Growing asparagus is not difficult - all you need is patience!

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Asparagus. Picture courtesy Julie FalkAsparagus. Picture courtesy Julie FalkYou don't need a large garden to cultivate asparagus yourself, and all you need is patience, because although asparagus is easy to grow, it takes at least a year or two from the time you plant until you can start harvesting, but as the plant gets older, more and more shoots are available for harvest over a longer period of time. Asparagus is a perennial vegetable, meaning it will come back year after year on its own, and once you have an established asparagus patch, relatively little effort is required to maintain the plants. Because asparagus plants have a 10 to 15 year life expectancy, you will save a small fortune over the years on buying expensive asparagus from the supermarket.

 This perennial rows from an underground rhizome, commonly referred to as “the crown.” It is a vigorous bushy plant with finely divided or simple leaves on long, heavily branched stems, up to 2m tall; and the numerous shoots which sprout from the crowns in spring are the part that is harvested and eaten.  

Asparagus is native to most of Europe, northern Africa and western Asia. Plants native to the western coasts of Europe; from northern Spain north to Ireland, Great Britain, and northwest Germany are treated as Asparagus officinalis subsp. Another distinct species called ‘prostrates’ is distinguished by its low-growing, often prostrate stems growing to only +-70 cm high. Wild forms of asparagus have been found growing in South Africa and are known as “katbos.”

Owing to its delicate flavour, asparagus has been used from very early times as a vegetable, and was cultivated by the ancient Egyptians, Greeks and Romans. It was included in a Roman cookbook called “Apicius” said to be the oldest surviving book of recipes, and believed to be named after Marcus Gavius Apicius, a Roman gourmet and lover of luxury, who lived sometime in the 1st century AD, during the reign of Tiberius.  The berries and underground stems were also used to cure bee stings, dropsy, heart troubles and toothache.

Today, green asparagus is probably the most common asparagus category in the United States, with spears ranging from very thin to very thick.

White asparagus is the asparagus category most preferred in Europe. The spears are deprived of light by keeping dirt mounded around the plant. Without light, the plants cannot produce chlorophyll, and therefore remain white in colour. Any variety of asparagus will produce white spears, as long as it is not exposed to light.

Purple asparagus is the category that is most commonly found in England and Italy. Purple asparagus produces thick, purple spears that are very tender and generally sweeter than varieties of green asparagus. However, the plants produce fewer spears.

Some people grow several different varieties of asparagus, because different varieties can be used to please both the eye and the palate.  In addition, the varieties will mature at different times, so if you really love asparagus, you can keep a continuous supply coming during the harvest period by planting a couple of different varieties.

In South Africa asparagus is grown commercially mainly in Tarlton to the west of Krugersdorp, Eikenhof to the south of Johannesburg, and in the Eastern Free State.

Health Benefits:

Asparagus is a very healthy vegetable, with high levels of folic acid, beta-carotene, phosphorus, potassium, calcium, iron and protein. It is also rich in vitamins A, B6, C, E and K.  It is known to help clear the skin because it flushes toxins out of the body, and its high folic acid content has been shown to prevent birth defects. It also helps to clean out the kidneys as well as the bladder, helping to prevent kidney stones, and clearing bacterial and urinary tract infections. Asparagus contains antioxidants that are known to help prevent cancer, and research suggests that adding asparagus to your diet may lower cholesterol levels. Studies also show that asparagus contains antioxidants that are known to help prevent cancer, and that eating asparagus increases the success rate of chemotherapy.

Caution:
Asparagus may bring on an attack of gout in certain individuals due to the high level of purines. Always consult your physician before starting a home treatment programme, especially for serious ailments.

In the Kitchen:

Fresh asparagus is a versatile spring vegetable that is so quick and easy to cook, and makes any meal feel just a little more special. And although it can be served in a number of ways, it's simply delicious when cooked on its own, with just a little salt and pepper. The cooked spears can also be presented with more complex sauces like beurre blanc, so search for your favourite recipes online, and surprise your family and guests with delectable, crisp and sweet asparagus.

When purchasing fresh asparagus, look for spears that are brightly coloured and have compact, tightly closed tips. Spears that are ridged or look dry have lost their flavour. Check the root ends to see how dried out they are, and if they are truly brown, reach for a different bundle.

If you are not using your asparagus immediately it can be stored in your crisper drawer, wrapped in a damp paper towel inside a plastic bag. Do not clean it first, and use within three days. You can also store asparagus upright in a container with an inch of water, and placed in the fridge, uncovered.

To prepare fresh asparagus for cooking, you need to trim up the stalks to remove and discard the tough woody ends before cooking. You can cut them off with a knife, but most cooks simply 'snap' the stalks in two. Grab the end of the spear with one hand and grasp just above the middle with the other. Then just bend until it snaps – the asparagus will naturally snap at about the point where the woody part begins. Discard the woody ends. Once you've snapped your asparagus, you can line them up and give the ends one last neat trim before cooking.

Asparagus spears range in size from thicker than your thumb to thinner than a pencil. And if your spears are on the thicker side, you might want to peel the woody stalks with a vegetable peeler after ‘snapping’ them. Some cooks also like to trim off the tiny leaves on the stems, but unless they are very spiky, you can leave them on.

If you’re concerned about your olive oil reaching its smoking point when grilling or roasting asparagus, a good alternative is avocado oil. But as long as you avoid roasting or grilling with extra-virgin olive oil, which does have a lower smoke point, there should not be a problem.

Boiled or blanched asparagus is cooked very quickly in salted water until it's fully or partially cooked. If you're not serving the asparagus immediately, plunge it into a pan of ice water to halt the cooking process. If you are using green asparagus, this will also preserve the bright green colour. Some recipes specifically call for partial blanching and icing, before finishing the cooking later. You can serve boiled asparagus however you like it. Try marinating it or giving it a light sauté in butter or olive oil and a sprinkle of salt and you’re good to go.

Steaming and then coating the spears with melted butter or hollandaise sauce is traditional. You can use an upright steam basket or a collapsible steam basket. Steaming is good for cutting calories, as it requires no fat.

Asparagus can even be cooked quickly in hot oil in a wok, before being sprinkled with soy sauce or balsamic vinegar.

Roasting asparagus in the oven is delicious because the blast of heat caramelises the natural sugars in the asparagus and deepens the flavour. Preheat your oven to 200 degrees Celsius and wash and dry your asparagus by rolling it around on a kitchen towel. Place the asparagus in large a bowl and drizzle with olive oil and a couple of pinches of salt. Toss gently with your hands until all of the asparagus is coated before spreading the spears out in a single layer on a large, rimmed sheet pan. Bake for about 15 minutes, or until golden brown and tender, opening the oven to roll the asparagus around once or twice.

To cook asparagus in a pan or skillet, coat with oil or butter and gently fry until tender.

To cook asparagus in the microwave, place the asparagus in a microwave-safe dish with 2 tablespoons of water. Cover and microwave on high for about 3 minutes. Stir, and microwave for another 2 to 3 minutes until the spears are firm but tender. Drain and cool.

Cooking asparagus on the grill is quick and easy, and adds a delicious smoky flavour to the finished dish. Wash and dry your asparagus by rolling it around on a kitchen towel. Place in large a bowl and drizzle with olive oil and a couple of pinches of salt. Toss gently with your hands until all of the asparagus is coated before spreading the spears out in a single layer in a grill basket and cook directly over the coals until tender and charred in spots. Don't walk away though, because they're ready in a flash.

Companion planting in the garden:

Plant tomatoes in rows between the asparagus, the asparagines in asparagus will protect the tomatoes from insects, whilst the solanine in tomatoes will help the asparagus plants by repelling nematodes. Petunias, nasturtiums, calendula, parsley, basil, lettuce and other salad vegetables also grow well near asparagus. However, asparagus does not enjoy growing near to onions, garlic, potatoes and other root vegetables.

Field of asparagusField of asparagusCultivation & Harvesting:

Several high quality strains of asparagus crowns and seeds are available from top local nurseries and mail order specialists online. If possible, purchase one or two year old crowns so that you can start harvesting earlier. This perennial plant may take takes four years before it reaches its full bearing potential, and its roots can penetrate 3m or deeper, but it will keep on producing spears for 15 years or more.

It's best to grow asparagus in the ground, but it can be grown in very large pots or 60l patio bags for a limited time.

Both asparagus seeds and crowns can be planted in late winter, or in early spring when the frosts have finished. In the following harvesting season after planting out established crowns you can harvest a small crop, but if you are growing from seed you will only be able to start harvesting in the spring of the third year. Mature plants can be cut as the spears appear for about 10 weeks in spring and early summer.

In South Africa asparagus can be planted in a fairly wide climatic range, but produces the best quality crops where there is a cold or frosty season to induce dormancy in winter. However, although it is a hardy plant, the young spring shoots can be damaged by frost or freezing temperatures, causing the damaged stalks to go black before dying off. If a hard frost is expected, cover the stalks to protect the spears. If frost does damage the stalks, cut them off at ground level and the plant will recover and produce new shoot to harvest.

Better quality spears and higher yields occur when asparagus matures during periods when the spring and early summer temperatures are about 16° to 25°C. Higher temperatures result in more fibre in the spears, making them less appetizing; and temperatures below 12°C result in slower growth and therefore lower yields. Cut the spears with a sharp knife 15cm below soil level as soon the tips emerge through the heap. Green asparagus is cut when the spears are about 15cm long. For white asparagus, heap soil over the rows to about 30cm in spring.

Asparagus is easy to cultivate in the home vegetable garden, and can be grown in full sun to partial afternoon shade. It is sensitive to high soil acidity and grows well in soil with a pH of 6 to 6.7. If your soil is too acid, with a pH lower than 5.5, adjust the pH by adding lime one month before planting or adding any other fertilisers. Dolomitic lime is recommended in cases of magnesium deficiencies. Asparagus is fairly tolerant of high salt content and alkaline conditions and thrives in sandy very well drained soil to which lots of compost and mature manure has been added, plus a complete fertiliser like 2:3:2.

Because asparagus lives so long it is essential to prepare the soil well before planting by digging the beds over thoroughly to a spades depth, and preparing trenches about 30cm wide and 20cm deep. If you wish to ridge the soil up high against the stems in spring, allow at least 1m between the rows.  Set the crowns down about 50cm apart at the bottom of the trench, spreading the thick roots horizontally around each crown. Cover the crowns with about 5cm of soil and gradually fill the trench with soil as the plants grow.

One week after harvesting begins in spring, nitrogen should be applied on moist soil in the form of LAN, repeat this again 6 or 8 weeks after harvesting. For established crops an application of 2:3:4 fertiliser is recommended annually in summer. Phosphates like ‘super phosphate’ are important for root growth, but are only used when planting out. Strangely, organic fertilisers are not recommended by farmers to fertilise asparagus fields.

Planting depth is critical in asparagus production because if planted too shallow the spears will be very large, and if planted too deep, the spears will not produce as much. The crowns are initially covered with only 5cm of soil and later to the depth of 10cm. The seed should be sown in fairly deep furrows and the furrows should be filled up to allow the crowns to be 10cm beneath the soil surface.

It is important to keep the beds free of weeds which compete with the plants for water and nutrients, and which often harbour unwanted insects and diseases.

Water regularly, especially during the first two months after planting the crowns, and thereafter, in the absence of rain, irrigate well every two weeks. It is important to irrigate during harvesting time, and if there is no rainfall, irrigate deeply every 3 to 4 weeks. Because the roots of established asparagus plants go down deep into the soil, once established, irrigation is only needed in summer during extreme drought conditions.

Asparagus spears are harvested by cutting off the stalks with a curved knife about 3 inches below the soil surface when they are immature and still tender and crisp, and once they have grown about 15 to 20cm above the ground, and are between 1 and 2cm in diameter. Mature plants can be harvested for 6 to 10 weeks each spring.

After harvesting is finished, leave the plants to grow their fern like leaves which will feed the crowns through summer and ensure a good crop next season.

Asparagus plants are unusual because they're dioecious, which means some plants are male while others are female. And because male plants are better producers of asparagus spears, you may consider replacing your female plants with males. Although this isn't necessary, if space is limited, there are several reasons why male plants are generally preferable to female plants. Because male plants don't use stored nutrients to make fruit, they generally have more energy available to make new spears than female plants, up to three times as many. Male plants tend to start producing spears earlier in spring than female plants, and also live longer.

To remove females, as summer progresses, watch out for the appearance of red fruits on some ferns, indicating a female plant, and place a wooden or plastic marker well into the soil at that plant's base. Don't use ties on stems as markers, because these may be lost when the plant dies back in winter. Early the next spring, dig up the marked female crowns, taking care to remove all the roots, without disturbing the roots of other plants, and replace the females with male plants.

Leave the ferns to die down naturally in autumn, then trim off the dead stalks to ground level, level the ridges so they can be rebuilt next spring when the crowns start growing again, and pile on plenty of mature manure or compost. This will protect the roots from the cold and give them plenty of food to produce new stems in spring.

Propagation:

A few varieties can be grown from seed collected from the small red berries produced in autumn. Asparagus seed is highly viable and germinates easily under the right conditions. In order to speed up the process of germination soak the seeds in water for 24 hours before planting. Germinate the seeds first in a seedling tray in a warm and protected area like a hothouse or a cold-frame, or sow in open ground during spring, after the last frosts. Keep the seedlings moist and be patient as they may take some time to shoot. Once the seedlings are large enough transplant them into individual pots and grow them on until they are about 15 to 18 months old, with a well-formed crown.

Pests & Diseases:

Garden grown asparagus is seldom attacked by pests, but look out for asparagus beetles & flies, cutworms and aphids, as well as Fusarium wilt and asparagus rust.

If you notice cutworms in the soil when digging the beds apply cutworm bait before planting or sowing. Cutworms cause damage by eating off the part of the spear underground. As a result, the damaged spear develops with a crooked tip.

Asparagus beetle (Crioceris aspargi) Harvesting new shoots just below the surface of the soil often helps to control problems with asparagus beetles, which often lay their eggs on tender shoots near the soil line. Both the adults and larvae attack spears and ferns. The beetle damages the tips of the spears as soon as they emerge from the ground by eating them. The larvae also secrete a dark fluid, which stains the plants. Commercial and organic sprays for beetles are available, but remember that this will delay harvesting due to the poisons withholding period.

Asparagus fly (Zacherata asparagi) eggs are laid in the shoots of the plant and the larvae tunnel into the shoots and weaken them. Attacked spears become crooked and when they emerge above the ground the growing tip resembles the handle of a walking stick. Heavy infestations may reduce yield. This can be controlled with registered chemicals.

Fusarium wilt symptoms are poor growth and yellowing of the plant followed by withering and drying up of a few branches accompanied by brown discolouration of the parts near the base. It spreads to all the branches and the entire plant withers and dies. To avoid this, avoid planting in poorly drained soil which stays wet for a long time, keep soil should loose and well aerated, and avoid injury to the crown during harvesting. New crops should not be planted in or cultivated near old infested soil previously planted with asparagus.

Asparagus rust infected plants are characterised by the occurrence of dark-red pustules on the ferns. This can be controlled with registered chemicals.

Caution:

The information contained within this website is for educational purposes only, documenting the traditional uses of specific plants as recorded through history. Always seek advice from a medical practitioner before starting a home treatment programme.

Toxicity:  Only the young shoots of asparagus are edible, the berries are poisonous.