26 June 2015

26 June 2015

how to plant an asparagus bed

Planting asparagus

  • Asparagus beds will last for 15-20 years. Now’s a good time to get an old bed replanted or a new one established.
  • You can buy asparagus crowns in the bulb section of a garden centre, or you can grow them from seed like Rob has. They take 6-7 months to grow from seed to a size that’s big enough to plant out.
  • Rob has grown an open-pollinated variety called Mary Washington. This variety produces male and female spears. Male spears which are the long, thin ones are popular currently. You get 2 or 3 spears from a male plant whereas with female spears (the thicker ones) you usually only get one spear a day.
  • Next, Rob bare-roots each plant. The best way to do this is by washing the dirt off in a bucket of water.
  • With most of the dirt off, you simply trim the foliage back with secateurs.
  • Being a seaside plant, asparagus has to have good drainage. A raised bed provides this. If you have clay or poorly drained soil, add pumice or sand.
  • Plant into a bed that’s enriched with organic material.
  • Asparagus likes a really alkaline soil with a pH of 7-7.5. Clay soils are naturally acidic so will need a good dose of lime, whereas sandy soils are always going to be alkaline. If you’re not sure what your soil is, purchase a pH testing kit to find out. See here for how to test the pH of your soil.
  • You need about 600mm square for each plant to give it room to grow well. Rob plants 12 crowns in his bed.
  • When planting, splay the roots out on the ground, making sure you’ve got the plants the right way up. There’s no need to dig a hole.
  • Rob covers the crowns with a good quality potting mix rather than soil, because potting mix contains a good amount of pumice. He pours it over the top of the crowns and smoothes it over them.
  • Rob will ultimately cover the bed with a thick layer of seaweed and he’ll put hoops and netting over them so the birds don’t peck out the plants before they get established.
  • Shoots will appear around mid to late August. But it’s best not to pick anything in the first year; in the second year you can pick spears for about a week and in the third year you can pick for 3-4 weeks. After the fourth year you can pick asparagus spears for months on end.
  • If you have an existing asparagus bed, it’s time now to chop the old ferns back to make way for the new spears. It’s important to let the old ferns die back fully though, so that energy can go back into the ground and the crowns. If you cut the ferns back when they’re green you’re taking away energy from the plants.
  • At this time of the year you can also cover an existing asparagus bed with seaweed. Don’t wash the saltwater off. Seaweed acts as a mulch as well as feeds the plants.

Camera: Jarod Murray
Editor: Thomas Asche
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