High in vitamins, fibre, potassium, and protein, asparagus was enjoyed by the ancient Romans and Greeks and was often used for its healing properties. Today, asparagus still enjoys immense popularity. Grahame Osler from the asparagus company Denbi, tells us all about farming with this plant.
As the national sales and marketing director at Denbi, Osler is involved in many aspects of the asparagus value chain. Denbi is a family business, which has been operational since the early 90s.
“We started with asparagus farming back in 1992, originally with white asparagus and then slowly started converting to green. By 1997, we had moved over fully to green asparagus and that’s where our business began with asparagus farming,” he says.
Osler says that South Africa’s market is very small, and currently there are very few commercial asparagus farmers. It is grown primarily in Gauteng and the Free State.
“Back in the 90s, there were probably about 34 or 35 farmers in our valley. Currently, there are only two commercial farmers left. I think there are various projects around South Africa where farmers are trying to get back into asparagus farming, but it is a fairly tight circle.”
In order to sell the plant, says Osler, farmers need to produce a high quantity to justify investing in the industry.
“You’ve got to have enough volume in order to supply the market to make the investment worthwhile. But having said that, asparagus is a very popular dish. They are quite the trendy vegetable item, so you shouldn’t find it too difficult to find a market for it.”
He provides us with the following insights into growing asparagus:
A long-term investment
Osler explains that asparagus is not a short-term crop. “With asparagus farming, one of the interesting aspects, which a lot of people don’t know, is that it’s a fairly long-term investment. So, you plant the actual root system, which is called the crown, in the ground and that crown will be in the ground for approximately 12 to 15 years, and you will harvest a crop every year from that crown.”
According to a guide, by the department of agriculture, land reform and rural development (DALRRD), how deep you plant the asparagus seedlings is critical. Seedlings that are not planted deep enough will make numerous “spears” that are too small to sell commercially, and if planted too deep, will make very large spears but with a low yield.
New soil is critical
Osler says that one of the most interesting aspects of asparagus farming is that a new crop cannot be planted in the same fields as a previous asparagus crops.
“What’s interesting is you have got to plant the crowns on new virgin soil, and not old asparagus soil, because it leaves an enzyme in the ground that makes it very difficult for new asparagus to grow on old asparagus lands. So, one of the big expenses with farming asparagus, is that you have to continue looking for lands that have never been used for asparagus farming before.”
In general, Osler says that farming with the plant requires a well-drained soil. The DALRRD guide lists fertile, sandy loam or loam soils as the ideal soils for asparagus. The guide also encourages farmers to have their soils tested in the first year of planting asparagus, and then every other year after that. To prepare the soil, they recommend lime application in accordance with the test results.
The ideal climate
“The ideal climate condition is a mild summer, [which has] an average high temperature of 28 degrees. As long as your night temperature is not dropping below 15 degrees, that is sort of the temperature space that we do well in, here in the eastern Free State,” says Osler.
Asparagus is able to grow in varying weather conditions, though your yield and quality are affected by the weather. The plant produces higher yields when it matures in the 15 to 28 degree temperature window, and the asparagus ‘spears’ grow faster when it is warmer. It also needs enough moisture for good germination, especially in the first two months, as this affects the yields later on.
Too much water is not good for asparagus plants, Osler cautions. “Asparagus farming is all done out in the open. Nothing is done under tunnels. So, you’re at the mercy of the weather. If it’s a wet season, there’s not really much you can do about that. Asparagus actually doesn’t like too much rain. And if it’s a dry season, we obviously do have irrigation and we try and manage it like that.”
High cost of labour
Osler explains that another aspect of asparagus farming that may prove expensive, is labour.
“It’s very, very labour intensive. Unfortunately, there’s no mechanisation involved, and all the picking happens by hand. It’s [also] quite a tedious operation in that you’ve got effectively work six to seven days a week. You can’t leave the asparagus unpicked, so that’s quite difficult.”
Osler explains that if you put in the effort, and have a good year, farming with asparagus can be rewarding.
“Labour expenses and climbing costs make it very difficult to try and manage it, but once you do have a good year and you can manage your labour efficiently, it is great. We have seen some really great rewards by growing the market and being able to sell everything that we harvest.”
Invest in worthwhile genetics
Osler’s biggest tip for asparagus farmers is to invest in worthwhile genetics. He says that aspiring asparagus farmers should look for good genetics internationally, and make sure that they are abreast of international growth trends and techniques.
“Look at the genetics of the plant material available and look at the international growing scene as well. In all honesty, I don’t think South Africa’s moved forward progressively enough in farming asparagus compared to the rest of the world.”
Osler recommends aspiring farmers should look at the world’s bigger asparagus producers to see what they are doing. He highlights the Netherlands and the USA, specifically the University of California, as producers of superior cultivars. He also lists Peru and Mexico, Spain, the Netherlands as places where producers are developing the asparagus growing industry.
“I think a lot has changed over the years and keeping abreast of those new genetics makes a massive difference in setting up an investment in a farming operation. [This means] that your return on investment is rewarded by making sure that you’re abreast of competing with the rest of the suppliers, not only locally but internationally as well.”
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