Asparagus is a herbaceous perennial, with both male and female plants. Asparagus plants are ferny and grow to 1.5 m. Asparagus is generally considered a temperate/cold climate plant but it is easy to grow in a subtropical climate as it thrives on the rain and has no problems with pests or diseases. Asparagus crown will continue to bear for up to 20 years, making it a worthy addition in any vegetable garden.
PLANTING AND GROWING
Asparagus can be grown by grown by seed, these plants will take 3-4 years to produce spears. Crowns are available to plant from late autumn through to early spring. Check the pH of the soil before planting this should be 6.5 to 7.0. Plant crowns 15cm-20cm deep, in beds that have been enriched with plenty of organic matter and manure. Dig trenches 20cm deep and 30cm wide, add a small mound of soil in the trench place the crown on top so the roots point down at a 45° angle. Backfill carefully with compost to a depth of about 7-10cm. As the plants grow more backfilling can be done. Space crowns 45cm apart and 1.2m between each row. Be aware that in heavily clay soils digging should be avoided as it will make the drainage worse, apply gypsum and beds should be mounded.
When the foliage browns off, cut off the old tops about 7.5 cm from the soil surface. Try to keep the berries from falling on the ground, as they will germinate and choke the bed. To maintain strong crowns it is important to apply a generous dressing of manure and seaweed during the post-harvest, pre-dormancy period. Then top with a thick layer of lucerne mulch.
Try to avoid the temptation to harvest asparagus in the first year, it is important that plants grow plenty from strong feathery foliage over the summer this will be feeding the crowns for the following year. Spears will start emerging during spring and can be harvested for a few months. It is important to check the plants daily as they can grow very fast. The optimum height is around 20-25cm, and 6-10mm in diameter. Either pull by hand or cut with a sharp knife 3-5mm below the surface. It is important to allow some spears to mature this will feed the crowns for the following year.