The Sunday Mail
Andrew Mangwarara
In these heat waves, what better way to cool off than with a cucumber. This fruit (although some think it is a vegetable) is 95 percent water.
Therefore when you fill a cup with sliced pieces, it is equivalent to a glass of water.
Cucumbers belong to the cucurbits plant family, which also includes the pumpkin and water melon.
They are believed to have originated from India.
Cucumis sativus is actually a creeping vine able to grow vertically on supports, even up to two metres.
We will look at growing this crop in a greenhouse.
There are many advantages of growing any crop in a greenhouse, particularly the maintenance of a pest and disease free environment.
Greenhouse production also speeds up the maturity time by providing optimal growing temperatures.
Cucumbers grown in a greenhouse mature in less than 3 months and this makes them an easy cash crop. Obviously it is important to select the correct varieties for greenhouse production.
In Zimbabwe, we have a few varieties for greenhouse cultivation. These are the trindad, temple and the olympian, although it is mostly a field variety. Other field varieties are the ashley, fletcher and marketer.
Select varieties based on their tolerance to pests and diseases, particularly powdery mildew.
Cucumbers require well drained fertile soil, preferably sandy loam rather than clay.
If however your soil does not meet the required specifications, you can opt for soilless culture by using perlite, vermiculite and saw mill waste. You can even grow your cucumbers hydroponically.
You can also grow cucumbers in 20 litre bags or containers in your greenhouse spaced 40-50 centimetres apart, with your drip providing the essential nutrients.
Organically fed cucumbers taste better since the correct balance of nutrients is easier to monitor.
Cucumbers can be directly sown into the greenhouse or one can raise seedlings in the proper seedling trays for easier transplanting.
Raising seedlings separately allows easier care of the plants but increases labour requirements when it is time for transplanting.
The optimum daytime growing temperatures for cucumbers are 24-26 degrees celsius.
Temperatures at 35 degrees celsius may be tolerable but prolonged exposure to such high temperatures will be detrimental to the quality of the fruit. Night temperatures must be maintained above 18°C as this will enhance the maturation.
Ensure that your crop receives adequate water, preferably by drip irrigation.
Keep the leaves dry to prevent fungal diseases. If you have added enough organic matter into the soil, there should be no need for supplementary feeding.
However, you can always add more organic manure or well rotted compost. Apply convectional fertilisers at a rate of 37g per square metre of compound C with additional potash as single super phosphate at a rate of 35g per square metre.
You can further top dress with Ammonium nitrate at a rate of 10g per square metre at first sign of fruit formation.
Various fertigation programmes are available for greenhouses but the basic consists of a ratio of 175:50:50 kg per hectare of NPK.
Major pests to look out for on this crop are aphids, American bollworms, red spider mites, thrips, whilst diseases such as powdery mildew, anthracnose and fusarium wilt can dampen your yields.
Cool off this summer with a cucumber.
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