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Grow your own olives

January 17, 2016

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Huge green olives
Huge green olives

Having a few olive trees in your garden is rapidly becoming the ‘in thing’ to do, but, unfortunately, few people are doing their homework before rushing off to invest in saplings. This week, therefore, let’s take a sensible look at this subject.

There is no getting away from the fact that productive olive trees are a beauty to behold: that correctly cared for olive trees can — and do — live and fruit for generations, adds to the lure and this, combined with dreams of heaps of luscious olives to eat, along with litres of virgin olive oil for home use, has added to the current furore.

It is perfectly true to say that olives can be, and are, cultivated in Pakistan — but please remember that our wonderful country is huge and that climatic and soil conditions vary tremendously throughout. Countless plant species which thrive in the north, do not take kindly to being grown in for example Karachi; and olives, being quite a fussy species, are one. This is not to say that an olive tree will not grow in Karachi — it may — but, as a direct result of high humidity / monsoon rains / soil conditions plus lack of consistently low temperatures for an acceptable period over the winter months, any trees which survive will be prone to an incredible amount of insect attacks and fungal diseases. Additionally, if they do manage to bear any fruit — this is highly unlikely — the fruit will be of poor quality and in extremely low numbers.

Olives are at their best in what is known as a ‘Mediterranean climate’: this means regions in which summers are both hot and dry, winters are relatively cool, frost is rare and there is an annual average rainfall of 600 - 800 mm, sporadically in late autumn, winter and early spring. Regions with a basically Mediterranean climate but experiencing less than suitable rainfall, can, if soil conditions suit, still be used for olive cultivation as long as adequate irrigation is provided. This species is very susceptible to temperatures: frost causes serious damage, especially to young trees and blossom and established trees can die if winter temperatures drop to minus 5 - 7oC. Branches are brittle and a snowfall of any significance wreaks havoc.

Perfect winter nighttime temperatures for olives, should hover between 2 – 7oC for at least eight to 10 weeks as the trees need this ‘chill period’ if they are to develop blossom in early spring: no chill period means no blossom, therefore no fruit.

To complicate matters further, fruit set and early development depends on temperatures too: maximum day temperatures should not be higher than 25oC during May and June if olive trees are to crop to their full potential.

Ripe black olives
Ripe black olives

The above guidelines immediately rule out the suitability of olives for huge swathes of the country.

Then there is soil: olives must have well-drained soil. They do not tolerate water-logging as this causes them to develop root diseases. Neither do they like clay soil. Sandy soil is fine, if intensive irrigation and feeding is maintained.

The perfect olive-growing soil is stony, has a high content of gravel and a soil ph of 5.5 - 6.5.

Areas of the country which have been identified — by government and private organisations — as being suitable for olive cultivation, include: the Potohar Valley where an ambitious government scheme intends, over the next five years, to create ‘Olive Valley’ on 50,000 acres of land; Lahore and surrounding areas, Multan, Bhawalpur, Layyah, Sahiwal, Faisalabad, Jang, Gujerat, Rawalpindi, Islamabad, Simli and Chakwal in Punjab.

The valleys of Azad Kashmir, Malakand, Swat, Dir, Chitral, Landi Khotal, Dara Adam Khel and Pak/Afghan border region valleys in Khyber Pakhtunkhwa, plus, North and South Waziristan and Pak/Afghan border valley regions of Balochistan. Olive planting campaigns — and the grafting of cultivated olive varieties onto indigenous wild olive stock — is currently under way in many of these areas; following Turkish, Italian and Spanish advice olive varieties like ‘Frantoio’, ‘Coratina’, ‘Gamlik’, ‘Arbequina’, ‘Koroneiki’, ‘Ottobracia’, ‘Noci’ and ‘Uslu’ are favoured for cultivation.

Olive trees begin their productive life at three to five years of age in general and, as previously mentioned, can continue fruiting for literally hundreds of years.

Ancient olive trees
Ancient olive trees

One mature tree — irrespective of whether the variety is for olive oil or for eating purposes — can produce 15 to 25kg fruit per year: it takes, on average, 10kg of top quality olives to produce one litre olive oil.

The trees must be pruned each year — preferably during December and January.

Pruning is an art: olives bear fruit on the previous year’s new growth but bear little, if any, fruit on new growth which is growing straight up in the top of the tree — this upward growing new growth is pruned back to 15 to 25cm if it is a main stem and four to six inches if a supplementary stem. The majority of the crop forms on down facing / trailing growth and this is not pruned unless it is exceptionally long / straggly. Otherwise, all sucker growth is cut away from the base of the tree and from off the tree itself, including from the point where branches join the trunk. This ‘centre’ of the tree is kept clear to assist air circulation and to help prevent fungal problems from occurring, should unseasonal rain arrive. A badly pruned olive tree may not fruit for one to three years — an unpruned olive tree will, at some point, stop fruiting.

Being personally sceptical about climatic suitability / adverse effect of summer monsoon in some — not all — regions, I advise serious thought before rushing out to purchase olive saplings for your garden although the decision, of course, is yours!

Please continue sending your gardening queries to zahrahnasir@hotmail.com. Remember to include your location. The writer does not respond directly by email. Emails with attachments will not be opened.

Published in Dawn, Sunday Magazine, January 17th, 2016