Crop Guide: Nutritional recommendations for Cucumber - Haifa-Group

with a continental climate, the need to ventilate the greenhouse actively throughout the hot
summer renders the practice less economical. Apply carbon dioxide during the day or any part of
the night when artificial light is supplied. It is economically feasible and highly advisable to use
liquid carbon dioxide (carbon dioxide gas liquefied under pressure) because of its guaranteed
purity and amenity to accurate concentration control. Liquid carbon dioxide is also preferred
because burning natural gas or propane to generate carbon dioxide increases the risk of plant
injury from gaseous pollutants, e.g. ethylene.
2.2.5 Seed germination
Seeds germinate and emerge in three days under
optimum conditions. During this time seed coat
remains tight.
Once cotyledons emerge, roots develop quickly.
Sunlight delivers photosynthates to true leaves and
root system.
During the 1 st week cotyledons integrity is very
important, and if damaged, plants will set back.
Seedlings may recover but they will be weak and
susceptible to stresses.
For proper germination, soil temperature must be
above 15°C (60°F). If the soil is too cold and wet
poor seedling emergence will take place.
2.2.6 Planting
Cucumbers growth season is relatively short, lasting 55-60 days for field-grown varieties, and over
70 days for greenhouse varieties.
Planting dates
Cucumbers are almost always direct seeded. Like most cucurbits, they do not transplant well and
transplant costs would be hard to recover. Planting depth is 2.5-4 cm (1-1.5 inches). Too deep
delays emergence.
Pickling cucumbers have to be very precise on planting dates so that harvest will coincide with
processor needs.
For early crop, container-grown transplants are planted when daily mean soil temperatures have
reached 15°C (60°F) but most cucumbers are direct seeded. Early plantings should be protected
from winds with hot caps or row covers. Growing on plastic mulch can also enhance earliness.
Spacing
Planting spacing depend on the growth method, variety and harvesting method.
Close spacing increases yields, provides more uniform maturity and reduces weed problems. It also
results in shorter fruit with a lighter color.
On the other hand, high plant population requires more seeds and slightly higher fertilizer rates.
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Figure 2.1: Cucumber seedling's cotyledons; first
true leaves are emerging between the cotyledons.