Growing coffee: How is coffee grown?

Two years ago, Angelo planted his first coffee trees on his piece of land in Kenya. Since then, he has been intensely interested in coffee cultivation and wants to understand how coffee grows and how coffee beans are formed. This year, he plans to plant all Kenyan coffee varieties. To get his coffee seedlings, he researches online, makes phone calls, asks around on the streets, and talks to acquaintances whose parents grew coffee. Because to know where coffee beans grow, and how to go about growing coffee, you need knowledge and experience. After some research, he received a tip to try the Coffee Research Institute, which is located just 40 minutes outside Nairobi. The Coffee Research Institute is a branch department of the Kenya Agricultural and Livestock Research Organization and researches and sells various coffee varieties that grow on coffee plantations in Kenya.

Here, Angelo buys the varieties SL28, SL 34, K7, Ruiru 11, Ruiru Grafted, and Batia for 30 cents apiece.

There, along with his coffee seedlings, he also receives advice on planting the coffee plant and preparing the soil – essential knowledge for successful coffee cultivation. Why is it important to Angelo to grow a variety of Kenyan coffee trees? Kenyan coffee is considered one of the most highly traded coffees worldwide. The fine acidity, noble fruitiness, and juicy flavor make Kenyan coffee beans so popular. Anyone who understands how coffee grows and where coffee is grown quickly realizes that every region produces its very own aromas – especially in Kenya, where the coffee plantations offer ideal conditions.

Where is coffee grown?

Coffee bean cultivation stretches around the globe. Coffee cultivation worldwide is particularly widespread in countries like Brazil, Mexico, and Colombia in Latin America. Coffee is also grown in Malaysia and Vietnam in Asia, as well as in Kenya, Rwanda, and Ethiopia in Africa. Even in Australia, smaller coffee plantations now exist. The coffee shrub, meaning the coffee plant, originally comes from Ethiopia. Coffee was probably first grown in Yemen around 600 years ago. Only in Ethiopia and northern Kenya is there still originally, genetically wild-growing coffee in large areas – a fascinating insight into where coffee beans grow and how coffee is created.

In the case of Kenya, the equator runs straight through the horizontal middle of the country. Mountain ranges stretch across two geo-zones, providing moisture and precipitation – ideal conditions for coffee cultivation. Exactly here also lies a key to how coffee grows and where coffee beans are grown.

The East African state has the second most important coffee exchange after New York. Nevertheless, growing coffee in Kenya is unfortunately on the decline because land is increasingly being used for speculation and is now worth more in some regions than coffee bean cultivation – especially in the surroundings of Nairobi.

If you move off the main road, you will quickly come across large coffee plantations. Some of these lie fallow, however, as the city is expanding rapidly. Yet it is exactly this region that shows how to go about growing coffee, and offers valuable insights into the practice of coffee bean cultivation.

Angelos Land, welches er von seinem kenianischen Opa geerbt hat, ist etwa ein Acre groß (ca. 4047 Quadratmeter) und befindet sich 15 Kilometer außerhalb von Nairobi – in einer Gegend, wo Kaffee angebaut wird und die Kaffeepflanze beste Wachstumsbedingungen vorfindet.

What are the optimal conditions for growing coffee?

Coffee thrives best where there is loose, deep soil with a high humus content. Kenya's volcanic soil, with its fine acidity, offers ideal prerequisites for coffee cultivation and the successful growing of coffee beans. Exactly such conditions show how coffee grows and how coffee plants thrive to produce high-quality coffee.

Optimal conditions for coffee cultivation

1. Intensive sunlight
2. Between 15 and 30 degrees Celsius ambient temperature
3. 1500-2000 millimeters/square meter of rainfall per year

Each coffee variety has individual conditions to grow. For example, Arabica coffee varieties are highland plants that thrive best at altitudes of around 900 meters. The higher the altitude, the slower the coffee cherry grows. This makes it harder. A special quality can be recognized when the coffee cherry shimmers bluish.

Robusta coffee plants, on the other hand, are slightly less sensitive and can sprout on lower-lying cultivation areas.

The flowering period of coffee depends on precipitation, not temperature. In Kenya, there are two harvest phases due to the short and long rainy seasons.

In Germany, unroasted genus Coffea stripped of their skin and fruit are referred to as raw coffee beans.

Coffee should not grow next to other plants, as the coffee is disturbed by other root systems. It is best to plant coffee only next to coffee.

Shade plants, so-called mother plants, are also important for coffee cultivation so that the coffee bushes are not permanently exposed to the sun's rays. As an equivalent and to achieve the same effect, growing coffee is also practiced on selected slopes.

A coffee tree can grow up to 12 meters high if it were not pruned for commercial cultivation. On a coffee plantation, coffee trees often only grow up to two meters high.

How is coffee grown?

Every coffee plant has its own root structure, which is why the spacing of the seedlings for coffee cultivation varies worldwide.

For young coffee plants, a hole 60 centimeters deep is dug. A distinction is then made between the top soil, i.e. the soil laid out on top, which is 20 centimeters deep, and the sub-soil, the underlying soil, which is 40 centimeters deep.

First, a deep hole is created, deeper than the coffee seedling is set, in order to sever the roots of other plants. Otherwise, these would disrupt the nutrient uptake of the young plant.

The top soil should be a mixture that is particularly rich in nutrients and gives the young coffee plant strength to grow, so it is recommended to enhance it with a mixture of soil and fertilizer. An adequate supply of phosphorus, potassium, calcium, and magnesium, as well as nitrogen in moderate amounts, is important for the coffee plant.

The nutrient supply should guarantee a healthy pH value of 4.5 to 5.5. Daily watering of the coffee plants is a must. After planting, the soil must be conserved. This can be achieved with the appropriate cover crops. This includes, for example, growing beans for nitrogen fixation.

Which coffee varieties are most frequently grown?

Not all coffee is the same. Coffee shrubs possess a pronounced genetic diversity. Coffee belongs to the genus “Coffea”, of which there are approx. 500 genera and more than 6,000 different coffee species worldwide. However, only two coffee varieties have economic significance: Arabica and Robusta. The Kenyan coffee variations of the Arabica species are SL 28, SL 34, Ruiru11, Ruiru11 Grafted, K7, and Batia. Robusta species are not grown in Kenya.

The flowering period of a coffee tree is only a few days, and the flowers are ready for fertilization for only a short period of the day. Coffea Arabica is the only species that is a self-pollinator. Other species, including Robusta, are typical cross-pollinators and depend on the country's typical insects.

A fully grown coffee plant can produce up to 40,000 flowers in a growing season. The growing season is the period of the year when the climatic conditions allow coffee plants to grow.

This usually includes the months when the temperatures are adequate enough for the respective coffee plant genus and sufficient precipitation falls to support plant growth.

Through skillful crossing, it has been possible to bring some variations of coffee plants to the point where they bear fruits ready for harvest just one and a half years after being planted. In Kenya, these include the types Batia, Ruiru 11, and Ruiru Grafted. The coffee genera SL 28, SL 34, and K7 take two to three years before they bear fruit.

The first signs of fertility are white blossoms that bloom at the tips of the 8-15 centimeter long and 4-6 centimeter wide leaves.

Coffee fruits (drupe) are initially green and then turn yellow before they take on a bright red color and reach harvest maturity. After six to twelve weeks, the coffee cherries reach a size of 1.5 centimeters. With Arabica plants, the drupes ripen in six to eight months; with Robusta plants, in nine to eleven months.

How is coffee harvested?

In Kenya, coffee is harvested by hand. The daily yield of an experienced coffee picker is 60 to 100 kilograms of coffee. This is the net weight of the cherry. The cherries are subsequently depulped.

During this process, the coffee skin is removed, and a slippery layer remains on the bean. This bean is then either dried in the sun or, preferably, washed to remove the slippery layer. This prevents anything stuck in the layer with unwanted aromas from bleeding in. Washing maintains a uniform flavor profile.

In our climate project in Kenya, we utilize the skin of the coffee cherry by pyrolyzing it and returning it to the earth as biochar, with the goal of soil improvement. “Pyrolyzed biochar” is also known as plant charcoal.

What are the risks of coffee growing?

There are also certain risks in coffee cultivation. These include climate change, price fluctuations, or social risks. Extreme weather events like droughts, storms, or floods can cause entire harvests to fail. This then causes the global coffee price to fluctuate, which the producers suffer from. In addition, the coffee industry also faces social risks such as forced labor, poor working conditions, or exploitation of workers. For these reasons, it is recommended to pay close attention to where coffee is sourced from.

Can I grow coffee in Germany?

Yes, it is possible to grow coffee in Germany, in a domestic greenhouse or in consistently warm rooms. The coffee plant will likely not bear any fruit. However, coffee does not tolerate frost and must therefore be protected from temperatures below zero degrees. The Arabica plant in particular is a self-pollinator, and Robusta is more sensitive to cold than Arabica.

Even if the coffee plant does produce fruit, it will only do so once and so sparsely that the harvest will amount to a cup of coffee cherries at most. The climatic conditions for a coffee plant are not present in Germany, which is why it is difficult to grow coffee in Germany with a high yield. If you want to use the coffee plant not just as a crop, but see a challenge in caring for it, you can give growing coffee in Germany a try.

What should I look out for when choosing my coffee?

You should make sure that your coffee has been gently roasted and that you preferably get the coffee beans from a small roastery. Which coffee is good for you naturally also depends on your taste, but gently roasted coffees are more digestible.

For me, taste also has a time of day. Perhaps you prefer a strong coffee flavor in the morning, and waking up is your main focus. Darker roasts set the tone here. However, coffee beans must not be too oily or ashy, as all aromas might have already been lost here.

If you prefer a fruity taste, or a cup of coffee that is more reminiscent of tea, light roasts are the better choice. The coffee beans should all be the same color and not multicolored.