Asparagus

Asparagus is a special vegetable that is not available fresh from the region all year round. Many even call the time it is harvested the "asparagus season." In Germany this season usually begins in April and traditionally ends on June 24, St. John's Day. After that the plants should recover so they can grow vigorously again the following year. In other countries with warmer climates the season can start a little earlier or last a little longer. Outside the season you will often find asparagus as imported goods, frozen or in jars and cans. Fresh, regional asparagus usually tastes most intense because it is harvested ripe and sold quickly.

To help you place asparagus, it is useful to know the different types. There is not just one variety, but several variants that differ in color, taste and preparation. The best known are white asparagus, green asparagus and purple asparagus. In addition there is wild asparagus and special cultivated forms that are popular to varying degrees depending on country and region.

Origin and cultivation
The asparagus we eat is botanically "Asparagus officinalis." It originally comes from regions around the Mediterranean and western Asia. The ancient Romans already knew and loved it. Today asparagus is grown in many European countries, such as Germany, France, Spain, Italy and the Netherlands. Large producers also exist in North and South America and in Asia. Cultivation is laborious: asparagus grows underground from so-called shoots that sprout anew each year. For white asparagus the stalks are harvested under earth mounds so that no sunlight reaches them. Green asparagus grows above ground and acquires color through chlorophyll produced by sunlight.

Asparagus (Asparagus officinalis) is a perennial herbaceous plant of the family Asparagaceae and is among the economically most important vegetable species of the temperate climate zone. Characteristic are the shoots harvested in spring, which depending on cultivation and harvesting technique enter the market as white asparagus (bleached underground), green asparagus (photosynthetically active grown on the surface) or purple asparagus (briefly exposed to light). The deep-reaching rhizome and root system allows a planting lifespan of 8–12 years and shapes the nutrient and water economy of the crop.

Botany and morphology: Asparagus produces fine shoots (turions) that are harvested as a vegetable. After harvest the plant develops a feathery, finely divided leaf-like mass (phylloclades), which takes over assimilation for the storage organs. The species is dioecious, with separate male and female plants; male genotypes are considered to be higher-yielding and earlier. Flowers are inconspicuous and are mainly pollinated by insects. The fruits are red berries, which are inedible for humans.

Varieties and usage types: Cultivars differ in emergence dynamics, spear diameter, pigmentation, tendency to anthocyanin formation and resistance to diseases. For white asparagus, varieties with strong, straight spear thrust and low light sensitivity are preferred. Green asparagus varieties show high chlorophyll formation, slimmer spears and good head-closure stability. Modern hybrids, often male-only, increase homogeneity and yield.

Site and soil requirements: Asparagus thrives best on light to medium, well-drained, sandy to sandy-loamy soils with pH 6.0–7.5. Deep soil loosening is essential because the root system can penetrate beyond 2 meters. Waterlogging and compaction lead to root stress, increased susceptibility to rot and reduction of spear quality. Heat-storing soils,