Posts Tagged ‘Greenhouse farming’

Knowledge a must for greenhouse farming

Wednesday, October 12th, 2011

Proper management and the right technical skills are important for successful greenhouse farming.

Greenhouses have become very popular in Kenya. These plastic constructions are increasingly difficult to ignore in our landscape. There is a very aggressive promotion for greenhouses that takes advantage of the fact that farmers are desperate to get more profit from farming, but are completely inexperienced in this technology.

The entrance cubicle provides a changing area and a footbath for the greenhouse workers

According to these companies, greenhouses are goldmines that offer the most profitable business opportunities, which no farmer can afford to miss. Reality, however, may look quite different. But without doubt, greenhouses offer a number of advantages:

• They protect vegetables against strong wind and rain

• Inside a greenhouse, temperatures are usually increased, leading to increased growth and earlier harvest compared to out-door production

• Drip irrigation saves water and makes crop production independent from rainfall

• Crops can be planted and harvested when prices are high

• With good planning, the initial investments can be recovered within 2 to 3 years.


However, these benefits do not fall from heaven. There are three major challenges:


Farmers need capital or securities to get a bank loan to start this business. For many small-scale farmers, both are not available. “Greenhouse farming is an issue of the middle class,” a Kenyan magazine wrote recently. Greenhouse owners are often people with white-collar jobs.


Makeshift and wooden greenhouses are cheaper but more prone to damage by termites and wind

Plant growth is determined by the controlled conditions inside a greenhouse. Greenhouse production requires constant temperatures and humidity control – around the clock. In large-scale professional greenhouse production, this is done with the help of technical equipment, which small farmers cannot afford. But farmers need to check temperature and humidity in small greenhouses. A greenhouse can overheat very easily in the bright sun, and condensation must be checked. Therefore, ventilation is essential and must be easy to handle and to adjust. This is especially important in hot regions, where temperatures inside a greenhouse may go up above the optimum suitable for plant growth. “You are literally tied up to a greenhouse”, a greenhouse producer from Thika said to TOF. It is very important to have reliable workers who know the requirements of greenhouse crops and can handle the challenges that occur during production.

• Disease and pest management may be the biggest challenge in greenhouse production.

The problem of pests and diseases

To recover the huge investments, high value crops such as tomatoes, peppers, eggplants or chilli are planted in greenhouses. This is a very small choice of crops, and all of them belong to the nightshade family which is susceptible to early and late blight, but also to different pests like white flies. Pathogens and insects can establish in a greenhouse environment in a very short time, and they are very difficult, if not impossible, to get rid of effectively.

To avoid this, organic farmers usually rely on crop rotation. This prevents pests and diseases associated with any crop family to accumulate in the soil. But when farmers grow the same crop in a greenhouse over and over again without rotation, diseases and pests become a big problem. Typically, after the second and third greenhouse season, the promised bumper harvests start to decline, and pests and diseases can only be controlled with increasing amounts of pesticides. This or even total crop failure may force the farmer to pull down the expensive structure.

In anticipation of these problems, some companies that produce and sell greenhouses offer advice and training to their customers.

Greenhouses & organic production

Organic greenhouse production is a major challenge, as only a limited number of pesticides can be applied. A pesticide-reduced greenhouse means that growers must practice good sanitation and pest management methods from the very start. A key element must be rotation, which means that a wide range of crops will have to be cultivated in the greenhouse.

• Suggested crops that can be planted in greenhouses besides crops from the nightshade family are: Cucumbers, courgettes, melons, broccoli, radishes, kohlrabi, okra, salads and lettuces, parsley, coriander, fennels, spinach and Swiss chard, beetroots, sugar snaps and snow peas, garden peas or garlic. Good marketing skills and abilities are required of the farmer!

• Good management includes the use of resistant varieties and biological pesticides that are allowed in organic production, such as insecticidal soaps, botanicals (neem products, tephrosia, pyrethrum etc.), and mineral-based pesticides (mainly sulphur and copper based).

• Good ventilation and air circulation, rigorous sanitation practices, and maintenance of optimum temperatures and humidity levels are essential. And before a crop is planted, it is important to thoroughly inspect the greenhouse.

Screens, doors, and walls should be checked periodically for any tear and openings sealed!

Planning and documentation

Planning is central for a profitable greenhouse production. You should not start before you have set up a complete budget using realistic calculations. If you plan to take credit, you will have to present your budget to the bank.

I would go for shade nets and drip irrigation

Su Kahumbu, a pioneer in organic farming is very well known by our readers, She is very sceptical about greenhouses, as you can read in the following text.

“I have yet to see a greenhouse under real organic production methods that is still producing organic healthy products a year on.

What are the real issues?

Do we need to make money quickly, only to end up with bank repayment schedules to buy green houses, as if this is the only solution. Or is it simply that the input providers of greenhouses have a great marketing strategy and other providers of useful inputs are asleep as I suppose?

As farmers we do not need to invest only to end up bankrupt, we should be wise and weigh our options. Our problems are too much sun, and too little water. So we need to spend our water wisely and try to keep it in the ground around the root zone for as long as we can.

Too little water …

Drip irrigation is clearly the answer. It sounds expensive when we are ignorant, yet in reality it is not as expensive as it seems. The providers of drip irrigation should make their products more readily available to the small-scale farmers. There is no real reason why I should not be able to buy any size of drip lines from an agrovet shop, the same way I buy electric cable.

… too much sun

We can mulch against too much sun, and we can use shade net. And preferably use both. Shade net is much more affordable than green housing, it does not result in any build up of pest or disease and, by nature of being cheaper, encourages and favours crop rotation.

The real choice we have to make is what to invest in first, shade net or drip kit, as the ideal farm today should have drip lines under mulch and shade netting. I would go for netting first. This allows you to keep your moisture in the soil. Drip lines alone with good mulch is also an option, however we all know that the hot sun rays on our crop leaves are causing undue stress to the overall performance of our crops. I urge all farmers today to invest in shadenet and then drip irrigation. Agrovet shops should make these input available and at an affordable price to small -scale farmers.” – Su Kahumbu.

Prices and producers

Before you buy…

Metal houses of 8 x 15 Meter cost around Ksh 180’000; they are usually sold as a complete kit including the drip irrigation system. They should last 10 to 12 years. Timber constructions are cheaper, around Ksh 100’000 for the same size. But to put up your own construction is technically more demanding, and termites, wind resistance and durability of the polythene are usually a problem. The polythene sheeting needs changing every 2 to 3 years. Compare all offers not only with respect to the price, but also concerning construction height, ventilation, plastic quality, and ask which services are included in the quotation. You should also go to see them with your own eyes before you buy.

… where to buy

Some greenhouse manufacturers in Kenya:

• Agro Tunnel International Ltd, Karen (Nairobi), Tel. 020 2012626 (office), Oliver 0722 520 083, 0733 520 083, Frida 0720 560 727 e-mail: [email protected]

• Amiran Kenya Ltd, Old Airport North Road, P.O. Box 30327, 00100 Nairobi, 0719 095 000, e-mail: [email protected]

• Horticultural Crops Development Authority (HCDA), Nairobi, Airport Road, Opp. JKIA, P.O. Box 42601-00100 Nairobi, +254-20-2088469, e-mail: [email protected]

• Shetia Industrial Chemical Ltd, P.O. Box 394, 01000 Thika, UTI complex, Kiboko Road, 0202370707; 0712770707

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