These plants are hardy and lend themselves well for transplant, especially if the plants are overcrowded.
First, make sure there is plenty of sun - a full eight hours is ideal. Also, there needs to be plenty of room for the plants to grow; asparagus plants can continue to produce crops for typically around fifteen years, but possibly for up to fifty years.
You also want proper nutrition, so add compost to the soil to help with that. If necessary, you can also add fertilizer but make sure it is properly worked into the ground so that it doesn't burn the new plants.
Dig a trench about six to eight inches deep and ten inches wide. Your plants need 18 inches between them, so dig the trench length accordingly.
Next, you will turn to the asparagus plants in need of transplanting. You want to find the crown of the plant. This is the base of the plant where the stalks grow.
Use a garden fork to do the actual lifting of the roots. Rinse off the extra dirt. This will allow you to better see the root system for untangling.
Place the roots within the prepared trench 18 inches apart. Next, spread out the roots and keep the spears facing upward. Cover with a dirt/compost mix. The top of the crown must be two inches below the dirt.
Lastly, for proper maintenance of the new plants, keep the ground moist but not soaked. Fertilize according to the manufacturer's directions.