Asparagus has a reputation for being hard to grow. It is not really that difficult, but does take some preparation and patience to obtain the best results. An asparagus bed takes a couple of years to become established, but can provide asparagus for 15-25 years after that.
Asparagus is planted using crowns, or root clumps. It is important to place the asparagus bed in a sunny place you want it to stay for the next quarter century. Till the ground well as close to twelve inches down as you can reach so the asparagus roots have soft ground to grow in. Till in about three inches of compost to add fertility and increase drainage.
Twenty crowns will feed the average family of four. Asparagus plants come in male and female versions. The males produce more spears and are more highly prized for food. The variety of asparagus varies depending on where you live, but Jersey or Improved Jersey male plants grow well almost anywhere.
To plant the crowns, first dig a furrow in your prepared ground ten inches deep and four inches wide. Spread a teaspoon of phosphorus fertilizer (0-0-46) per 20 feet of row in the furrow. Place the crowns in the furrow about 12-14 inches apart. Cover with four inches of soil/compost mix and leave the rest of the furrow uncovered for now.
As shoots grow out of the crown, gradually fill in the furrow around them. By the end of the year, the furrow should be filled in and the shoots should be above ground. Mulch three inches around the shoots to control weeds.
Asparagus will not compete with weeds, so it is very important to control them in your asparagus bed. Each year, in the spring, the shoots will come up from the crown. Cut them at ground level when they are about as big as a pencil. Do not continue to cut shoots after eight weeks. At that point, let the shoots grow so the crown has fuel for next year.
White asparagus is considered an even bigger delicacy than green asparagus is. You can grow it in the same manner as green asparagus, and from the same plants. When the shoots first appear, simply heap dirt around them, allowing only the very tip to show above ground. Continue to cover the shoots with dirt as they grow and they will blanch, or stay white. When the shoots are about twelve inches long under the dirt, cut them with a sharp knife.
Asparagus need two pounds of 10-20-10 fertilizer per 20 feet of row every January or February, right before they start bearing. After you have finished harvesting them for the year, you need to spread an additional application of 20-0-0 fertilizer. Water both applications of fertilizer in well.
Because asparagus are growing so much, they take a lot of water. You will need to water them an inch at a time every 3-5 days. The soil should be moist but not squishy.
Asparagus beds can be harvested starting two years after they are planted. In the fall, cut off the asparagus ferns and cover the bed with mulch to insulate it for the winter. Uncover them in the spring when it is time for them to grow again. If you take good care of your asparagus, you should have it for years to come.