Victory Gardening Series: How to Grow Asparagus

By Dawn Gerlica, HF&G Horticulturist

If you purchased asparagus crowns this spring and are now wondering what to do with them, you’ve come to the right place. Asparagus requires some odd planting techniques differing from most of other garden vegetables, but if done right, you will have a crop to harvest for the next 20 to 30 years. 

Crowns or Seeds?

Asparagus is usually purchased in early spring as year-old crowns, which look very odd–like a bunch of dormant buds in the middle with white roots out to the sides about six inches. These crowns are plants grown from seed, which you can also purchase and grow, but seed should be started indoors very early in the year.  

How to Plant

When planting asparagus crowns, the ultimate goal is to get the whole crown buried under the soil six to twelve inches. Older varieties used to prefer to be about 18 inches down, but breeding has made some of the newer varieties a little more tolerant. The soil should be prepared to create a permanent bed with well-draining soil and a good amount of humus to keep plants well-fed and moist, but not soggy.  Asparagus originally grew in swamps and wet places, but not in sticky clay that becomes brick-like when it dried out. 

Within this new site, a trench should be dug to a proper depth and it should be wide enough for the roots to lie to the sides. The center of the crown should be placed on a slight mound about one to two inches high and the roots allowed to fall around. Place plants about 18 inches apart to give them enough space to grow and if planting more than one row, place each about three feet apart.  

Established asparagus spears

The most highly suggested technique to grow strong plants is to place two inches of soil over the crown and roots and wait a few weeks until the spears grow through the soil. At that point, place another two inches of soil on top and wait again for the spears to grow through, repeating the process until the trench is fully filled in. Some people don’t have the patience or time for this and fill the trench to the top from the start. Usually this will work and the spears can still push through as long as the soil is loose enough, but the first method is more advisable. Finish with a good topping of mulch to help keep the roots moist and if the weather gets dry, make sure to water. 

Harvesting

At this point, it’s a waiting game. You should not harvest from the asparagus bed the first one to two years, giving the plants time to establish. Keep the bed weeded and mulched because asparagus does not tolerate competition or root disturbance. Harvest in April and May when the spears are about six inches tall by breaking them off just above the soil surface. Some advise to only harvest the spears that are the width of a pinkie finger to not weaken the plant, but just not over-harvesting into the summer also works. Stop harvesting in early June to allow the spears to grow to their full 4 to 6-feet height and gain energy for the next year’s harvest.