Garden asparagus (Asparagus officinalis) is a flowering plant species that undergoes photosynthesis in its stems and branch leaves. Garden asparagus has a long history of cultivation for culinary and agricultural purposes. The ancient Greeks first cultivated this plant 2,500 years ago.
I. Appearance and Characteristics
Asparagus (Asparagus officinalis) is a perennial flowering plant species in the genus Asparagus native to Eurasia. Widely cultivated as a vegetable crop, its young shoots are used as a spring vegetable.
The English word asparagus derives from classical Latin but the plant was once known in English as sperage, from the Medieval Latin sparagus. This term itself derives from the Greek aspharagos or asparagos, but the Greek terms are of uncertain provenance: the latter form admits the possibility of a Proto-Indo-European root meaning “to jerk, scatter,” directly or via a Persian descendant meaning “twig, branch”; but the Ancient Greek word itself, meaning “gully, chasm,” seems to be of Pre-Greek origin instead.
In English, A. officinalis is widely known simply as “asparagus”, or sometimes “garden asparagus”.
Asparagus was corrupted in some places to “sparrow grass”; indeed, John Walker wrote in 1791 that “Sparrowgrass is so general that asparagus has an air of stiffness and pedantry”. The name ‘sparrow grass’ was still in common use in rural East Anglia, England well into the twentieth century.
In Turkish, asparagus is known as kuşkonmaz, literally “[a] bird won’t land [on it]”, in reference to the shape of the plant.
Asparagus is an herbaceous, perennial plant growing to 100–150 centimeters (3–5 feet) tall, with stout stems with much-branched, feathery foliage. The ‘leaves’ are, in fact, needle-like cladodes (modified stems) in the axils of scale leaves; they are 6–32 millimeters (1⁄4–1+1⁄4 inches) long and 1 mm (1⁄32 in) broad, and clustered in fours, up to 15, together, in a rose-like shape. The root system, often referred to as a ‘crown’, is adventitious; the root type is fasciculated. The flowers are bell-shaped, greenish-white to yellowish, 4.5–6.5 mm (3⁄16–1⁄4 in) long, with six sepals partially fused together at the base; they are produced singly or in clusters of two or three in the junctions of the branchlets. It is usually dioecious, with male and female flowers on separate plants, but sometimes hermaphrodite flowers are found. The fruit is a small red berry 6–10 mm (1⁄4–13⁄32 in) in diameter, which is toxic to humans.
Plants native to the western coasts of Europe (from northern Spain to northwest Germany, north Ireland, and Great Britain) are treated as A. officinalis subsp. prostratus (Dumort.) Corb., distinguished by its low-growing, often prostrate stems growing to only 30–70 cm (12–28 in) high, and shorter cladodes 2–18 mm (3⁄32–23⁄32 in) long. Some authors treat it as a distinct species, A. prostratus Dumort.
II. How to Grow and Care
Sunlight
Asparagus plants grow best in full sun. Without enough daily sunlight, you will wind up with thin spears and weak plants that are prone to problems.
Temperature and Humidity
During the growing season, asparagus prefers a temperature of 70 to 85 degrees Fahrenheit during the day and 60 to 70 degrees at night. In the spring, it will begin to grow shoots when the soil temperature reaches 40 degrees. Any frost after the shoots start growing will cause damage. You may see slow growth with temperatures above 85 or below 55 degrees.
Watering
Asparagus needs regular watering, especially while young; give it 1 to 2 inches of water per week during its first two growing seasons; give older plants about 1 inch per week. Give them a good start when you first plant them and you’ll have fewer problems in future years. Consider adding drip irrigation or a soaker hose to the asparagus bed.
Soil
For a long-lived perennial like asparagus, it pays to take the time to improve your soil. Work in plenty of organic matter and make sure the soil pH is in the neutral 6.5 to 7.0 range. Also, get rid of any weeds and large stones in the area. The soil must drain well so the plants are never sitting in water.
Fertilizing
When preparing your asparagus bed, add compost and an all-purpose organic fertilizer to the trench, as well as rock phosphate, a natural mineral powder that promotes root growth. These nutrients will help your asparagus develop a good, strong root system. To keep the soil rich and help feed the asparagus plants, top dress the soil annually with compost. You can do this in early spring before the shoots appear, or in the fall after the fronds have died back and been cut to the ground. Asparagus is a heavy feeder, and you should also give it a dose of fertilizer in mid spring when it is actively growing, following product label instructions.
Pruning
Towards the end of the season, asparagus foliage will begin to turn yellow, which can be cut back to ground level. During the growing season, it’s important to reduce the competition from weeds. Regular weeding is required to ensure that the plants receive the maximum amounts of available nutrients in surrounding soils. Weeding with a tool or machine can easily damage asparagus roots; it is therefore best performed manually.
Propagation
Garden asparagus propagates best through division, preferably in Spring or Autumn. It is an easy-to-propagate plant, and successful propagation can be recognized by new growth. Ensure adequate space and care for optimal results.
Repotting
Repot garden asparagus in early spring every 2-3 years as it resumes growth, to accommodate its tall, bush-like stature. Choose a deep pot to allow for its long roots. Post-repotting, provide full sun and avoid overwatering for best recovery. Consistent care ensures garden asparagus’s vigor and yield of tender shoots.
Overwintering
Asparagus plants need to be cut to the ground each year before the new growth starts. The timing is up to you. You can remove the stalks in the fall or winter after the leaves have turned yellow and died back naturally. The advantage of early removal is that it prevents pests, such as asparagus beetles, from overwintering in the stalks. Leaving the stalks standing through the winter, on the other hand, has the advantage that the plant debris can hold snow, which protects the asparagus crowns in freezing temperatures. In any event, the dead stalks must be removed in the spring before the new growth starts.
Pests and Diseases
Asparagus does not have too many problems in the garden. Fusarium wilt can be a problem with older varieties, but you can avoid it by planting resistant hybrid varieties. The biggest pest is the asparagus beetle. Keep watch for them as the spears emerge in spring. They’re most active in the afternoon. Handpick the Beatles and drop them in a bucket of soapy water when there are only a few. Otherwise, diluted neem oil should keep them under control.
III. Uses and Benefits
- Ornamental uses
Garden asparagus isn’t the most commonly grown vegetable, as it can be difficult to grow in many places. However, it does have a unique bushy attraction other plants don’t have. As it can grow in areas other plants usually cannot, garden asparagus is perfect to grow in otherwise unused areas. It pairs especially well with tomato, comfrey, coriander, and dill in vegetable gardens.
- Culinary uses
Only young asparagus shoots are commonly eaten: once the buds start to open (“ferning out”), the shoots quickly turn woody. The roots contain starch.
The shoots are prepared and served in a number of ways around the world, typically as an appetizer or vegetable side dish. In Asian-style cooking, asparagus is often stir-fried. Cantonese restaurants in the United States often serve asparagus stir-fried with chicken, shrimp, or beef. It may also be quickly grilled over charcoal or hardwood embers, and is also used as an ingredient in some stews and soups. In recent years, asparagus eaten raw as a component of a salad has regained popularity, although it may cause digestive issues for some.
Asparagus can also be pickled and stored for several years. Some brands label shoots prepared in this way as “marinated”.
Stem thickness indicates the age of the plant (and not the age of the stalk), with the thicker stems coming from older plants. Older, thicker stalks can be woody, although peeling the skin at the base removes the tough layer. Peeled asparagus will poach much faster. The bottom portion of asparagus often contains sand and soil, so thorough cleaning is generally advised before cooking. Plants bearing seeds produce spears that are smaller and thinner, and plants without seeds produce larger and thicker spears. Thickness and thinness are not an indication of tenderness or toughness. The stalks are thick or thin from the moment they sprout from the ground.
Green asparagus is eaten worldwide, and the availability of imports throughout the year has made it less of a delicacy than it once was. In Europe, according to one source, the “asparagus season is a highlight of the foodie calendar”; in the UK this traditionally begins on 23 April and ends on Midsummer Day. As in continental Europe, due to the short growing season and demand for local produce, asparagus commands a premium price.
IV. Harvesting and Storage
In most cases, harvesting your asparagus spears won’t begin until the third year after they are planted. Here’s a timeline of what to expect:
- First year: The plants need this time to become established and build up their root systems, especially in the first year of planting when the shoots aren’t large.
- Second year: Some gardeners harvest spears if they are the thickness of a pencil or more during the second year. For healthy, well-established asparagus plants, patience is key.
- Third year: By the third year, you should be able to harvest for about two weeks. Then let the new spears grow undisturbed after that initial harvest. Fronds will unfurl from the spears, creating the pretty, airy foliage that feeds the plant.
- Fourth year: In the fourth year, begin harvesting spears that are 5 to 7 inches long before the tip becomes loose (diameter doesn’t matter). You can either snap off the spears or cut them with a knife, just above the soil line. If you use a knife, be careful you don’t also slice the later shoots that are still underground and haven’t yet poked through.
- Fifth year and beyond: Harvest for about four to six weeks in the fifth year. In subsequent years, the shoots will continue emerging from the soil throughout the spring. After you’ve been harvesting for more than a month and the weather starts to warm, the shoots will begin to get spindly. At this point, allow the plants to grow into their mature ferny foliage, which will feed the roots for next year’s crop. Asparagus plants can continue producing for 20 to 30 years and can be divided or transplanted if they become overcrowded or could benefit from a move.
