Asparagus is a perennial plant which can live for several years without replanting. As the plants grow, they develop a root system called the crown. The crown consists of fleshy roots that store food and underground stems called rhizomes. As the soil temperature rises, buds on the rhizomes grow throughout the soil and become the spears. The spears develop into tall, mature plants with feathery leaves. Most asparagus plantings are not harvested until the third year, when the roots are able to store large amounts of food. Foliage is light green and fern-like. Small fruits are round and berry-like. When young, they are green, turning red when mature; then black when fully ripened. The entire fruit is planted as a seed. Asparagus is traditionally grown as a temperate crop but it is showing potential for tropical areas. The bulk of fresh asparagus production in Australia is produced in the southern states between the end of August and December. However since introduced to the subtropics it may be harvested during May, June and July. Asparagus is a fairly labour intensive crop but is well suited to small holdings with sandy soils and good watering.
In temperate environments, it is normal practice to wait three years after planting the crowns to allow accumulation of carbohydrates in the storage roots (rhizomes) before starting to cut spears. During the autumn, the above-ground ferns die off but the crown and root system survive underground and resume growth in the spring. In a tropical environment the ferns remain green and the development and growth of new buds and storage roots is a continuous process. In the tropics, asparagus plants can be expected to produce their first harvest one year after seeding and remain productive for 9 to 12 consecutive years. Following the harvest period, the practice is for the spears to be allowed to continue their natural development into ferns until the next season. It is important to apply fertilisers and adequate water during the summer months, in order to promote fern growth. The crop grows best in well aerated sandy and sandy loams but has performed well on the clay loams and clay soils. The depth of the crown affects the diameter of the spears and 150 to 200 mm is considered about optimum.