridge varieties are the opposite, producing both male and female flowers that genuinely need insect pollination, and cloche or frame covers must be opened in the day so pollinators can reach them.
Our read Tomatoes and most other greenhouse crops are helped along by pollination, so it's a reasonable-looking default to assume the same for cucumbers. This is one crop where the opposite instinct, at least for one of its two types, is correct.
What to do: Check which type you're growing before you touch a flower. Remove any male flowers on a greenhouse/all-female variety. Leave every flower alone on an outdoor variety, and make sure pollinators can actually reach them if it's under a cloche.
2 sources
- RHSGreenhouse cucumbers... produce almost exclusively female flowers... these must not be pollinated, otherwise the resulting fruits will be bitter. Outdoor cucumbers produce both male and female flowers; don't remove the male flowers as pollination by insects is necessary for fruit to develop
- TeagascOutdoors, female flowers are naturally pollinated by insects... if plants are grown under cloches or frames, these must be opened during the day to allow insects access to the flowers
“Cucumber spacing is the same whether you're growing indoors or outdoors”
Spacing changes with growing method: 60cm for a greenhouse plant trained up a support, 45cm for a trained outdoor plant, and 90cm for an outdoor plant left to sprawl. Outdoor ridge cucumbers can also be spaced by area instead, about 2.5 square metres per plant, reflecting how much more ground a sprawling plant actually uses.
Our read A single spacing figure works for most vegetables regardless of exactly how they're supported, so it's easy to assume the same here. Cucumbers vary this much specifically because a trained, vertical plant and a sprawling one are using the growing space in genuinely different ways.
What to do: Match your spacing to your method: tight and vertical under cover, wider if trained outdoors, and wider still, or by area rather than by a single distance, if you're letting outdoor plants sprawl.
2 sources
- Gardener's World60cm apart (greenhouse); 45cm (outdoor trained); 90cm (outdoor sprawling)
- TeagascSpace required per plant will be about 2.5 square metres
“Cucumbers can be direct-sown outdoors in early spring like a hardy vegetable”
Cucumber seed needs about 20-21C to germinate, and the plants are frost-tender throughout. RHS puts outdoor sowing at late May or early June at the earliest, under cloches or fleece, and Teagasc independently corroborates a similar sowing window for the indoor-raised route feeding outdoor planting.
Our read Cucumbers are related to courgettes and squashes, both grown from seed in a garden bed, which makes an early direct sowing feel like the obvious approach. The germination temperature alone rules that out for most of the year in Scotland.
What to do: Sow indoors under heat for an earlier start, or wait for late May/early June with cloche protection for a direct outdoor sowing, rather than sowing early and hoping.
1 source
- RHSSow outdoor varieties directly outdoors in late May or early June
“Leaving a ripe cucumber on the plant a bit longer just makes it bigger, with no downside”
Over-ripe fruit turns yellowish, bulbous and soft rather than simply larger, and both RHS and Gardener's World say picking regularly encourages the plant to keep producing, meaning a fruit left too long actively slows the next one.
Our read With most vegetables, a bit of extra time on the plant just means a bigger harvest. Cucumbers convert that same extra time into worse fruit and a slower-cropping plant, which makes 'when in doubt, leave it' the wrong instinct here specifically.
What to do: Check plants every few days once fruit is forming and pick as soon as they're a good size, uniformly green and firm with a slightly rounded tip, rather than waiting for a certain size to make the picking trip worthwhile.
1 source
- RHSCucumbers left too long on the plant will turn yellowish, bulbous or soft. Regularly harvesting the cucumbers will encourage more to develop
“If cucumbers are grown near courgettes or squash, cross-pollination will make the cucumbers taste bitter”
Cucumbers, courgettes and squash are different species and cannot cross-pollinate with each other at all. Even cross-pollination between varieties of the same species only affects the genetics of seed saved for next year's sowing — it has no effect on the taste of the fruit forming this season, because fruit flesh develops from the mother plant's own tissue. Bitterness in cucumbers is caused by cucurbitacins, plant defence compounds that build up under stress from heat, drought, uneven watering or poor fertility.
What to do: Don't worry about which cucurbits you plant near each other for flavour reasons. If fruit turns bitter, look at watering consistency and heat stress instead, and pick affected fruit early or trim the bitter stem end before eating.
2 sources
- Iowa State University Extension and Outreach — Yard and GardenThe female flowers of each crop can be fertilized only by pollen from male flowers of the same species... Poorly flavored melons, squash, or cucumbers are typically due to unfavorable soil or weather conditions, not the result of cross-pollination... we do not see the effect of the cross in the first year.
- Purdue University Extension — Yard and GardenMost cucumber plants contain a bitter compound called cucurbitacin... Bitterness in cucumbers tends to be more prominent when plants are under stress from low moisture, high temperatures or poor nutrition.
